# Gaggia Dimmer Switch - low pressure pour



## MrShades

I've done some more "fiddling" with my dimmer switch modded Gaggia Classic - and it seems (certainly to me) as if the Ulka (48W) pump doesn't work as well with the dimmer as the Invensys pump (65W).

Put it this way... I had an Ulka pump in the machine, and swapped to an Invensys last night... and I won't be putting the Ulka back.

The Ulka stopped and started when the heating elements cut in / out, and didn't work well at low voltages (low dimmer settings). The Invensys appears to be much better in both of these regards, running at low settings and only fluctuating slightly when the heating elements cut in (at low settings; it makes no difference at all when at high dimmer settings). You can hear the pump fluctuations on the video:

Anyway, the "low pressure" pour is shown here.... It came after Bootsy suggested that he was getting good results from a long, slow, low-pressure pour on the Vesuvius - so I thought I'd try (as best as possible with a dimmer modded Classic) to replicate it (£300 vs £3000).

Have a look:






Both were very tasty... but the low-pressure one was very good indeed!

I'll post pics of the resulting shot in the cup later - but they're still on my phone.

So - anyone contemplating the dimmer mod really should think about changing the Ulka pump for an Invensys one if you don't get the level of control that you're seeking (it's still not perfect, but definitely better!).

Shades


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## majnu

Ooooh I'll watch the videos later but did you use this with your 40/300W slide dimmer? What reading (bar) were you getting from the lowest setting?


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## MrShades

Yes, with my slide dimmer. Difficult to say what the lowest pressure is - as I can't easily do dynamic pressure (other than with my modded portafilter gauge with needle valve), but better than with the Ulka.

The slide dimmer will stop it completely, and run at "flat out", and do most things in between - but quite how low it'll go when actively pumping I'm not sure. I'd guess at 1 or 2 bar.

I really need to run a dynamic pressure test, with a gauge like yours, which could be in the offing ;-)

Have a look at the videos and compare the 'full speed' with 'low pressure' and see what you think...


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## Bigpikle

Damn I need a good coffee after watching those!

How hard is swapping the pump


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## MrShades

5 minutes with a screwdriver and a pair of pliers.... at most. Couldn't really be much easier.

(Hint - the easy way to do it is to remove the output pipe from the top of the pump [pliers] then remove two screws in the pump mounting plate (either side of the base of the pump), then pull the two wires off the pump - and finally lift the entire thing, with rubber mount, out of the machine - complete with feed pipe. You can then fit a new/different pump into the rubber mount/clip and afix the feed pipe quite easily - before lowering it back into the machine, screwing the two screws into the mounting plate and finally attaching the output pipe - tightening with pliers).... 5 mins.


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## majnu

MrShades said:


> Yes, with my slide dimmer. Difficult to say what the lowest pressure is - as I can't easily do dynamic pressure (other than with my modded portafilter gauge with needle valve), but better than with the Ulka.
> 
> The slide dimmer will stop it completely, and run at "flat out", and do most things in between - but quite how low it'll go when actively pumping I'm not sure. I'd guess at 1 or 2 bar.
> 
> I really need to run a dynamic pressure test, with a gauge like yours, which could be in the offing ;-)
> 
> Have a look at the videos and compare the 'full speed' with 'low pressure' and see what you think...


Around 20 seconds for first drops to show and then 35 seconds later you stopped the shot. How many grams was in the cup? and how much did you dose? It reminded me of when I choke the machine from a really fine grind and it takes a long time for full extraction. However, it's all in the taste so:

How would you compare the taste of both shots? Does the low pressure one have a more syrupy consistency, does it give better mouth feel, is it more sweet, does it enhance any of the notes in your blend? Is it more balanced? The Low pressure shot does look darker to me, but then it depends on the output on both shots.

I hope my dimmer comes tomorrow and more importantly I hope it works.









Edit - I can see a huge difference in both pucks though. The low pressure one looks dry like what I saw in a Youtube video, Joe experimenting with a Slayer, or some video like that.


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## MrShades

I didn't weigh the in/out on those pours - it was probably something like 17.5g in and 35g out.

I ran another at VERY low pressure and I thought the pump was doing pretty much nothing other than making a noise... as it took around 1min for any drops to appear! Didn't taste too great either...

Back to the shot I poured yesterday: It was sweeter than usual, with more distinct taste notes, but the mouthfeel wasnt as good as a 9bar shot. Tasted great though.

The very low pressure pour I've done today tasted worse, and the mouthfeel was MUCH worse again... not much crema and not gloopy.

But to try and be more quantifiable, I've got the pressure gauge with adjustable needle valve on the Classic now, and run a bit of water through it.

It'll run at VERY low pressure quite easily.... like 2 bar or less. It's pretty stable at that, as you can see on the video. I can then ramp up to 5-6 bar, and again it's pretty stable...

When 'flat out' it's pumping around 9 or 10 bar, and the OPV is obviously cutting in at this point (which I should perhaps turn down a bit!) and the pressure is a little more erratic, but no big deal.

Anyway, see what you think:


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## Bigpikle

that looks very interesting if you can pre-infuse at 1-2 bar and then choose a pressure for the main shot as well. I;m wondering if the installation of the dimmer is beyond my electrical skills though. I know there are a few threads on it in here so may brave it after Xmas when I have some time. But then, I should also perhaps be using my Pavoni for this stuff!


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## majnu

Bigpikle said:


> that looks very interesting if you can pre-infuse at 1-2 bar and then choose a pressure for the main shot as well. I;m wondering if the installation of the dimmer is beyond my electrical skills though. I know there are a few threads on it in here so may brave it after Xmas when I have some time. But then, I should also perhaps be using my Pavoni for this stuff!


It's easier than the OPV mod and takes only a couple of mins to do.


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## MrShades

...but if you need to buy a new pump as well as a good dimmer then it could cost >£40 to achieve...


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## Bigpikle

I hadnt realised it was that easy - done the OPV mod in a few mins easily enough. £40 is a fair bit I guess - will look out to see what the results turn out to be. Does pre-infusion really make a difference in the cup with a Classic?


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## MrShades

It typically helps with any machine - and with the dimmer you can preinfuse without deactivating the solenoid and drawing water off the puck


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## mobile

I suspect the reason why the dimmer works better with the Invensys pump is due to the higher wattage of that pump Vs. the Ulka one. Dimmers have a range for which they will operate and it could be the Ulka pump is below that range.


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## MrShades

Lots of people have tried lots of different dimmers (including ones with v low minimum loads) and they all give similar poor results with ULKA pumps. I think it's more down to the apparent fact that the ULKA pump just stalls when faced with low (chopped) voltages. The Invensys pump seems to handle the low (dimmed/chopped) voltages much better and behaves in a more linear fashion.

Whilst they both do the same job to a similar degree within a standard machine, the difference in quality/usability of the pumps tends to be more material in a dimmed machine.


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## mobile

I've fitted a motor speed controller to my Gaggia Classic. It controls from the lowest setting (5W), without the pump stalling. It has an off-switch position, enabling me to press the brew switch, opening the solenoid, without the pump starting. This allows water to drop out of the shower head, thus giving a pre-infusion. After some time of pre-infusion I then switch the dimmer on at minimum setting and slowly wind it up when I start getting a pour.


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## MrShades

mobile said:


> I've fitted a motor speed controller to my Gaggia Classic. It controls from the lowest setting (5W), without the pump stalling. It has an off-switch position, enabling me to press the brew switch, opening the solenoid, without the pump starting. This allows water to drop out of the shower head, thus giving a pre-infusion. After some time of pre-infusion I then switch the dimmer on at minimum setting and slowly wind it up when I start getting a pour.


Have you got a link or more info on the actual controller - as it would certainly help others.

Sounds good though - well done!


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## Hugh

I just got this;

http://www.ebay.co.uk/itm/390920670618?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT ("Practical Rotating Triac LED Dimmer Switch Wall Socket for Light Lamp 300W 220V") It controls flow very well indeed but it can only reduce pressure by 1.5 bar. I pull the shot with the dimmer set at the lowest flow before stalling and use a fine grind - certainly improves the quality of medium roast coffee. (It also seems much more robust than the Varilight H_10 Fan Controller i was using which was getting a bit hot and bothered.)

I tried this,

http://www.ebay.co.uk/itm/272118039260?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT which is a motor speed controller but the avensis pump didn't like it.


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## mcrmfc

@MrShades cry for help! Finally got round to trying this today. I have the Invensys pump and a 40-300w slide dimmer wired in.

The good news is it seems at 0 to stop the pump entirely and at max I get the full 10 bar on my panel mount.

The bad news...inbetween this the solenoid keeps getting triggered. So with my very numpty electronics knowledge I am assuming the circuit is getting broken causing the solenoid to kick in.

Off the top of anybody's head if they can give me any pointers that would be awesome.

To complicate things I also have an ssr in that circuit for my gravimetric stuff. I had a similar issue to this with a dodgy ssr but once i got a decent one it has not missed a beat.

Cheers in advance!


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## MrShades

mcrmfc said:


> @MrShades cry for help! Finally got round to trying this today. I have the Invensys pump and a 40-300w slide dimmer wired in.
> 
> The good news is it seems at 0 to stop the pump entirely and at max I get the full 10 bar on my panel mount.
> 
> The bad news...inbetween this the solenoid keeps getting triggered. So with my very numpty electronics knowledge I am assuming the circuit is getting broken causing the solenoid to kick in.
> 
> Off the top of anybody's head if they can give me any pointers that would be awesome.
> 
> To complicate things I also have an ssr in that circuit for my gravimetric stuff. I had a similar issue to this with a dodgy ssr but once i got a decent one it has not missed a beat.
> 
> Cheers in advance!


How or where have you wired the dimmer in?

You should be removing one of the wires that goes to the pump and connecting it to your dimmer, and then taking the output from your dimmer and connecting it to the pump (where you just removed the other wire from).

Doing this should mean that the pump can be dimmed, stopped and started again without making any difference to the solenoid valve functionality.


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## mcrmfc

MrShades said:


> How or where have you wired the dimmer in?
> 
> You should be removing one of the wires that goes to the pump and connecting it to your dimmer, and then taking the output from your dimmer and connecting it to the pump (where you just removed the other wire from).
> 
> Doing this should mean that the pump can be dimmed, stopped and started again without making any difference to the solenoid valve functionality.


 @MrShades thank you a thousand times, I did warn you I was a numpty!!!

Yep all good now for some reason I thought the pump and solenoid were all just part of the pump circuit and it was either on or off with the solenoid de-energising when power comes off. But I see now how you can isolate the pump.

Thanks again!


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## MSM

Hummm my dimmer has arrived also, it has two inputs and two outputs.

Will have to have a play and see what I can do, hopefully can just get away with using one in and one out on the dimmer.


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## mcrmfc

Yes that's what I did...the two live connections essentially (the neutrals presumably would be for where you havr mains in out and lamp in out for its intended use case), but as you can see from my previous post you might not want to take my advice


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## MrShades

Yes, just use one of the pairs... one input and one output, and connect them inline with one of the cables to the pump.


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## AndyZap

I have finally completed this mod (incl the gauge which is externally mounted). But have problems with the dimmer. I've got this one first, the 300W version http://www.ebay.co.uk/itm/Relco-Black-Inline-Foot-Slider-Dimmer-Switch-ideal-for-Standard-Lamps-RL1104-/172705637004? . It did not last long - after a few days it started making unhealthy noise and the pump stopped. Maybe it is simply faulty, so sending it back. I have ordered a 500W version from Amazon https://www.amazon.co.uk/dp/B005ERPJA0/ref=wl_it_dp_o_pC_nS_img?_encoding=UTF8&colid=1YYYJCSHP6G82&coliid=IEXJLEKKIO0IL - which was mentioned in another "dimmer thread".


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## mcrmfc

AndyZap said:


> I have finally completed this mod (incl the gauge which is externally mounted). But have problems with the dimmer. I've got this one first, the 300W version http://www.ebay.co.uk/itm/Relco-Black-Inline-Foot-Slider-Dimmer-Switch-ideal-for-Standard-Lamps-RL1104-/172705637004? . It did not last long - after a few days it started making unhealthy noise and the pump stopped. Maybe it is simply faulty, so sending it back. I have ordered a 500W version from Amazon https://www.amazon.co.uk/dp/B005ERPJA0/ref=wl_it_dp_o_pC_nS_img?_encoding=UTF8&colid=1YYYJCSHP6G82&coliid=IEXJLEKKIO0IL - which was mentioned in another "dimmer thread".


Interesting I also have that Relco one...haven't tried it in anger as I am also doing a preheat mod at the same time. Wonder if mine will follow the same path.

Let us know how you get on with your new one!


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## mcrmfc

Well have done about 6 shots with slow ramp up to 6bar and then hold.....wow is all I can say, has taken away the sourness and really brought through the sweetness...pucks also look in better shape.

But...then as with @AndyZap my shitty relco dimmer has stopped working.

I have ordered this one from Amazon:

https://www.amazon.co.uk/dp/B001B4VIUK/ref=cm_sw_r_cp_awdb_fVIvzbFZEAFA5

Crap reviews but 500w and I can get it by tomorrow!

@AndyZap let's compare notes


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## AndyZap

The 500W I've got from Amazon is by Relco as well. The website does not mention the min load value, but in the manual it says 100W-500W, i.e. the pump does not present enough load. Tried it, and indeed it does not control the pressure well. So this one is going back.

@mcrmfc - all bets are on yours!


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## MSM

I have something like this...

AC 220V SCR adjustable Voltage Regulator Motor Speed 2000W Controller

http://www.ebay.co.uk/itm/AC-220V-SCR-adjustable-Voltage-Regulator-Motor-Speed-2000W-Controller-B252-/122560736196









Not installed yet - not sure it works yet either.


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## AndyZap

BTW, https://www.varilight.co.uk/ makes a huge range of dimmers. Many of them are specially designed for LED or halogen, but the V-DIM and V-PRO models might work with the pump. Has anyone tried these? E.g. https://www.tlc-direct.co.uk/Products/VLHDL3S.html - 60W-400W. I also like the on/off push switch - easy to do pre-infusion without changing the dimmer settings.


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## mcrmfc

Whatever you do don't get the one I linked to, worse than the relco, worked once...then smoke...


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## AndyZap

Thanks for letting me know. I've just ordered V-DIM to try ...


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## mcrmfc

Nice will be interesting to see how that one behaves!

Take 3 for me is going to be a variation on a theme of motor speed controllers:

220V 1500W Modulation AC Motor Speed Control Switch Governor White https://www.amazon.co.uk/dp/B00LXA6HY4/ref=cm_sw_r_cp_apa_TBbwzb4VP5W9J

Don't hold out great hope...


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## MSM

So just thrown this together quickly, there is a slow buildup to 6 bar and then reduces to around 4 while extracting

Stupid question, am I looking at a 6 bar shot or a 4 bar?

Will post a video when I manage to print a small case for the dimmer.


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## mcrmfc

Sounds promising @MSM, guessing you might need to adjust in shot to hold the 6 bar...if that's what you are going for...i like this post as it's vaguely empirical

http://compoundcoffee.com/experiments/12_Brew-Pressure-Impact-Sidamo-Guji


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## AndyZap

The Variilight' V-DIM https://www.tlc-direct.co.uk/Products/VLHDL3S.html does not work at all. With any dimmer setting I see 10 bar from the pump, as if the dimmer did not have any impact on the pump. At least all the other dimmers I tried can make the pump go to 0 bar, i.e. they do "something"

Any suggestions which one to try next?


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## mcrmfc

@AndyZap...damn sorry to hear that...I followed @MSM and got this motor speed controller:

220V 1500W Modulation AC Motor Speed Control Switch Governor White https://www.amazon.co.uk/dp/B00LXA6HY4/ref=cm_sw_r_cp_apa_MX0yzbX06PGA5

Chose this one as it is in plastic case so a little more safe than some others.

So far it's behaving very very well much as per MSMs description. Get the full range and easy to control. Also you have the click off as well which is useful.

Still worried I am speaking too soon though!


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## AndyZap

@mcrmfc - thank you, will order this one as well


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## MSM

Glad you have one that is working.

The one I have is behaving, only really get a chance to use it at the weekend while I am at home so it has not had much use.

The one I bought does not have a click off which might be worth noting.

I have managed to print a little case for it... still to put it all together - maybe tonight!


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## AndyZap

@mcrmfc - I am still waiting for the speed controller you recommended (seems Amazon takes its time to deliver when dealing with non-Prime customers







. Just wanted to ask about the controller wiring in the meantime, as some people complained that the instructions are not clear. Did you use 2 wires to connect (i.e. as for a dimmer, just to plug it in between the pump and one of the original wires connected to the pump) - or 4 wires, i.e. 2 wires to the pump + 2 wires to the original pump connectors? Which connectors on the controller are used? Thanks a lot!


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## MSM

The one mcrmfc links to looks like it only has two wires?

The one I have had 4 terminals, the two outside ones bypassed the dimmer, but it worked as expected when using the two inside terminals.


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## MSM

Dimmer and pressure gauge fitted.


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## mcrmfc

Looking very very nice @MSM really neat and tidy job, loving thr printed case as well.

@AndyZap there were no instructions provided with my controller and obvs both wires are blue.

I just hit and hoped.


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## MrShades

MSM said:


> Dimmer and pressure gauge fitted.
> 
> View attachment 27913


That looks as "Frankengaggia" as one of my Classics! Nice job.

Should really have been fitted as an option to the Back-to-the-Future De Lorean. ;-)

A


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## MSM

Thanks all, just added a remote for the lights (squeezed into the dimmer box)... because ... umm not sure why!


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## mcrmfc

@AndyZap - how did the motor speed controller behave for you?

I am probably going to regret saying this but mine is proving brilliant. The preinfusion makes such a difference, coupled with my recent grinder upgrade and good distribution I can get great consistency.

For the lighter roasts the ability to run at 5-6 bar annecdotally seems to produce beautiful sweet but not overly acidic shots.


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## rob177palmer

Does everybody install a pressure gauge to accompany the dimmer mod, so you know what pressure you are running?

Or is it good enough to measure pressure using a temporary portafilter gauge and mark off the pressure on the dimmer as reference when spinning the dimmer?


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## mcrmfc

rob177palmer said:


> Does everybody install a pressure gauge to accompany the dimmer mod, so you know what pressure you are running?
> 
> Or is it good enough to measure pressure using a temporary portafilter gauge and mark off the pressure on the dimmer as reference when spinning the dimmer?


You really do need the panel mounted pressure guage to make it worthwhile.

That said you could still benefit from the preinfusion aspect. You will notice by just opening the pump circuit without activating the solenoid water will start coming gently through the group, then you can engage the pump a little...wait 5 or so seconds then give it full whack.

But you know you will want the pressure guage anyway


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## rob177palmer

mcrmfc said:


> But you know you will want the pressure guage anyway


That is certainly true!! Trying to persuade myself to do the only simple mod at a time


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## rob177palmer

Have people managed to mount the switch inside the casing with the dial poking through a hole (similar to the steaming valve)?


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## AndyZap

@mcrmfc - I know exactly what you mean







Each time I say that I am happy with my mods, something goes wrong. Let me try to say it again: the motor speed controller is working really well









@rob177palmer - cannot comment, as I have Gaggia Baby which does not have much space inside, so all my controls (SSRs, PID, dimmer and the pressure gauge) are sitting outside making a little "control tower". But definitely the pre-infusion / 6 bar shot has made the major difference to the coffee taste - everything is somehow much better balanced (to my taste!)


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## mcrmfc

Good stuff!

@rob177palmer fitting it like that should be trivial...you would still need to hole saw an appropriate size hole and then just mount from thr inside and wire up. Just ensure proper earthing if the case of the speed controller is metal.


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## Slouch

I recently acquired a router speed control. Original plan was to use it for my roaster. Would anybody know if that works out in the same manner as this mod?


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## mcrmfc

Slouch said:


> I recently acquired a router speed control. Original plan was to use it for my roaster. Would anybody know if that works out in the same manner as this mod?


I am no expert but assuming you check it is AC and appropriate Volts and Watts rating then most probably.

Our collective experience is that these motor or fan speed controllers are a lot better bet than traditional dimmers.


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## Slouch

mcrmfc said:


> I am no expert but assuming you check it is AC and appropriate Volts and Watts rating then most probably.
> 
> Our collective experience is that these motor or fan speed controllers are a lot better bet than traditional dimmers.


People use it for 1500W popcorn poppers. I think a Gaggia Classic is similarly rated. Will give it a go.


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## dev

Would it possible for someone to put together a more detailed version of this mod. Information on the internet is quite fragmented and not entirely helpful since there are quite a few deviations.


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## AndyZap

I recommend reading this thread, and these two:

http://coffeeforums.co.uk/showthread.php?20477-Gaggia-Preinfusion-Dimmer-amp-Panel-mount-Guage-mod&highlight=gaggia+dimmer and

https://coffeeforums.co.uk/showthread.php?34653-Gaggia-Classic-Pump-Replacement-Invensys

This would give you all the references how to proceed.

Basically there are two parts to the mod: 1. fitting a dimmer + Invensys pump and 2. Fitting the pressure gauge. Make sure that 1. works well, you can check the pressure with the PF gauge (and simulate the shot by opening the steam valve by a tiny bit).

The pump I used is this one:

http://www.ebay.com/itm/321769453659

and the best dimmers seems are the Motor Speed controllers like these on Amazon:

https://www.amazon.co.uk/dp/B00LXA6HY4/ref=cm_sw_r_cp_apa_TBbwzb4VP5W9J

https://www.amazon.co.uk/sourcingmap%C2%AE-Electric-Voltage-Regulator-Controller-x/dp/B01MG9CFKU/ref=pd_sbs_60_4?_encoding=UTF8&psc=1&refRID=0EKJFKWFFXR5C9S5AY7D

If you happy with 1, then proceed with fitting the gauge. I actually have it outside (not much space inside the Baby Gaggia) - this makes the 2. really easy, as you do not need to drill the case.

Hope this helps!


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## DaveP

I was just about to do this mod, but then I read an old post from MrShades about 6 bar being rather nice over 17.5g

So I adjusted the opv to a static pressure at the portafilter of 7 bar 'ish and not only is Bob your uncle but MrShades is as well.

No swapping out of the pump, no electrical devices or alterations or twiddling of sliders / knobs, nice shot (albeit an extended pour time) and the very best of all is that it costs nuffing, zero, zilch.

It seems to be that the only possible tweeking would be in the grind size


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## dev

AndyZap said:


> I recommend reading this thread, and these two:
> 
> http://coffeeforums.co.uk/showthread.php?20477-Gaggia-Preinfusion-Dimmer-amp-Panel-mount-Guage-mod&highlight=gaggia+dimmer and
> 
> https://coffeeforums.co.uk/showthread.php?34653-Gaggia-Classic-Pump-Replacement-Invensys
> 
> This would give you all the references how to proceed.
> 
> Basically there are two parts to the mod: 1. fitting a dimmer + Invensys pump and 2. Fitting the pressure gauge. Make sure that 1. works well, you can check the pressure with the PF gauge (and simulate the shot by opening the steam valve by a tiny bit).
> 
> The pump I used is this one:
> 
> http://www.ebay.com/itm/321769453659
> 
> and the best dimmers seems are the Motor Speed controllers like these on Amazon:
> 
> https://www.amazon.co.uk/dp/B00LXA6HY4/ref=cm_sw_r_cp_apa_TBbwzb4VP5W9J
> 
> https://www.amazon.co.uk/sourcingmap%C2%AE-Electric-Voltage-Regulator-Controller-x/dp/B01MG9CFKU/ref=pd_sbs_60_4?_encoding=UTF8&psc=1&refRID=0EKJFKWFFXR5C9S5AY7D
> 
> If you happy with 1, then proceed with fitting the gauge. I actually have it outside (not much space inside the Baby Gaggia) - this makes the 2. really easy, as you do not need to drill the case.
> 
> Hope this helps!


Luckily enough my baby comes with the Invensys pump as standard. I'll just have to find a seller for the dimmer that delivers to Romania. That T Fit connector might be difficult to find locally.


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## rob177palmer

So after a fun day playing with Londinium levers at the recent Rave forum day, I am back to thinking about PI and pressure profiling on my Classic.

Both of the recommended spee contller a now unavailable, but I have found this one:

https://www.amazon.co.uk/Yeeco-Controller-Electronic-Regulator-Thermostat/dp/B0154I3ZUY/ref=sr_1_4?s=diy&ie=UTF8&qid=1512662094&sr=1-4&keywords=AC+Motor+Speed+Control

Which is already in a box, and seems to be a similar rating.

Any obvious discrepancies before I order?

Thanks guys


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## MrShades

rob177palmer said:


> So after a fun day playing with Londinium levers at the recent Rave forum day, I am back to thinking about PI and pressure profiling on my Classic.
> 
> Both of the recommended spee contller a now unavailable, but I have found this one:
> 
> https://www.amazon.co.uk/Yeeco-Controller-Electronic-Regulator-Thermostat/dp/B0154I3ZUY/ref=sr_1_4?s=diy&ie=UTF8&qid=1512662094&sr=1-4&keywords=AC+Motor+Speed+Control
> 
> Which is already in a box, and seems to be a similar rating.
> 
> Any obvious discrepancies before I order?
> 
> Thanks guys


Looks like it'd be worth a shot... have you already got an Invensys pump?


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## rob177palmer

MrShades said:


> Looks like it'd be worth a shot... have you already got an Invensys pump?


Yep - had to replace mine a short while ago when the cleaners left the machine pumping dry! Went with the invensys expecting to have done this sooner.

I'll read back through the thread for how to wire this in


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## rob177palmer

So order placed for the motor controller, should arrive week today.

Now just hope I don't screw up the wiring and kill my Classic ahead of the busy Christmas espresso rush!!


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## rob177palmer

Okay, motor controller arrived (slightly battered) but looks to be fully functional and quite smart box.

As per the others people have bought, this has four terminals (but no wiring diagram). I am guessing it will be the two middle connectors as per the diagram posted previously.

Here's the wiring diagram for the classic:

https://wiki.wholelattelove.com/images/a/aa/CLASSIC_Electrical_Diagram.pdf

I'm intending to disconnect the red wire from the pump, run this to one of the middle controller terminals, then from the other middle terminal back to the pump.

Does that sound correct?


----------



## AndyZap

This looks correct. You cannot do any damage to the machine, as the controller does not have own mains power and you insert it basically inline, in the gap you make in the red (live) wire. Also it is hard to damage the controller, if it is designed to work with the mains voltage.


----------



## rob177palmer

Thanks @AndyZap.

Good to know I am looking at the right wires. Unfortunately my Classic doesn't seem to have the "convenient connection" mentioned in this write-up:

http://www.gaggiausersgroup.com/index.php?action=ezportal;sa=page;p=90


----------



## AndyZap

I used two spade connectors from Maplin (one male, one female - ideally a fully insulated one. ) to attach to the controller' wires. The female one goes to the pump, and the male can be inserted into the female on the original red wire. Then you do not need to cut the existing red wire. Make sure it is all properly insulated (e.g. with a tape), so you do not have any "naked" metal at main voltage. Also note the connectors have different sizes (blue, red, etc), so select the one to match your wires diameter


----------



## ashcroc

AndyZap said:


> I used two spade connectors from Maplin (one male, one female - ideally a fully insulated one. ) to attach to the controller' wires. The female one goes to the pump, and the male can be inserted into the female on the original red wire. Then you do not need to cut the existing red wire. Make sure it is all properly insulated (e.g. with a tape), so you do not have any "naked" metal at main voltage. Also note the connectors have different sizes (blue, red, etc), so select the one to match your wires diameter


Electrical tape works but heatshrink is tidier.


----------



## rob177palmer

All wired in and seems to be working well.

Have tried to mark off pressures with a portafier-mounted pressure gauge until i have installed a panel mount gauge. However, the pressure doesn't seem consistent between pours, but I am sure I can manage "low pressure" (regardless of how many bars that actually is), then increase pressure.

Very excited to see how this performs tomorrow.


----------



## rob177palmer

Also managed to descale the steam valve assembly to stop the drip, so productive evening of tinkering!


----------



## haz_pro

Good job, would love to see a video.


----------



## rob177palmer

I've been a little quiet on the review as trying to work out just what is going on!

The mod works beautifully. I can definitely say that the puck is better extracted and expanded - it stays much more whole when knocking out.

HOWEVER, the coffee now tastes shocking. Incredibly metallic.

My concern in posting this fact is:

1) it could be user error - me offering too long a low pressure PI, or

2)I have been at deaths door (serious man flu) since Thursday so maybe my taste is off? Or,

3) beans stale? They were frozen after resting but have been out of the freezer for 10-14 days now. So past it.

4)maybe the grinder is in need of cleaning, or

4) something to do with me stripping and descaling the steam valve set up.

That's my list of suspects. I think user error definitely contributes sometimes, but even pulling a shot with the dial wound up to full pressure gives a slight metallic taste.

On the positive side I really like using the dial mod - just hope I can get the good coffee taste back alongside the improved texture I have achieved.

....just when I thought I was starting to know what I was doing!!


----------



## rob177palmer

So basically I need to knock the suspicions off my list of causes one by one.

Grrrrr


----------



## haz_pro

If you run the machine at the pressure you used previously for the whole shot. Do you still taste it? If so, you can rule out a couple of them options.


----------



## rob177palmer

haz_pro said:


> If you run the machine at the pressure you used previously for the whole shot. Do you still taste it? If so, you can rule out a couple of them options.


I have tried this and think I can still taste it slightly, but need to get myself properly better to rule out illness as the cause! I'll keep trying over the next couple of days. Have now deep cleaned the grinder and changed for fresh beans so that's two causes knocked off the list!

Will report back when I have got to the bottom of this.


----------



## rob177palmer

Okay, feeling slightly better today so lined up three shots:

1) standard.

2) Moderate PI then ramp up pressure

3) slightly longer PI then full, then progressive reduction in pressure towards end of pour.

Mouthfeel - #1 was fine, #2 better #3 much more syrupy. Very impressed with that element.

Pour - naked extraction on all. #3 was noticeable that the coffee immediately went to a smooth mousetail. No dripping from different areas of the puck as usual and an even colour across the basket. The PI definitely allowed a more even flow.

Taste - the overall taste was somehow more intense with #3 than the other two, #2 was midway. That said I could taste the "oranges and raisins" with each.

Now, I think the negative flavour "metallic" is actually an increased acid aftertaste, and is definitely more prominent in #3 than the other two, and midway in #2. I don't like the aftertaste as much with the PI shots.

So, in conclusion (sorry it's longwinded) PI improves the extraction and mouthfeel but gives too acidic flavour with this bean. Can anyone help me trouble shoot how to reduce this? Acid I telltale of channelling, but that is not the case here.

Can I adjust PID temp to compensate?

Am i maybe using too long a PI?

Any tricks / suggestions that the more successful users have found?

Thanks all.


----------



## joey24dirt

I'm liking this thread. I've just done the same mod on my DTP, although they have 10 seconds pre infusion built in.

I definitely noticed a difference with my shots.

Very interesting seeing how you get on with it


----------



## AndyZap

Try reducing the PID temperature. I had 94 on PID display (+8 degrees offset), now use 93 and it tastes better.

It could depend on the coffee as well. My latest one were all fruity (like Finca San Francisco from Foundry or the December from Has Bean subscription). Seems that long PI + low pressure shot with large ratio (18g VST into 41g) works well with these coffee. First I press the ON on the machine with the pump switched OFF (I have the on/off switch on the dimmer), so the water drops on the puck. Next I switch on the pump on the lowest dimmer setting, it takes about 15 sec for the first drops to appear, with the pressure reaches about 2 bar. Then I increase the pressure to 6-7 bar - all it takes just a slight turn on the dimmer dial, i.e. almost no change in the pump noise.

Hope this helps. Take it with a pinch of salt, of course - I am still very new to this.


----------



## rob177palmer

Cheers for the comments Andy - this got me thinking and I found this http:// https://www.fivesenses.com.au/blog/brew-temperature-and-its-effects-on-espresso/article, within it:

"Lowering the brew temp will enhance acidity in coffee/raising the brew temp will decrease acidity in coffee."

I'll dial up the PID tomorrow for some more back to back testing. Be interesting to see what difference that makes.

Really helpful to read your workflow.


----------



## rob177palmer

This image:










Is also interesting - if the acidic constituents come through early with sugars later, Andy's comment on a longer shot working might also be key here.

It would be interesting if adding PI means I need to go longer than my usual foolproof 1:2 (for me that is 15:30g).

I also tend to err on the slower side of extraction, preferring around 40 seconds for a good shot, but that is all on the basis of full pressure throughout the pull.

This dimmer seems to be opening up a whole new world of possibilities (read confusion!!!!)


----------



## rob177palmer

Yesterday's attempts were a disaster. Machine nearly went out of the window.

Good night's sleep and dialled the grinder back in on normal pulls then tried again.

First pressure modulated shot gave massive channelling so sink shot

Second one tried a ramped pressure throughout - started at zero pressure then slow ramp up full pressure from ½ way thru to the end. FIRST ONE THAT WASN'T DIRT!!

So the conclusion I have been trying to avoid is that, somehow, my pressure modulated shots are suffering massive channelling issues. So, what the hell am I doing??

I'm wondering if a lot of water is entering the puck and liquifying it and allowing the water to channel when I ramp up.

I'm going to try a more progressive ramp up of pressure next time again to see if helps.


----------



## rob177palmer

So it's definitely channeling and the slow ramp from zero to full didn't work this time.

FFS


----------



## kennyboy993

rob177palmer said:


> This image:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Is also interesting - if the acidic constituents come through early with sugars later, Andy's comment on a longer shot working might also be key here.
> 
> It would be interesting if adding PI means I need to go longer than my usual foolproof 1:2 (for me that is 15:30g).
> 
> I also tend to err on the slower side of extraction, preferring around 40 seconds for a good shot, but that is all on the basis of full pressure throughout the pull.
> 
> This dimmer seems to be opening up a whole new world of possibilities (read confusion!!!!)


Great image. What article is it from please Rob?


----------



## joey24dirt

It would be interesting to see what it was like using the DTP standard profile, or have you done that already? 

Basically around 1bar ish for ten seconds then raise the pressure to about 6-7bar.


----------



## rob177palmer

kennyboy993 said:


> Great image. What article is it from please Rob?


I did try to quote directly but tap talk couldn't pull thru the image properly.

Here was the article I found http:// https://prima-coffee.com/blog/video-pressure-vs-flow-espresso-extraction.

After reading this I was inspired to go on an Internet crawl looking at slayer machines, so be warned!!


----------



## rob177palmer

joey24dirt said:


> It would be interesting to see what it was like using the DTP standard profile, or have you done that already?
> 
> Basically around 1bar ish for ten seconds then raise the pressure to about 6-7bar.


Does your DTP do this automatically from pushing the brew button? Interesting - they are quite clever machines for the price.

I'll try tomorrow and see again. I was ready to give up with this whole PP thing, but then I managed the one shot that earlier that worked very well. GRR!!

I have recently been teaching myself to "grind fine tamp light", and I wonder if this isn't working with the PI. It just flipping gushes out the naked PF once you turn up to anything like normal pressure. Very frustrating and have wasted half a kilo of beans so far!

Funny thing is I wanted to try this after reading that the PI systems on commercial machines made he shot more forgiving - I have found the exact opposite!


----------



## joey24dirt

rob177palmer said:


> Does your DTP do this automatically from pushing the brew button? Interesting - they are quite clever machines for the price.
> 
> I'll try tomorrow and see again. I was ready to give up with this whole PP thing, but then I managed the one shot that earlier that worked very well. GRR!!
> 
> I have recently been teaching myself to "grind fine tamp light", and I wonder if this isn't working with the PI. It just flipping gushes out the naked PF once you turn up to anything like normal pressure. Very frustrating and have wasted half a kilo of beans so far!
> 
> Funny thing is I wanted to try this after reading that the PI systems on commercial machines made he shot more forgiving - I have found the exact opposite!


Firstly I hope you don't mind me bringing my DTP to the gaggia thread lol.

Yeah when I turn to brew it does a 10 second pre-infusion then ramps up to about 8 bar depending on the grind. What I have been doing is waiting for the pre to finish and then dialling the pressure back to sit at 5 bar. When I don't do this I have been getting spritzing but when I do then yes the shot it way more forgiving.

Taste wise for me is much better and I have really enjoyed the shots so far.

As for my grind, it's not mega fine, but fine enough to fit a standard 1:2 30secs type of shot. Then from there I messed with the pump pressures.

Do you have a gauge on your machine so you can see what you're getting? Apologies if this info is already in the thread haha


----------



## rob177palmer

joey24dirt said:


> Firstly I hope you don't mind me bringing my DTP to the gaggia thread lol.
> 
> Yeah when I turn to brew it does a 10 second pre-infusion then ramps up to about 8 bar depending on the grind. What I have been doing is waiting for the pre to finish and then dialling the pressure back to sit at 5 bar. When I don't do this I have been getting spritzing but when I do then yes the shot it way more forgiving.
> 
> Taste wise for me is much better and I have really enjoyed the shots so far.
> 
> As for my grind, it's not mega fine, but fine enough to fit a standard 1:2 30secs type of shot. Then from there I messed with the pump pressures.
> 
> Do you have a gauge on your machine so you can see what you're getting? Apologies if this info is already in the thread haha


This sounds very much like where i have started - same grind. I'm going to try a gorilla tamp today and see the result, but that sort of defeats the object of this if you ask me. Will also try not exceeding 6/7 bar and see if that helps.

No pressure gauge yet. Was going to fit a front panel mount gauge if I keep this dimmer. I have measured the pressures throughout the range of the dimmer tho and marked off what I am pumping at.


----------



## sage9984

Hey guys ,

New to the forum and in the process of doing the dimmer mod. I purchased this dimmerROK Micro AC 110V 4000W Voltage Regulator SCR 110VAC Dimmer Speed Controller Temperature Governor Power Monitor Dimming Monitor https://www.amazon.com/dp/B00BXUCWQG/ref=cm_sw_r_cp_apa_HfZQAbBGN952H

When I connect the wires on the outside terminals, I can control the pump, but it is sporadic. Even when the dimmer is all the way low, water is still dripping from the group head. The as I turnthe knobon the dimmer, I can hear the pump turn on and the flow increasing and at about 40% the pump cuts out and water goes back to same level as when knob is at zero and then again flow picks up as I turn past 60%. Is this normal behavior?

Also I have the red wire from the Brew switch connected to the far left terminal (farthest away from the knob) and the output to the pump at the far right terminal (closest to the knob). When I interchange the connections, the same thing happens. Is this normal?

FYI: I have a ulka pump.

Please help.


----------



## joey24dirt

sage9984 said:


> Hey guys ,
> 
> New to the forum and in the process of doing the dimmer mod. I purchased this dimmerROK Micro AC 110V 4000W Voltage Regulator SCR 110VAC Dimmer Speed Controller Temperature Governor Power Monitor Dimming Monitor https://www.amazon.com/dp/B00BXUCWQG/ref=cm_sw_r_cp_apa_HfZQAbBGN952H
> 
> When I connect the wires on the outside terminals, I can control the pump, but it is sporadic. Even when the dimmer is all the way low, water is still dripping from the group head. The as I turnthe knobon the dimmer, I can hear the pump turn on and the flow increasing and at about 40% the pump cuts out and water goes back to same level as when knob is at zero and then again flow picks up as I turn past 60%. Is this normal behavior?
> 
> Also I have the red wire from the Brew switch connected to the far left terminal (farthest away from the knob) and the output to the pump at the far right terminal (closest to the knob). When I interchange the connections, the same thing happens. Is this normal?
> 
> FYI: I have a ulka pump.
> 
> Please help.


Isn't your machine 240v? That dimmer you have linked is 110v


----------



## ashcroc

IIrc the ulka pumps aren't too keen on dimmers. Inversys pumps are supposed to work better.


----------



## joey24dirt

You need to take the wires going to the pump and connect to the 'AC in' and then run new wiring from the output to your pump. That's how mine is wired up in my machines.


----------



## sage9984

I am in the US so that's why I bought 110v


----------



## sage9984

Yea that's what I have done. But when I interchange the wire, I get the same result.


----------



## sage9984

ashcroc said:


> IIrc the ulka pumps aren't too keen on dimmers. Inversys pumps are supposed to work better.


Ok. I have place an order for a invensys pump. Thanks for the heads up. I wonder if I am wiring the switch up correctly.


----------



## dev

What pump have you settled on?


----------



## GrahamS

with regard to the two different pumps, and the idea the Ulka doesn't work as well as the Invensys with a dimmer, it is almost certainly the other way round, the dimmer doesn't work well with the Ulka.

Many years ago I was cobbling up a circuit to warn my parent's of the back gate opening at night. I took a remote IR sensor designed to switch on an external light, but actually used it to switch a small transformer on which then powered an alarm. the result was the transformer was on all the time.

the reason in that case was that in parallel with the switch is a snubber network that stops annoying clicks from light switches - it consists of a resistor and capacitor, and presents quite a high impedance to ac, but does allow enough current to flow to power up a very low power evice, where a 100w bulb would swamp it.

I suspect the same is happening with the dimmer, the smaller pump draws less power so the triac is being bypassed, meaning the dimmer doesnt have full control. I'm going t stick a resistor in parallel with the pump to increase the load and see if that improves control. results to follow.....

I've also got a timer in parallel with the dimmer, so it is bypassed after 6 seconds


----------



## joey24dirt

GrahamS said:


> with regard to the two different pumps, and the idea the Ulka doesn't work as well as the Invensys with a dimmer, it is almost certainly the other way round, the dimmer doesn't work well with the Ulka.
> 
> Many years ago I was cobbling up a circuit to warn my parent's of the back gate opening at night. I took a remote IR sensor designed to switch on an external light, but actually used it to switch a small transformer on which then powered an alarm. the result was the transformer was on all the time.
> 
> the reason in that case was that in parallel with the switch is a snubber network that stops annoying clicks from light switches - it consists of a resistor and capacitor, and presents quite a high impedance to ac, but does allow enough current to flow to power up a very low power evice, where a 100w bulb would swamp it.
> 
> I suspect the same is happening with the dimmer, the smaller pump draws less power so the triac is being bypassed, meaning the dimmer doesnt have full control. I'm going t stick a resistor in parallel with the pump to increase the load and see if that improves control. results to follow.....
> 
> I've also got a timer in parallel with the dimmer, so it is bypassed after 6 seconds


I've found the dimmer to work fine with an ulka pump on the sage dtp. I'm wondering if this is because there's more electronics inside controlling things and increasing the load as you mention.

What differences have been noticed between the two pumps when using in the classic?


----------



## dev

Having tried about 5 dimmers and 2 pumps here are my conclusions: not every cheap 2000w eBay dimmer works as advertised and some don't work at all.

My machine came with the Invensys CP3, noisy but very responsive to dimming, and currently I'm using an ARS Smart 15 which while silent it doesnt work at all with the same dimmer but i like the slower flow it provides.

If your goal is to control the actual flow and the time in which the coffee puck saturates, I would recommend the CP3 pump and a working dimmer. With this setup I'm able to control the preinfusion between 5 and 20s at basically 0 bar. After that I "open" the dimmer and once the coffee puck saturates you will be extracting at the pressure set by the OPV, I've got mine set at 8 bar with the blind filter and it goes to about 7.5bar during a shot, and after that pressure is reached you can dim the pump to slow down the pour.

You might be wondering why would anyone go through this ? The answer is because lightly roasted coffee doesn't play well with a classic extraction, ie 5 second before max pressure and a 20 second pour after that.

If one wishes to take this even further you can add a needle valve and a 3 way solenoid valve in order to achieve a better controlled preinfusion, a la Slayer.


----------



## GrahamS

I have put a 3300R 25W resistor in parallel with the pump, and I have full control. this is withthe standard pump and the cheapest dimmer i could find


----------



## MrShades

GrahamS said:


> I have put a 3300R 25W resistor in parallel with the pump, and I have full control. this is withthe standard pump and the cheapest dimmer i could find


That's with an Ulka @GrahamS ?

Very useful tip if it is.


----------



## GrahamS

I assume so @MrShades. without the resistor i had some control, but limited. with it, full control from 0 to 100%

it's either the inductive load the dimmer doesn't like, or the light load, but it definitely works, and cost 50p


----------



## dev

That's a 3300 ohms and 0.25w resistor?


----------



## ashcroc

dev said:


> That's a 3300 ohms and 0.25w resistor?


Been a while since I went to college but I think that should be orange orange red gold?

It's good to see there's still innovation with these old machines. Will definitely be trying this once I have my pressure gauge installed.


----------



## GrahamS

NOOOOO! 25W !!!!

240/3300 = 7mA

0.007 x 0.007 x 3300 (I2R) = 16W

a 0.25 would disappear in a puff of smoke

https://www.ebay.co.uk/itm/232738494106


----------



## GrahamS

nest innovation, the dimmer has a variable resistor for control - which just gives a voltage - repalcee with an opto isolated transistor and resistor, and control with an arduino, so full pressure profiling is available, with shot time etc.


----------



## Hasi

GrahamS said:


> nest innovation, the dimmer has a variable resistor for control - which just gives a voltage - repalcee with an opto isolated transistor and resistor, and control with an arduino, so full pressure profiling is available, with shot time etc.


----------



## Olek

Hello all

just registered, as I find your forum to be much advanced, technically speaking , in regard of the few I did see yet.

I just received my 6?5 € dimmer and installed it for tests in 5 minutes, on my Reneka duo (recent Ulka UP5)

IT seem to do the job even if not as smooth as it could be probably. What do you think ?


----------



## lake_m

Yes they do work on vibration pumps. A very cheap way to get pre infusion and some form of flow profiling on machines that do not have that option.

Here is mine installed in housing with a bypass switch.


----------



## Olek

lake_m said:


> Yes they do work on vibration pumps. A very cheap way to get pre infusion and some form of flow profiling on machines that do not have that option.
> 
> Here is mine installed in housing with a bypass switch.
> 
> View attachment 31756
> , I will see how to


 A good option indeed . The thread did begun on the better functionning of Invensys pumps with a dimmer regulation. Admittedly my Ulka can give 3bar minimum with the dimmer, which is a bit high for pre infusion, I wish I could obtain 1-2 bar , may be with that parallel mounted resistor ? (I do not get the logic there but will try to understand)


----------



## Olek

MrShades said:


> GrahamS said:
> 
> 
> 
> I have put a 3300R 25W resistor in parallel with the pump, and I have full control. this is withthe standard pump and the cheapest dimmer i could find
Click to expand...

 I plan to do that , is that type of resistor OK ? https://www.digikey.fr/product-detail/fr/te-connectivity-passive-product/HSA253K3J/A102141-ND/2054197

Thank you


----------



## AndyZap

The resistor looks correct. Also make sure that you have a bypass switch, to switch the pump off completely - I have found this is very useful. Some dimmers has this feature, if you do not have it - just add the standard light switch, as on the picture you refer to in your post.

Also regarding the pre-infusion pressure. To to mimic a lever machine profile, I used the pre-infusion at the lowest dimmer settings (about 2 bar, flow about 1mL/s), then after 7-10 sec increased the dimmer setting to go to 7-8 bar. If you do not change the dimmer setting, the pressure will naturally decline as the puck gives less resistance to water, so you have nice lever profile. Well, as I realised recently, this is not what the lever machines do.The flow needs to be very high at start. This helps to saturate the puck with water quickly, but what is most important, this compresses the pack and thus reduces the channeling, So now I do the following: run the pump at max flow for a few sec, then switch off the pump, or set the dimmer to min settings. This gives about 3 bar pressure. Wait a few (5 ... 20) sec, Run at 8 bar, declining to about 3 bar (do not need to change dimmer setting to get that, as I mentioned before). Seems give much better tasting shots.

Another recent change (not related to dimmer) - I use two IMS shower screen (the mesh and GA200IM) on the top of each other, the mesh outside. This calms the flow at the start of the shot, again seems helps to avoid channeling.


----------



## KTC

Hello lovely people! This form seems to be a treasure trove of information on the dimmer mod, especially for a newbie like myself. The inputs about the resistor and the motor speed controller seem invaluable. I want to do this on the Classic 2020. Presently, I haven't modded the OPV so I'm assuming I'm way over 9 bar. I'm hoping this mod can mitigate the need for OPV adjustment, in addition to enabling pre-infusion and flow control. If someone would be so kind as to clarify a few doubts I have -

This is the resistor I could find - 3.3 kOhms 25 W Wirewound Resistor and this is the controller - Motor Speed Controller Would these be okay?

Being an utter electronics noob, I have no idea how to connect the resisitor in parallel. How and where would the circuit be? My plan was to introduce the controller on the wire between the brew switch and the pump. Now I'm confused. I'd be grateful for any guidance. 🙏


----------



## MrShades

KTC said:


> Hello lovely people! This form seems to be a treasure trove of information on the dimmer mod, especially for a newbie like myself. The inputs about the resistor and the motor speed controller seem invaluable. I want to do this on the Classic 2020. Presently, I haven't modded the OPV so I'm assuming I'm way over 9 bar. I'm hoping this mod can mitigate the need for OPV adjustment, in addition to enabling pre-infusion and flow control. If someone would be so kind as to clarify a few doubts I have -
> 
> This is the resistor I could find - 3.3 kOhms 25 W Wirewound Resistor and this is the controller - Motor Speed Controller Would these be okay?
> 
> Being an utter electronics noob, I have no idea how to connect the resisitor in parallel. How and where would the circuit be? My plan was to introduce the controller on the wire between the brew switch and the pump. Now I'm confused. I'd be grateful for any guidance. 🙏


 The resistor looks OK, yes - and the speed controller is a bit of an unknown but also looks OK (I've used similar, but not the same).

So - unless they are both a huge amount of money, they seem worth the risk - try them and let us know how you get on (both with and without the resistor in parallel with the pump) on here.


----------



## KTC

MrShades said:


> The resistor looks OK, yes - and the speed controller is a bit of an unknown but also looks OK (I've used similar, but not the same).
> 
> So - unless they are both a huge amount of money, they seem worth the risk - try them and let us know how you get on (both with and without the resistor in parallel with the pump) on here.


 That's the plan. About the resistor - I don't know how to go about connecting it in parallel with the pump. Using the controller alone is clear - wire from brew switch -> controller -> pump. What to do with the resistor?


----------



## MrShades

There are two connectors on the pump - each one goes to a power cable. You need to put the resistor between the two connectors

(not sure if this will work) RRR is the resistor, and PPP is the pump

LIVE------------------R-----P

R P

NEUTRAL-----------R-----P


----------



## KTC

MrShades said:


> There are two connectors on the pump - each one goes to a power cable. You need to put the resistor between the two connectors
> 
> (not sure if this will work) RRR is the resistor, and PPP is the pump
> 
> LIVE------------------R-----P
> 
> R P
> 
> NEUTRAL-----------R-----P


 This is kinda what I was thinking too, from all the youtubing on series and parallel connections I did. Hope I don't end up blowing anything up!


----------



## Michael87

I've bought a simple brushed steel 400W light dimmer switch to try this mod, but can't figure out a clean way to mount it to the case. What has everyone else done?

I don't have a lot of room in the case with the PID and a pressure gauge! And there's a good 25mm of switch behind the front plate.


----------



## Skizz

Michael87 said:


> I've bought a simple brushed steel 400W light dimmer switch to try this mod, but can't figure out a clean way to mount it to the case. What has everyone else done?
> 
> I don't have a lot of room in the case with the PID and a pressure gauge! And there's a good 25mm of switch behind the front plate.


 Not got round to doing this on mine yet but planning to do it at same time as a pre-heater. Couple of things to consider from my own reading on the subject and speaking to an electrician friend:



Check your dimmer is rated for use in higher ambient temps. The inside of Classic can get pretty toasty when steaming and high temps can do interesting things to resistance/conductivity etc


Test the rig first before installing it. Be a shame to go drilling holes to find the system doesn't perform as expected and you can't find an alternative that'll fit the location you've chosen


Ensure you've earthed it correctly if mounting to the chassis. Be a shame to blow yourself across the kitchen in the name of coffee science 😉


Let us know how you get on 👌


----------



## shodjoe1

Guys,I'm just curious,I have PID ,dimmer switch on gaggia classic and I'm very happy with the results.My question is,Did anyone compared same coffee beans on HX or e61 machine?How massive or not big difference did you find in taste?

I don't know anyone who has ''another'' level machine,so never tasted other brew that from gaggia and same coffee beans for comparison.

Thanks


----------



## handonam

Hey all!

I was browsing this after I posted a question on the /r/gaggiaclassic group about the mod (

__
https://www.reddit.com/r/gaggiaclassic/comments/geyn9k
)

I've stumbled upon this board (and this thread particularly) for over a couple years, and decided I would finally jump in on the fun 

I just wanted to share what I did, in hopes to help someone else visually understand what's going on:

Imgur Gallery

Enjoy!


----------



## Skizz

That is incredibly helpful. Thanks so much! Looks very similar to the controller I've had in my ebay basket for a couple of months but I keep debating whether the voltage range is too high to get fine control, even with an inline resistor.


----------



## handonam

Skizz said:


> That is incredibly helpful. Thanks so much! Looks very similar to the controller I've had in my ebay basket for a couple of months but I keep debating whether the voltage range is too high to get fine control, even with an inline resistor.


 No problem! I also was debating on which dimmer to get exactly. I had a gut feeling that PWM speed dimmers are a much better bet than a typical light dimmer (at negligible difference in cost), and I've seen them used in high-power applications before. They're made for these fine-tune adjustments, even more so with the one I got off Amazon.









I just learned about the voltage range speed-pot (the blue box you see in the gallery I posted above). I increased it 10 whole clockwise turns in order for my bigger pot to start at 2bars of pressure when the big knob is at 0%.

Now, my potentiometer's 0% to 100% is the same as 2bar to 9bar. It's even more room for fine tuning than before. Rolling off the knob was already pretty sensitive: the pressure relief was really fast. I think this might be a bit better now.

Anyway, i just had another shot this morning. oooh boy it's syrupy and fantastic with a perfect extraction! Didn't record it because I only had one dose left, and wanted to focus on doing this right haha.


----------



## Cynary

I'm looking to add a dimmer to my gaggia, but I'm hoping to make it electronically controllable. I'd be interested to hear how the PWM motor controller one works. It seems similar to what was done here: http://int03.co.uk/blog/project-coffee-espiresso-machine/

With some research, though, I've found that phase control with some tweaks might be the best for these pumps, due to back-EMF concerns. Some interesting graphs here:

http://espresso-for-geeks.kalaf.net/features/pressure-profiling/

I did some research on how to build your own electronics for a phase control dimmer, but my first result (https://www.instructables.com/id/Arduino-controlled-light-dimmer-The-circuit/) led me to this:

https://www.aliexpress.com/item/32802025086.html

I ordered a couple of these, and will report back once I have them on how well they work / don't 

Has anyone else played with phase control dimming? What were your results like?


----------



## Michael87

accidental post and can't delete


----------



## Michael87

I've just ordered the same AC PWM dimmer, next challenge figure out how to mount it. I'm thinking rare earth magnet on the outside with wired going in through the rear vents...


----------



## handonam

Michael87 said:


> I've just ordered the same AC PWM dimmer, next challenge figure out how to mount it. I'm thinking rare earth magnet on the outside with wired going in through the rear vents...


 currently i have a very sticky mounting tape that's doing well. but i will drill a hole and mount it eventually


----------



## handonam

It's been a little over a week now. Out of all the mods I've researched and installed, I think this mod has helped really make this brewing *fun*. It's kind of pleasant to hear the noise of the pump actually becoming really quiet during pre-infusion and during the 'lever up'/rolling-back of the knob. it just makes extractions so much better to work with.

Mind you, I still haven't gotten the inline gauge to directly check the pressure yet. But, at this point, I kind of feel like I don't REALLY need it. I've mostly just eyeballed how the flow of the espresso is doing as I'm rolling it back.

I'm sure one day, I'll want to hook up my Arduino to better simulate this reliably. Probably more efficient. However, I feel it will take away the fun. Maybe this is like the flappy-paddle vs manual gearbox race car analogy: One will get you around the track faster and more precisely, while the other is a fun driving experience.

Ultimately, these Gaggia projects are meant *for the tinkerers to have fun*, giving us the ability to add controls that allow us to more directly influence the outcome. At least, that's my feeling about it .


----------



## Zeak

Heeey. Well this is a fun thread .) Was reading through it yesterday and decided to maybe give it a go. "Maybe" because it was pretty excruciating to see how this thing almost made *@rob177palmer* mad in retrospective.

My pump is not exactly an Invensys but it's still 65w. Guessing it'll do? This switch seems to be legit just need to figure out the case for it.

@handonam the Arduino bit got me super excited!


----------



## Olek

Hello,

I think the dimmer allow a slower ramp, pression wise, but it does not change the behavior of the pressure so much (there is a ramp in any case)

I did not notice a better extraction with the dimmer, but I am far from being an expert .

There is in the end 2 effective positions, I would say, minimum (checked with the pressostat ), then turn the knob to the max position.

Time is still 30 sec or little more eventually

I have the usual V4 pump, not avensys, I had to add a resistance to help the dimmer

Regards


----------



## handonam

Zeak said:


> Heeey. Well this is a fun thread .) Was reading through it yesterday and decided to maybe give it a go. "Maybe" because it was pretty excruciating to see how this thing almost made *@rob177palmer* mad in retrospective.
> 
> My pump is not exactly an Invensys but it's still 65w. Guessing it'll do? This switch seems to be legit just need to figure out the case for it.
> 
> @handonam the Arduino bit got me super excited!


 Yea, to be honest, @rob177palmer did make it seem like this was going to be very hard to do. In reality, it was one of the *easiest* things i'd done in the world of DIY electronics. But, that's in retrospective because guys like him paved the way to understanding the mistakes along the way.

I was originally also deterred that you'd need a pressure gauge around the pump to be able to use this mod. But, in reality, you don't need it. You may not even need a portafilter gauge as well (but it would be very helpful). Just have to eyeball what the drip is from the showerhead.

For a VERY ROUGH estimate, this is what i get for the amount of water flowing out into the cup, no portafilter or any resistance in the grouphead:

lowest setting: 16g of water @ 15sec
highest setting: 128g of water @ 15sec

i do plan on raising the lowest setting up some more (via the blue potentiometer) in the next few weeks


----------



## Michael87

handonam said:


> currently i have a very sticky mounting tape that's doing well. but i will drill a hole and mount it eventually


 It's just arrive in the mail, probably a stupid question but which of the four terminals do you connect the pump to? Two are "in" and two are "out", does it matter which?


----------



## Agentb

handonam said:


> For a VERY ROUGH estimate, this is what i get for the amount of water flowing out into the cup, no portafilter or any resistance in the grouphead:


 I'm interested to see how it all looks in the end 😎

Flow measurement with a shower-screen on or off, and if on / what make?

I'm assuming the OPV mod is done?


----------



## Yosuf

Hi there, so 3 things 

1, am I understanding my jargon correctly that this Dimmer switch mod essentially enables you to control the pressure for potentially the entire duration of the shot? That's what I'm after, a super manual experience where I have manual control.

2, I might have missed, but are there any videos of this dimmer switch mod being operated? I'd love to see someone operating the dimmer switch as the shot pours.

3, Maybe a crazy idea, but thats what I do best..., THEORETICALLY (and get as practical as you want...) ---> could something *other* than a dimmer switch be used to control pressure on a Gaggia Classic Pro? Say a lever , or some kind of a tap, etc.... As I said in my 1st point, I definitely want the ability to control pressure throughout my shot, but from a user-experience perspective, operating a tiny little dimmer switch just doesn't feel like it would be as satisfying to me... Wondering if any of the great minds here have thought/could think of other more tactile ways to control the pressure manually throughout the shot?
Cheers,

Yos

PS- Can't wait to share what I'm doing to my Gaggia Classic Pro with all of you soon !


----------



## Michael87

So I've hooked up the dimmer

AC 2000W Motor Speed PWM Controller Control Voltage Regulator Dimmer 110-220V

And it doesn't seem to be going low enough to have a noticeable effect on pressure. There is a variable dial, but I've just pulled 8 shots with it turned anywhere from 0 (far anticlockwise) up to 25 full rotations (in clockwise direction) with no significant difference in min pressure after moving the main control.

In the far anticlockwise you can hear the pump load dropping (which is nice and quiet) but still manages to attain around 9 bars measured with an in line pressure gauge between pump and OPV.

I'm wondering how this can be fixed.

I have an ivensys cp4/sp pump which might be the reason I'm getting different results. This is rated for 70W so maybe I need a lower power dimmer?


----------



## handonam

Yosuf said:


> Hi there, so 3 things
> 
> 1, am I understanding my jargon correctly that this Dimmer switch mod essentially enables you to control the pressure for potentially the entire duration of the shot? That's what I'm after, a super manual experience where I have manual control.
> 
> 2, I might have missed, but are there any videos of this dimmer switch mod being operated? I'd love to see someone operating the dimmer switch as the shot pours.
> 
> 3, Maybe a crazy idea, but thats what I do best..., THEORETICALLY (and get as practical as you want...) ---> could something *other* than a dimmer switch be used to control pressure on a Gaggia Classic Pro? Say a lever , or some kind of a tap, etc.... As I said in my 1st point, I definitely want the ability to control pressure throughout my shot, but from a user-experience perspective, operating a tiny little dimmer switch just doesn't feel like it would be as satisfying to me... Wondering if any of the great minds here have thought/could think of other more tactile ways to control the pressure manually throughout the shot?
> Cheers,
> 
> Yos
> 
> PS- Can't wait to share what I'm doing to my Gaggia Classic Pro with all of you soon !


 1: Yes
2: see the imgur link here (proof of concept)

https://www.coffeeforums.co.uk/topic/19103-gaggia-dimmer-switch-low-pressure-pour/page/5/?tab=comments&do=embed&comment=739856&embedComment=739856&embedDo=findComment#comment-739856

3. You could try to create a preinfusion switch if you wanted to that has a different circuit to reduce power to the motor, and then flipping it would bypass/short it as usual. But honestly, it's more fun with the dummer knob haha.



Agentb said:


> I'm interested to see how it all looks in the end 😎
> 
> Flow measurement with a shower-screen on or off, and if on / what make?
> 
> I'm assuming the OPV mod is done?


 With an IMS screen and brass shower holder. I forgot that's an important thing to mention . And yes, OPV modded at 9bar



Michael87 said:


> So I've hooked up the dimmer
> 
> AC 2000W Motor Speed PWM Controller Control Voltage Regulator Dimmer 110-220V
> 
> And it doesn't seem to be going low enough to have a noticeable effect on pressure. There is a variable dial, but I've just pulled 8 shots with it turned anywhere from 0 (far anticlockwise) up to 25 full rotations (in clockwise direction) with no significant difference in min pressure after moving the main control.
> 
> In the far anticlockwise you can hear the pump load dropping (which is nice and quiet) but still manages to attain around 9 bars measured with an in line pressure gauge between pump and OPV.
> 
> I'm wondering how this can be fixed.
> 
> I have an ivensys cp4/sp pump which might be the reason I'm getting different results. This is rated for 70W so maybe I need a lower power dimmer?


 Did you try the other terminals? If you have a multimeter, i'd check with that as well.


----------



## Olek

The pressure created by the pump is accumulating the dimmer allows a slower rise that is all.

I did not find much advantage in trying to make a pre moistering with low pressure, in fact this is happening in normal functioning I presume, just faster .

The pressure from the pump is may be 9bar but I suppose it is as show a gauge it raise progressively ,may be because only small amount of water is put under pressure at each vibe, and the circuitry do not hold pressure until 9 bar is attained, only the coffe in the filter is restraining the water flow and allow pressure to rise.

Regards


----------



## Yosuf

Thanks @handonam ! - I saw those videos, but they are just videos of shots (i.e. they dont show the actual dimmer switch, what it looks like being manipulated etc.) thats what I was after ! I would figure that everyone would be eager to show off such a cool feature ! Can't wait to see if this will work for me... !

Until then, I am flipping on the steam wand before brewing (valve isn't opened, just turning the button on) -- and once it lights up, I flip on the Brew button for a few seconds, after which I switch off the steam button then let it extract.... If that's the correct way to do the steam wand hacky pre-infusion thing then great (it does seem to have had a slight improvement on my previously messy pucks...) then again, knowing me I may be messing that up too ! 
Cheers,
y.


----------



## Olek

Michael87 said:


> So I've hooked up the dimmer
> 
> AC 2000W Motor Speed PWM Controller Control Voltage Regulator Dimmer 110-220V
> 
> And it doesn't seem to be going low enough to have a noticeable effect on pressure. There is a variable dial, but I've just pulled 8 shots with it turned anywhere from 0 (far anticlockwise) up to 25 full rotations (in clockwise direction) with no significant difference in min pressure after moving the main control.
> 
> In the far anticlockwise you can hear the pump load dropping (which is nice and quiet) but still manages to attain around 9 bars measured with an in line pressure gauge between pump and OPV.
> 
> I'm wondering how this can be fixed.
> 
> I have an ivensys cp4/sp pump which might be the reason I'm getting different results. This is rated for 70W so maybe I need a lower power dimmer?


 Have a look there : http://espresso-for-geeks.kalaf.net/features/pressure-profiling/

I had to add a strong resistance parallel on the dimmer to have my pump more responsive. I find the information on here I guess, but sorry no link I can think of.

Before that the pump (Ulka) did make a bad noise at slow regime.

When testing with a gauge I could have 2 bar for quite some time, but the pressure keep rising anywyay

the resistor lower the resistance the dimmer have to work with. I can have a look tomorrow on the setup


----------



## Michael87

handonam said:


> 1: Yes
> 2: see the imgur link here (proof of concept)
> 
> https://www.coffeeforums.co.uk/topic/19103-gaggia-dimmer-switch-low-pressure-pour/page/5/?tab=comments&do=embed&comment=739856&embedComment=739856&embedDo=findComment#comment-739856
> 
> Did you try the other terminals? If you have a multimeter, i'd check with that as well.


 I connected both original pump wires to the in terminals and then the out terminals to the pump. Do you think I could have the terminals the wrong way around? I assumed it wouldn't make a difference (Eg swap in 1 and in 2?)


----------



## Olek

I remind why I prefer to have max pressure at the start , it send the fines at the bottom of the filter and the extraction is slower, with more crema.


----------



## Michael87

Olek said:


> The pressure created by the pump is accumulating the dimmer allows a slower rise that is all.
> 
> I did not find much advantage in trying to make a pre moistering with low pressure, in fact this is happening in normal functioning I presume, just faster .
> 
> The pressure from the pump is may be 9bar but I suppose it is as show a gauge it raise progressively ,may be because only small amount of water is put under pressure at each vibe, and the circuitry do not hold pressure until 9 bar is attained, only the coffe in the filter is restraining the water flow and allow pressure to rise.
> 
> Regards


 That makes sense thank you, I've tested some more this morning and that's my experience. Slower ramp but still always getting to 9 bar.

I imagine the vibration pump is just pushing less water through per cycle, but then when the outlet pressure rises, it is still able to continue pushing until the OPV activates.

To achieve a lower max pressure I guess the pump needs to start stalling (voltage too low for electromagnet to be able to move the piston against the outlet pressure).

I've ordered a 15-120W dimmer switch to experiment and see if I can make this happen on that.


----------



## Michael87

A short update- I've now fitted a simple variable resistor dimmer (link) that clicks off. It seems to work well, although my OPV is a bit knackered so I can't tell the range yet. The click off allows me to preinfuse (turn pump off without de-energising solenoid and ruining pick), and I seem to have a decent range of pump power from the sound it is making. Will try and make a video tomorrow


----------



## Michael87

All fitted, preinfusion works perfectly, but I only have ~2bar control over pressure from around 7 to 9 bars.

Still looking for a dimmer that gives me an off switch plus broad pressure control from 1-10bars.


----------



## Rob1

Michael87 said:


> All fitted, preinfusion works perfectly, but I only have ~2bar control over pressure from around 7 to 9 bars.
> 
> Still looking for a dimmer that gives me an off switch plus broad pressure control from 1-10bars.


 I was looking into a dimmer mod for the Expobar long ago before the flow profiling stuff came out for E61s. The conclusion I came to was an arduino with MOSFET and bridge rectifier would provide the best control. A dimmer just alters the power draw and below a certain point the pump will stop working meaning you only get a very limited amount of control. At least these were my conclusions. In practice things might be different, The bianca came out and I just decided to wait until I could get hold of the paddle or something similar so I never gave it any more thought.


----------



## TomHughes

This is probably a really stupid question, but I am currently removing the dimmer switches from our house (partly because I can't seem to find dimmable light bulbs). 
Could I just wire one of these in to the live to the pump?

I think it's rated from something like 10-100w.


----------



## Michael87

After lots of tinkering, I think I've settled on a nice set-up. It's a super cheap 15-60W dimmer switch that clicks off, plus a 3000 Ohm power resistor (rated 50W). The dimmer is connected between the live (from the plug) and the pump, and the resistor is connected in parallel with the pump. Done using 6mm spade connectors and piggyback connectors, plus 14AWG wire. You'll need a crimper for the spade connectors, and a soldering iron for this dimmer.

Video shows complete control of pressure from 0 to 9 bars.

Sorry about the music, the wife and I were talking nonsense over and I don't want that in the public domain!


----------



## islandlad

Out of curiosity, has anyone managed to house the voltage regulator (the one below) in a readily available enclosure?


----------



## handonam

islandlad said:


> Out of curiosity, has anyone managed to house the voltage regulator (the one below) in a readily available enclosure?
> 
> 
> View attachment 41261


 I've been too lazy, lol.

I will probably drill into my machine though while I'm already in there to drill the fitted gauge


----------



## GrahamS

TomHughes said:


> This is probably a really stupid question, but I am currently removing the dimmer switches from our house (partly because I can't seem to find dimmable light bulbs).
> Could I just wire one of these in to the live to the pump?
> 
> I think it's rated from something like 10-100w.


 yes is the short answer - the long answer is you MAY need this circuit if the dimmer doesn't give much control.


----------



## GrahamS

handonam said:


> I've been too lazy, lol.
> 
> I will probably drill into my machine though while I'm already in there to drill the fitted gauge


 my temporary install is in a plastic bag. one day i will put a cable tie around the bag to make it safer.

I've just looked back in this thread. temporary as of May 2018........


----------



## DRAXXMENVONE

Hi Team! I'm considering doing the dimmer mod on my old Isomac Zaffiro. It has the Ulka EK2 pump so would swap that out. Were there any definitive recommendations for pumps and dimers that can be used when replacing an Ulka? I'm going to attempt to make some kind of 3D printed paddle too! The Zaffiro has a boiler pressure gauge which I'm sure is pretty inaccurate but it's just something I'd like to play with. I'd considered an E61 pressure control kit but then I'd lose my group thermometer.


----------



## minerek

guys, i have a question about mod with dimmer. i need to install this one:








where i can connect this resistor?
Can i install switch to this dimmer? after turning on, I would have a pressure of 3 bar, after turning off it returns to 9 bar. What do you think about this? how to do it?


----------



## Michael87

I used an Invensys CP4/SP pump and a 15-60W light switch dimmer with resistor in parallel to the pump as GrahamS shows. It's been working well and giving me 0.5 - 10 bar pressure control (measured between pump and OPV) nicely for a while now.


----------



## minerek

resistor between dimmer and pump? no matter which side?


----------



## GrahamS

minerek said:


> resistor between dimmer and pump? no matter which side?


 lookon the previous page. I put the circuit up. the resistor is in parallel with the pump so the entire load draws enough current, otherwise the noise filtering caps in the switch conduct all the time


----------



## Edmogeor

mcrmfc said:


> Nice will be interesting to see how that one behaves!
> 
> Take 3 for me is going to be a variation on a theme of motor speed controllers:
> 
> 220V 1500W Modulation AC Motor Speed Control Switch Governor White https://www.amazon.co.uk/dp/B00LXA6HY4/ref=cm_sw_r_cp_apa_TBbwzb4VP5W9J
> 
> Don't hold out great hope...


 Hi all. For anyone looking for this version for the speed controller for the Invensys pump (mentioned earlier in the thread) I found an identical one on amazon.de (out of stock on UK Amazon). Hasn't arrived yet but looks promising! Hoping to find space for it inside the Gaggia (perhaps undeneath the steam control?) For a clean install. https://www.amazon.de/-/en/Aexit-Modulation-Controller-Switch-Governor/dp/B07L3DVGP9

@mcrmfc Any problems since your original post a few years ago?


----------



## jpd99

Joy - opened it up, expecting to find an Ulka pump and there it was... an Invensys CP3A. No excuse for not fitting a dimmer now... damn...


----------



## Edmogeor

After some trial and error I have the dimmer mod working 100% from 0-9bar. I was having some issues at first (pump would sometimes give me full control but other times it would start at 2 bar on the lowest setting) but then adding an 800ohm 25w resistor in parallel with the invensys cp3a pump made it much more consistent (not noticing any drop outs when the heaters turn on with PID). Mounted inside the case(there's a nice bit of space just below the switch bank).

Important to note that the way these wire wound resistors work means they convert electrical energy to heat, hense the aluminium body. Mine was getting noticeably hot. I ordered some double sided heat tape (commonly used for mounting heatsinks etc.) And stuck the resistor to the metal body of the machine. I assume this will help with resistor longevity and reduces the risk of it melting any nearby wires.

For those wondering why they can increase pressure but not reduce once it's built up - likely due to using a pressurised portafilter basket.

For any with a Invensys pump the combination of a 800ohm resistor in parallel with the pump and this motor controller (https://www.amazon.de/-/en/Aexit-Modulation-Controller-Switch-Governor/dp/B07L3DVGP9) is working great for me so far.

While replacing the pump I also added a Quickmill pL0800PU Pulsor to the pump to reduce the volume of the machine - worked wonders or not sure if this has an effect on the setup atall.

here's an image of my machine all put back together, I have to say it's very convenient having the pressure control next to the switches on the front of the machine, can give inside picks if wanted:


----------



## Edmogeor

Update: the heat transfer tape doesn't seem to hold up too well. Going to try some thermal epoxy to glue to the case


----------



## Rebel

Does this mod flat out not work with the Ulka pump? I know that was the thought in 2014 but it seems some have had success.


----------



## MrShades

Rebel said:


> Does this mod flat out not work with the Ulka pump? I know that was the thought in 2014 but it seems some have had success.


 You'll need a large power resistor in parallel with the pump - and then it should be ok


----------



## Edmogeor

Edmogeor said:


> After some trial and error I have the dimmer mod working 100% from 0-9bar. I was having some issues at first (pump would sometimes give me full control but other times it would start at 2 bar on the lowest setting) but then adding an 800ohm 25w resistor in parallel with the invensys cp3a pump made it much more consistent (not noticing any drop outs when the heaters turn on with PID). Mounted inside the case(there's a nice bit of space just below the switch bank).
> 
> Important to note that the way these wire wound resistors work means they convert electrical energy to heat, hense the aluminium body. Mine was getting noticeably hot. I ordered some double sided heat tape (commonly used for mounting heatsinks etc.) And stuck the resistor to the metal body of the machine. I assume this will help with resistor longevity and reduces the risk of it melting any nearby wires.
> 
> For those wondering why they can increase pressure but not reduce once it's built up - likely due to using a pressurised portafilter basket.
> 
> For any with a Invensys pump the combination of a 800ohm resistor in parallel with the pump and this motor controller (https://www.amazon.de/-/en/Aexit-Modulation-Controller-Switch-Governor/dp/B07L3DVGP9) is working great for me so far.
> 
> While replacing the pump I also added a Quickmill pL0800PU Pulsor to the pump to reduce the volume of the machine - worked wonders or not sure if this has an effect on the setup atall.
> 
> here's an image of my machine all put back together, I have to say it's very convenient having the pressure control next to the switches on the front of the machine, can give inside picks if wanted:


 Found the resistor to get very hot - my mistake doing some maths it needs to be atleast 60.5 watts in my setup - upgrading to one of the 100w 800ohm resistors


----------



## Rebel

Edmogeor said:


> Found the resistor to get very hot - my mistake doing some maths it needs to be atleast 60.5 watts in my setup - upgrading to one of the 100w 800ohm resistors


 Is the 100w 800ohm resistor what I want for an Ulka pump running 120v/41w? Go with a 25w 800ohm resistor? Or something else? I want to add pressure control but don't want to fry my machine!


----------



## Edmogeor

Rebel said:


> Is the 100w 800ohm resistor what I want for an Ulka pump running 120v/41w? Go with a 25w 800ohm resistor? Or something else? I want to add pressure control but don't want to fry my machine!


 You want a 25w 3300 ohm resistor for the Ulka. Go back in the thread there's good info on that and the wiring.


----------



## Rebel

Edmogeor said:


> You want a 25w 3300 ohm resistor for the Ulka. Go back in the thread there's good info on that and the wiring.


 I read that (Page 6) but that was for 240V. Does the same resistor work for machines running on 120V?


----------



## SupraMan

> On 15/06/2020 at 21:02, Michael87 said:
> 
> After lots of tinkering, I think I've settled on a nice set-up. It's a super cheap 15-60W dimmer switch that clicks off, plus a 3000 Ohm power resistor (rated 50W). The dimmer is connected between the live (from the plug) and the pump, and the resistor is connected in parallel with the pump. Done using 6mm spade connectors and piggyback connectors, plus 14AWG wire. You'll need a crimper for the spade connectors, and a soldering iron for this dimmer.
> 
> Video shows complete control of pressure from 0 to 9 bars.
> 
> Sorry about the music, the wife and I were talking nonsense over and I don't want that in the public domain!


 Michael,
I have the resistor you recommended and a light dimmer from a switch in our house.
Any chance you could provide a quick picture of how the resistor is wired in?

I presume the dimmer goes between the brew switch and the pump? That is a red wire on mine I think.
The other connector is two black wires, is this the neutral?


----------



## BallisticNick

Has anyone tested the pumps that are used in the DE1? on closer inspection as to how the decent does preassure profilling, it seems similar to what we are doing on here (apart from it having two pumps instead of one).

Just wondering as the pump isn't much more expensive than the invensys but is still being manufactured, so if this pump works, it would be great to say to use this pump instead of the invensys, which is only going to get harder and harder to get ahold of.

I may get it myself, but I will need some help from you guys as to how to wire it up to a dimmer.

Here's the link to the pump:

https://decentespresso.com/parts?filter=DE-SOLPUMP220DV1-73301


----------



## Havald

BallisticNick said:


> Has anyone tested the pumps that are used in the DE1? on closer inspection as to how the decent does preassure profilling, it seems similar to what we are doing on here (apart from it having two pumps instead of one).


 I'm pretty sure Decent does not use phase control, they detect zero-crossings and turn on power for complete positive half-waves.

The pump may still work better than the Ulkas, just know that it's not guaranteed.


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## hackertom

Hello guys this pump is ok for preinfusion low pressure? I want to change with ULKA...

Gaggia Classic change pump



http://imgur.com/QyjYDN6


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## rontheotherhand

finally got round to trying this mod. I'm a but stuck however and was hoping someone can give me a few pointers.

I've got a circa 2005 machine.

I'm using a new "Invensys" CP3A pump that I have swapped in for my old Ulka pump and paired it with a 2000w dimmer switch. I'm using a portafilter + presure combo as I have a "preheat mod" - basically a load off copper pipe around my boiler so getting a gauge into the case is difficult.

anyway, its all hooked up but I'm getting a drop of about 0.5 - 1.00 bar and am just wondering if I need a different dimmer switch or have made an error?

https://ibb.co/x3FZWSk
https://ibb.co/FVvRBWr


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## newdent

GrahamS said:


> NOOOOO! 25W !!!!
> 
> 240/3300 = 7mA
> 
> 0.007 x 0.007 x 3300 (I2R) = 16W
> 
> a 0.25 would disappear in a puff of smoke
> 
> https://www.ebay.co.uk/itm/232738494106


 I'm doing this mod shortly so thank you for all the information on this thread.

I didn't want to go and buy components without a small amount of understanding. The dimmer I'm looking at quotes 50 to 220VAC, 2000w, so if there are problems at the low end, presumably 50VAC is not enough for the ulka pump to control well? Some of the dimmers, (such as the attached photo), show a component (presumably a variable resistor) for adjusting the lowest voltage that can be output. I'm going to try adjusting this before investing in an additional load resistor as I pre-infuse at 3 bar, which is quite high anyway.

I'm going for this dimmer, even though it's a bit pricier (£7.19 at the mo) so that I can mount the control board as far away from the boiler as possible; https://www.amazon.co.uk/gp/product/B07PHSH3QX

Regarding the quoted text, If I do end up needing a dummy load resistor to get it working at the lower end, could someone assist in calculating this please? Why did you go for a 3300 ohm resistor, just what you happened to have lying around?

Lastly, has anyone used this particular dimmer with success with the standard 48W Ulka pump (the same board with a fixed pot seems to be the most common one that comes up in the searches, it's he one pictured below)?

Thanks guys.


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## jtracy

Right, I managed to wire in my dimmer to the Ulka pump, but it has stopped it working completely no matter how I turn the dimmer!!

pretty sure I've wired it ij the right place (the red wire that goes from the switch to the pump.

could it be that I just need the invensys pump or a resistor or do I need a different dimmer. Current dimmer is for a light switch rated at 5-100W.


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## BikeShedd

So I fitted this today https://www.amazon.co.uk/gp/product/B075QFQN7S/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

and I'm waiting on a resister arriving tomorrow. My question is, where are you guys mounting them inside the case? I've just got mine hanging around in there. I got a shock off the case when I was testing it (I think from the circuit board touching the case, can't think of what else it could have been) I've used some insulation tape just now for a quick fix. I liked this dimmer as the knob is on a long wire that I can feed out the back and don't have to drill a hole. What's the thoughts?

I don't really want anymore shocks. That wasn't too fun.


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## 9bars

First post!

I have fitted this dimmer, with a 3.3 ohm 25W resistor in parallel. Pump is a 230V Ulka type.

It seems to be working okay, I can adjust it down to 3 bar or so. Checked with a multimeter the voltage gets down to around 10-15v.

However the issue I'm having is that the first 1/3 range of the dial does nothing. I can hear a slight humm. My guess is the pump stalls below a certain voltage. The issue is this makes adjustment a bit difficult.

Is this normal or should I be considering a different dimmer?


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## Calvus

Does it work with all vibration pump (e.g Lelit Elizabeth)?


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## Bhodgson

9bars said:


> First post!
> 
> I have fitted this dimmer, with a 3.3 ohm 25W resistor in parallel. Pump is a 230V Ulka type.
> 
> It seems to be working okay, I can adjust it down to 3 bar or so. Checked with a multimeter the voltage gets down to around 10-15v.
> 
> However the issue I'm having is that the first 1/3 range of the dial does nothing. I can hear a slight humm. My guess is the pump stalls below a certain voltage. The issue is this makes adjustment a bit difficult.
> 
> Is this normal or should I be considering a different dimmer?


But old I know, but I’ve been pondering this.
whatever doohickeys you wire in, you’re trying to do something that an ac motor can not do. AC gear starts destroying itself, when voltage drops too low.
now a DC motor, would work happily with your dimmer.
seems to me a conversion to a DC pump, would make more sense.

mind you. On the fly OPV adjustment, makes even more sense. how would be the problem.


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## Michael87

It must be your particular dimmer. I've got an ulka pump and can adjust it down to 1 bar


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## Bhodgson

Michael87 said:


> It must be your particular dimmer. I've got an ulka pump and can adjust it down to 1 bar


It really doesn’t matter. AC gear, however many gadgets you wire into it, destroys itself if you reduce the voltage. It’s simply not designed to work that way.
it is undoubtedly possible to design a AC unit, that could deal with variable voltage. but, the pumps used aren’t.
I know it’s a pain dealing with things like transformers, but DC, if you insist on using this method of pressure control, is the way to go. 12v 200psi dc pumps, cost around £25 up.


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## Quake94

Hello All, I have a machine with the Ulka EP5, 115VAC (US). After much deliberation I decided to add in a dimmer to regulate pump pressure.
I use Eureka Crono for grinding
So here is how my endeavour went:
- Before dimmer, I would get 17g in, ~32g out in 17 seconds (due to about 10-11 bars OPV spring, methinks, spring is the same as Gaggia's). No channeling/puck breaking apart. Taste was good, but I thought, well, at lower pressure (9bars and below) I should be able to go finer, lengthen the pull time == more flavorful coffee


I went out and got a Fan Speed control dimmer Eaton RFS5-A 5A 120VAC Fully variable. From a short research, apparently the Fan Speed control dimmer will start at 100% and decrease when going clockwise on the knob, while the regular dimmers do the opposite. I do not know what are other differences...
I wired it inline with the Ulka correctly

Initial testing resulted that I could vary the flow rate and could hear the modulation, albeit pump would stall/turn off somewhere after 50%, I played around with it, and adjusted the trim pot in the dimmer, which made the pump working range wider

However, even at full ON my flow rate seemed worse than without dimmer. I disconnected the dimmer, and realized my pump does not produce the same flow rate/pressure as before?
When pulling 18g in, I get ~21-24g yield in 26 seconds. Grind size is the same as pre-dimmer, and grinding coarser barely made any difference.
I thought maybe air got in the lines since I had to disconnect the flowmeter to get to connectors, I purged the system and I am pretty confident there is no air left.

Maybe someone with electrical experience can chime in, what type of dimmer is the most suitable? These are all solenoid pumps with electromagnet and a driving circuit.
Could I have weakened the pump by using the fan speed dimmer? I would imagine the pump either works at full capacity or not if it is damaged, but not in between.
I am curious what resistance do Ulka EP5 115VAC terminals measure?

Any pointers for troubleshooting are welcome
If I end up replacing pump, I would prefer to avoid burning the new one out...


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## Bhodgson

I refer you to post #178.
the mechanics, of the pump, will deal with it no problem. It’s the fact it’s an Alternating Current item that's giving problems.
however successful adding gubbins is, at making it seem to work. The motor is slowly destroying itself. 

variable frequency control unit would be your only way forward ( effectively switching on and off, the power, extremely quickly)


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## Quake94

Bhodgson said:


> I refer you to post #178.
> the mechanics, of the pump, will deal with it no problem. It’s the fact it’s an Alternating Current item that's giving problems.
> however successful adding gubbins is, at making it seem to work. The motor is slowly destroying itself.
> 
> variable frequency control unit would be your only way forward ( effectively switching on and off, the power, extremely quickly)


Naturally the best way for AC is a VFD (modulating supply line frequency), but that is cost and size prohibitive.
If I understand correctly, solenoid valves should not be run at over or under 10% rated voltage. So by introducing a dimmer, the windings start degrading.
Do you think that unavoidably all the AC solenoid pumps will eventually get shot if paired with dimmer?


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## Bhodgson

AC gear has a voltage range, written on it. In the case of the ULKA pump, it’s rated for only 230v. Which in reality means 220-240v. If you're in the states they are rated 120v, which means 110-130v. Anywhere outside those voltages, causing damage to the motor, and is introducing instability.

there is no cheap way to make an AC unit, variable voltage, I'm afraid.


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## Quake94

Bhodgson said:


> AC gear has a voltage range, written on it. In the case of the ULKA pump, it’s rated for only 230v. Which in reality means 220-240v. If you're in the states they are rated 120v, which means 110-130v. Anywhere outside those voltages, causing damage to the motor, and is introducing instability.
> 
> there is no cheap way to make an AC unit, variable voltage, I'm afraid.


Fair enough, I would urge @MrShades to revise original post and add a warning for any future tinkerers. I am genuinely curious how fellow modders have been doing with their dimmer setups.

I will be replacing the EP5 pump with EFX5, I think it is the top of the line Ulka pump (brass internals, F class, 2/1 duty cycle)
Next up, adding pressure gauge and a valve...


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## Bhodgson

After the PID, the gauge will be a breeze. Are you using the Shades housing, or are you drilling the case?


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## Quake94

Bhodgson said:


> After the PID, the gauge will be a breeze. Are you using the Shades housing, or are you drilling the case?


I have easy access to PID temperature controllers, SSR's, sensor and all kinds of control components through work, and might add it...
It is the second priority though, the temperature is quite stable since the last time I checked with a calibrated thermometer.
I am modding a non-Gaggia machine with a plastic enclosure. Most likely will put together control unit and install outside.
I have a knockout punch available from work as well...makes it all the easier 😉


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## Ranger777

I just added this dimmer to my GCP post 2019 build








I keep getting channeling in the to the left side mid way puck....always bitter and over extracted? I just read that these are a triac dimmer and will always have a electric pulse wave and this might explain how it's messing with the pressure causing it to channel ? My question is why haven't people been experiencing this and eveyone says they get perfect shots ? 

I should add I have also added the 3000ohm resistor in and controls all levels of dimm without cutting in and out of power


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## Bhodgson

Ranger777 said:


> I just added this dimmer to my GCP post 2019 build
> View attachment 69695
> 
> I keep getting channeling in the to the left side mid way puck....always bitter and over extracted? I just read that these are a triac dimmer and will always have a electric pulse wave and this might explain how it's messing with the pressure causing it to channel ? My question is why haven't people been experiencing this and eveyone says they get perfect shots ?
> 
> I should add I have also added the 3000ohm resistor in and controls all levels of dimm without cutting in and out of power


As you say messin with the voltage, on AC, causes problems, every time. 
whatever gubbins you add, the pump will simply not run consistently, if you reduce the voltage below 220 v in Europe or 120v in the states. 
Its the basic physics, of how AC voltage works, that causing the problem. And whilst we've got some really good tech, to try and hide this basic problem, it will always be there.

id happily spend over £100, per unit, on a proper DC solution. But, as yet, there isn’t one. unfortunately, nobody is going to design and make one, either. Because there simply aren’t enough people, with Classics, to make it a viable proposition.

I’ve even looked into a rotary pump, as a solution. But it’s expensive and needs plumbed into the mains water. Plus every one, I’ve found, is way too big to fit inside a classic, anyway.

it occurs to me. Messing with the pump, possibly, isn’t the right way, to go, anyway. Shouldn’t we be looking an adjustable OPV, system?


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## bbstrikesagain

Wow, as an electronic designer with a decent understanding of electronics, electrical machines, and mechanics, some of the misconceptions above are a bit staggering, so some observations, not just for Gaggia, not just for Classics, maybe deserving their own post, but anyway, (over) thought for the day:

A standard AC *leading edge* phase-delay triac/diac type dimmer WILL NOT harm the pump coil or the pump mechanics
The science is sound and lots of us use them all the time without issue
A great way to effectively modulate the pump over a wide range
The 50/60Hz vibration frequency is unchanged
The 50/60Hz output volume and pressure pulses are reduced in amplitude when dimmed

I wouldn't recommend risking any other type of dimmer, except perhaps a proper variac (variable transformer, bulky, expensive)
Modern dimmers for LED compatibility tend to default to *trailing edge* mode which could lead to inductive flyback voltages breaking down the coil insulation
Some sophisticated dimmers, _if operating in leading edge mode_, might be safe and may even have other advantages, but caveat emptor...

The *vibratory pump* is not a motor
Nothing moves in a constant direction, no spinning shaft or travel along rails
It cannot stall, since it only ever oscillates
It can be safely operated down to zero pressure/flow (by amplitude or leading edge modulation)
Running the pump dimmed means you can safely run it for longer than normal thermal limits (2 minutes ON, 1 minute OFF), e.g. when de-scaling

A dimmed vibratory pump is unlikely to cause channelling itself, but the pressure/flow profiling you apply with the dimmer might:
Reduce puck compression and choking risks by controlled pre-infusion
Allow you to grind finer, fine enough to increase channelling risk and place more demands on puck prep etc

Using a standard dimmer together with a PID some users, especially 120V users, might notice pressure and flow coming in waves timed with the PID control of the heaters...

This is a consequence of mains voltage dipping while the heaters are ON. The voltage dips have the same effect as briefly turning down the dimmer knob, during the heating time, delaying the leading edge phase and so throttling back the pump. The unwelcome dimmer response compounds the fact that the the dipped mains voltage would slightly reduce the pump amplitude even if the phase didn't also get delayed. 

In 220-240V cases the effect is certainly noticeable at mid range dimmer settings. In 110-120V I understand it can easily be as much as a several bars of modulation, which can't be much fun and would certainly annoy me. But either way, these heater related pressure and flow changes should be fairly inconsequential to the espresso, especially on the GCP with it's soft silicone high pressure hose and smaller (effective gicleur) orifice in the 3-way slugging any pressure change shocks at the group and in the puck.

In short, don't worry about it, or if you do, then maybe consider any of:

use a the dimmer only for pre-infusion, then just turn it up full to rely on an OPV setting for extract pressure
use a boost switch (or relay etc) to switch the heaters ON during the pump-ON time (risk of overheating extraction during long/slow pulls)
use an anti-boost switch (or relay etc) to switch the heaters OFF during the pump-ON time (risk of increased temperature droop during long/slow pulls)
investigate exotic dimmers in case one works?
wait for someone (me?) to design and build a leading-edge dimmer with its firing phase angle stabilised against input mains voltage variations, perhaps even with additional automatic supply voltage compensation phase when dimmed, a 3-wire dimmer with Phase IN, Phase Out and Neutral, rather than the usual 2-wire dimmer
The way systems like gaggiuino work, where phase control is mainly determined by a microprocessor (rather than a variable resistor tapped direct from mains voltage) means the pump should be less affected by heater induced voltage dips. Personally, if I had to live with 110V I think I'd design and build that custom dimmer I have in my head, or buy a lever machine, rather than give up on-the-fly manual profiling


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## grgz

bbstrikesagain said:


> *Using a standard dimmer together with a PID some users, especially 120V users, might notice pressure and flow coming in waves timed with the PID control of the heaters...
> 
> This is a consequence of mains voltage dipping while the heaters are ON. The voltage dips have the same effect as briefly turning down the dimmer knob, during the heating time, delaying the leading edge phase and so throttling back the pump. The unwelcome dimmer response compounds the fact that the the dipped mains voltage would slightly reduce the pump amplitude even if the phase didn't also get delayed.
> 
> In 220-240V cases the effect is certainly noticeable at mid range dimmer settings. In 110-120V I understand it can easily be as much as a several bars of modulation, which can't be much fun and would certainly annoy me. But either way, these heater related pressure and flow changes should be fairly inconsequential to the espresso, especially on the GCP with it's soft silicone high pressure hose and smaller (effective gicleur) orifice in the 3-way slugging any pressure change shocks at the group and in the puck.*
> 
> In short, don't worry about it, or if you do, then maybe consider any of:
> 
> use a the dimmer only for pre-infusion, then just turn it up full to rely on an OPV setting for extract pressure
> use a boost switch (or relay etc) to switch the heaters ON during the pump-ON time (risk of overheating extraction during long/slow pulls)
> use an anti-boost switch (or relay etc) to switch the heaters OFF during the pump-ON time (risk of increased temperature droop during long/slow pulls)
> investigate exotic dimmers in case one works?
> wait for someone (me?) to design and build a leading-edge dimmer with its firing phase angle stabilised against input mains voltage variations, perhaps even with additional automatic supply voltage compensation phase when dimmed, a 3-wire dimmer with Phase IN, Phase Out and Neutral, rather than the usual 2-wire dimmer
> The way systems like gaggiuino work, where phase control is mainly determined by a microprocessor (rather than a variable resistor tapped direct from mains voltage) means the pump should be less affected by heater induced voltage dips. Personally, if I had to live with 110V I think I'd design and build that custom dimmer I have in my head, or buy a lever machine, rather than give up on-the-fly manual profiling


Exactly this is the case, when the PID kicks in it's like you decrease pressure with the dimmer. Unless you design your special dimmer switch i thought about giving AC to the pump only from a separate source in order to put the PID out of the equation. Maybe i will give it a try.


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