# Gene Cafe dimmer mod tips please



## hullcity

I've just done the dimmer mod for my gene and all appears to work well on a dry run.

I'd appreciate any tips you mod users have on using the dimmer during the roast. Any profiles for different bean types, drying phases, slowing the heating ramp etc etc? Do you aim for a certain power (watts) during heating to eliminate the effect of voltage fluctuations or just switch the dimmer on once the desired temp is reached?

Any info will be helpful. Thanks in advance.


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## froggystyle

Wheres the mouse, hes your man!


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## froggystyle

Where did you source all the parts from?

Been thinking i need to do this to mine but not sure where to get the bits from, more importantly the strips of metal?


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## hullcity

froggystyle said:


> Where did you source all the parts from?
> 
> Been thinking i need to do this to mine but not sure where to get the bits from, more importantly the strips of metal?


I got the dimmer from these guys via fleabay: http://www.kibuck.com/1800w-triac-dimmer-module.html. This unit was mentioned in a thread talking about the dimmer mod (can't remember who, probably Davecuk) and has a high enough power rating to handle the gene, so no need to add an extra heatsink.

The other bits came from my local DIY shop. I just got a switch and put it together with the dimmer module in a junction box. Looks a bit naff but hopefully should hold up ok.


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## froggystyle

Yeah you see, that's my worry that it looks a bit bodged when your done, maybe ill go down the posh alli dimmer...

Have you got a photo of the heatsink?


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## 4085

As far as I can remember, I used to start the roast off as normal (presuming your voltage is ok), then when first crack is reached, flick it over. You then need to set your mulitplug over to show the wattage not the voltage. I think typically the watts would be around the 1150 mark. The point of this is to control or stretch out second crack, so I used to reduce the wattage down to around 800 and play it by ear!!


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## hullcity

froggystyle said:


> Have you got a photo of the heatsink?


There you go, just for you Froggy







. Dimmer module is on the left. I had trouble finding a suitable box and just went with what I could find. Didn't cost much though, about 20 euros for the entire mod.


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## hullcity

dfk41 said:


> As far as I can remember, I used to start the roast off as normal (presuming your voltage is ok), then when first crack is reached, flick it over. You then need to set your mulitplug over to show the wattage not the voltage. I think typically the watts would be around the 1150 mark. The point of this is to control or stretch out second crack, so I used to reduce the wattage down to around 800 and play it by ear!!


Thanks dfk. So you didn't use the dimmer ever to control the rate of rise? I can have rather variable line voltage so was thinking of using the dimmer to control heating by using a set wattage to try to get better consistency between roasts. I'll definitely use it to stretch out the time between first and second crack.


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## 4085

What is your voltage, because if it is low, then unless you already have the 230 v element, you can get one and slot it in and that should take care of that. the Gene is very voltage sensitive. I have the 240 v model and if the voltage is below 237 I do not bother.


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## froggystyle

I would think you would only need to control the roast after a certain temp, maybe first crack?


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## hullcity

dfk41 said:


> What is your voltage, because if it is low, then unless you already have the 230 v element, you can get one and slot it in and that should take care of that. the Gene is very voltage sensitive. I have the 240 v model and if the voltage is below 237 I do not bother.


I have the 230V model but I live in France. My line voltage is usually around 235 to 238 but can go up as high as 245.


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## hullcity

froggystyle said:


> I would think you would only need to control the roast after a certain temp, maybe first crack?


Yeah, for most beans I think you're right. But for Brazilians and soft beans it might be beneficial to heat up a touch slower? My gene seems to get up to temp pretty quick and I'm concerned it may be a bit too aggressive for some beans.


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## froggystyle

I thought the idea was to get it up to the set temp, then use the dimmer to control the issue of the heater switching on/off all the time?

Need Dave or Mouse or shares some pearls of wisdom i guess.


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## 4085

Written by Davec

I start my roasts with the Gene set to 240C and the switch in the DIR position, so that the dimmer is not being used and for at least the first 5 minutes and possibly up to 1st crack, I won't be using the dimmer module.

As soon as I want to control the temperature or slow the ramp, I switch to DIM and start using the dimmer (which I leave initially in the fully bright position). I find that depending on the ambient temperature and the temperature I want to maintain my roast at&#8230;.around 1050 to 1100 watts in winter (possibly 1000W in summer), is enough to maintain the temperature without the element switching on and off. My Gene temperature control knob is now simply a safety or limiter on the maximum temperature the roast can achieve.

Note: don't set the genes own temperature control too close to the desired temperature as if the Gene reaches it, it will switch off the element and drop nearly 3/4C, something we want to avoid (This is why I use 240C).

So if your voltage is good, you can control part of the ramp up and certainly have a controlled drying stage if you want to&#8230;.for beans which are reaching 1st a little rapidly again you can temper this. At and beyond 1st crack you can pretty much set whatever profile you desire. The temperature gradient within the drum when under dimmer control will be at the absolute minimum it can be.

At the end of the roast, I switch back to direct to take the dimmer out of the circuit, because otherwise there will be a small voltage (50V) across the dimmer during the cooling cycle and as long as the Gene is physically plugged in..with no load on the Dimmer (dimmer requires a 200W minimum load), I am not sure if this will have any effect on the triac within the dimmer, it's unlikely but there is no point in taking chances. The other reason for having the two way switch, is that there is a 30W power loss within the dimmer, but of course NO power loss with the switch in "DIRECT" mode

Initial results are very encouraging, roast quality is great, roasts are visually more even, especially on beans which tend to be a little uneven anyway. Careful inspection will show a significant reduction (or absence) of Divots, Tipping or scorching. Interestingly roasts can actually be heard entering second crack, but the bean does not seem as dark as it would usually be when this happens, indicating the possibility or a more even roast throughout the internal structure of the bean.

Source: http://coffeetimex.wikidot.com/gene-cafe-dimmer-control-mod-stage-1


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## froggystyle

Thats what i thought..

Get it up to temp and surf...

Only problem is, how do you know your at temp, would you set it to your desired temp say 230c then when it hits this flick the switch and turn the gene temp up and surf using the dimmer?


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## 4085

Well, if you think about it, if your voltage is 240 when you roast, even in summer, for me, it takes approximately 11 to 12 minutes to reach my desired temp presuming it is no higher than 234 or so. that corresponds to approximately first crack, hence my posting about not switching to dimmer until then. I just try to control between first and second, although I have to say my new Gene behaves totally differently to my old one!


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## DavecUK

Yes and with a 230V heating element (that passage was for use with a 240V element), I would of course leave the dimmer enabled all the time, unless roasting in the middle of winter at 222V or something, in which case I might switch out the dimmer (or used to when I had my roaster). I strongly recommend the 230V element with this mod for best performance, as it allows for full control and overboosting the system in cold weather.

It is indeed the same module I have in my garage and one I would have pointed people to as an alternative. The only thing to be careful here is:

1. I used the Varilight dimmer (detailed in the wiki), it costs2.5 to 3x the price of the one you're using. I checked with varilight and they were using it in a project for a 1500W custom dimmer, but were adding a heatsink. They confirmed it should handle the uprated load with an additional heatsink

2. It's stuck in an unventilated patress box and when testing that particular unit at a load of 1200W I did find the heatsink became pretty hot and would strongly recommend adding an addition heat sink to it. Don't remove the original, but try and add to the original heat sink

3. I don't know how much power the module looses, but you might want to measure this, so that you are comparing apples with apples when you swap notes with other people, as small amounts of power can make a large differences. A friend and I did comparisons, dim direct vs no dimmer, with a known load across the dimmer (e.g. light bulbs etc..). I think it was around 30-40WW. Are they all the same...I don't know. Of course you have to try and ensure you do this test wityh no voltage fluctuations, mid afternoon is usually best.

The only slight downside of the dimmer I used is the fact that it's push on off and if the knob (project knob I bought) is not on far enough (and some of the knobs had variance), it's possible to "push off" the dimmer and then think it has failed. I know this because a friend of mine was always calling me thiking his dimmer had failed....when in fact he had simply switched it off by accident.

Usage of the dimmer mod can be succinctly described with.

1. Use approx 1120 to 1180W (varying the range in extreme heat or cold) to obtain the ramp rate you want for a particular bean.

2. Use the dimmer to obtain the final heat you want, by balancing the power (set Genes on temp to 245, way out of the way, so it wont switch on and off), you may or may not be hearing 1st crack at this time

3. As the roast comes near the end and first crack is ending...decide the final power you want to coast along to end of roast....e.g. steady temp or slight rising temp

After tasting use the notes to either recreate the roast exactly, or experimentally vary it to improve the roast. As the Gene is roasting on power (because you note down the powers used), for the same bean the only variable left is environmental temperature. If that's pretty similar, the roasts are reproducible. More so than any other home roaster (and many commercial roasters). it's also a profile that can be perfectly shared with others using the same mod (caveat: see 3 above). I have been constantly amazed that more manufacturers don't move to power based roasting control.

I do not overstate the case here when I say the Gene with the mod and 230V element (probably), becomes one of the most controllable home roasters available. it has speed of control and the ability to speed up and slow down a roast that others don't have. For the money...it simply can't be beat. No one I know has had a problem with a full modded Gene, some of which have been used 2 or 3 times every week for nearly 7 years.

*Also check with Bella Barista if you have a new one or one in warranty, as I am pretty sure that if you do the mod, you won't invalidate you're warranty...unless it was something you broke when doing the mod, or something as a direct result of not doing the mod correctly e.g. re-sealing the heater box.*


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## hullcity

dfk41 said:


> Well, if you think about it, if your voltage is 240 when you roast, even in summer, for me, it takes approximately 11 to 12 minutes to reach my desired temp presuming it is no higher than 234 or so. that corresponds to approximately first crack, hence my posting about not switching to dimmer until then. I just try to control between first and second, although I have to say my new Gene behaves totally differently to my old one!


My gene gets from 20C to 250C in 6 min when empty. With a 250g load, at around 240V, it takes around 8 min to get to 230C and 8:30 to get to 235C. First crack is usually at somewhere between 11:30 and 12:30 min, depending on the bean. That's all with no preheat. So without the mod I usually had 3 to 4 min of element-switching before the start of first crack.


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## hullcity

Thanks Dave for your very detailed and informative reply.

I will have a look at how much power the module loses when in use. Since it's rated at 1800W is it really necessary to add another heatsink?


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## hullcity

OK, I've just run the gene with no beans and find that the dimmer (full on) drops the power by 7-10W when switching it in and out of the circuit. That's at a steady 238V over the course of heating from 20 to 220C, 10 samples.

By the way, the gene was using between 1370 and 1390W during the test (dimmer out of circuit).


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## DavecUK

hullcity said:


> Thanks Dave for your very detailed and informative reply.
> 
> I will have a look at how much power the module loses when in use. Since it's rated at 1800W is it really necessary to add another heatsink?


I think it's a good idea...but its up to you. I'm sure the ratings given on ebay are accurate:rolleyes:


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