# Silvia flow control mod



## Doram (Oct 12, 2012)

Saw this on reddit and thought it was cool enough to share:

https://www.coffeeforums.co.uk/index.php?app=core&module=system&controller=embed&url=https://www.reddit.com/r/espresso/comments/m6ogfv/rancilio_silvia_pressure_control/


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## phario (May 7, 2017)

Very cool and interesting though most people just do a dimmer mod to adjust pressure!


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## Rob1 (Apr 9, 2015)

It's better than a dimmer but why is everything outside the machine. Could easily be inside, just needs to cut a hole for the nob and mount the pressure gauge to the front same method....from looking at internal pics there looks to be room for it.


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## phario (May 7, 2017)

Rob1 said:


> It's better than a dimmer but why is everything outside the machine. Could easily be inside, just needs to cut a hole for the nob and mount the pressure gauge to the front same method....from looking at internal pics there looks to be room for it.


 Out of curiosity, why is this better than a dimmer?


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## Rob1 (Apr 9, 2015)

phario said:


> Out of curiosity, why is this better than a dimmer?


 I guess things may have changed a bit from when I was looking into it but from what I read a dimmer wouldn't give you full range control i.e- 0-9 bar and adjustments wouldn't be very precise with a lot of the dimmers out there, there was talk of pumps not working below 4 bar etc, or at least becoming unpredictable and fluttering below that. There are too many types of 'dimmer' available to really be specific though, e.g. a rheostat dimmer will lose power to heat. Solid state dimmers are probably most common now. Sine wave dimmers might be best for controlling pressure, frequency control will alter flow to equal pressure...

Or you can just use a valve to control flow and have full, fine control from 0-9 bar. If you if you get the right type of dimmer you might be able to get predictable and fine control across the 0-9 bar range or whatever your pump/opv is limited to.


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## phario (May 7, 2017)

Rob1 said:


> I guess things may have changed a bit from when I was looking into it but from what I read a dimmer wouldn't give you full range control i.e- 0-9 bar and adjustments wouldn't be very precise with a lot of the dimmers out there, there was talk of pumps not working below 4 bar etc, or at least becoming unpredictable and fluttering below that. There are too many types of 'dimmer' available to really be specific though, e.g. a rheostat dimmer will lose power to heat. Solid state dimmers are probably most common now. Sine wave dimmers might be best for controlling pressure, frequency control will alter flow to equal pressure...
> 
> Or you can just use a valve to control flow and have full, fine control from 0-9 bar. If you if you get the right type of dimmer you might be able to get predictable and fine control across the 0-9 bar range or whatever your pump/opv is limited to.


 I guess it boils down to the fact that mechanical control is sometimes easier than electrical control.

Regarding the use of dimmers, my understanding is that cheap dimmers can be effectively implemented with the standard vibration pumps and the only tricky business is that you may need to use a resistor. See comments by @Olek and @GrahamS regarding the 3300 Ohm resistor.


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## AlbertoG (Jul 25, 2020)

Did anybody implement this? I am thinking of having a fo, so could do with any advice on pieces, expectation for performance, etc.

Thanks!


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