# DIY PID Mods



## Prata (Aug 16, 2012)

Has anyone done a PID mod before? I'm interested in doing a mod to a second hand Gaggia classic that should be arriving soon. I know common advice is not to bother with it, since there's other ways to improve a cup much more drastically with better technique etc.

However for me this is all about the fun of it, so a kit is out of the question. I have a pretty good idea of how I want to control the temperature, with a Raspberry Pi or and Arduino as the PID controller, which I will program myself, and a solid state relay to control the boiler power. However I'm not really sure how to go about measuring temperature in the boiler. From what I've seen of the boiler so far it seems that the thermostat screws in through a small hole.

Am I right in saying that PID kits use a washer thermocouple on the thermostat screw outside of the boiler? Ideally I would have a thermocouple inside the boiler, or better yet one of these: https://www.adafruit.com/products/381 but having not looked at the boiler up close yet, I'm not sure it can be inserted without drilling a hole in the boiler and I don't want to do anything that risks losing boiler pressure.

Also the other exciting thing about this is that if I use the Raspberry Pi, I can use SSH to switch on the Gaggia over the internet, so that it's warmed up by the time I get home!

Let me know what you think!


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## cjbailey1 (Jan 17, 2011)

Have a look here - it's not a Classic, but a working DIY PID setup:

http://coffeeforums.co.uk/showthread.php?7016-Rancilio-Silvia-V3-with-Arduino-controller

Personally I would not want to drill the boiler and I've not seen anything that I'd want to put into a steam boiler for measuring temperatures so I would go with the external method still. The thread above (and several others) also talk about insulation.


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## palkie (Oct 8, 2012)

I am still deciding on whether to do an arduino PID. Checkout philipmc's progress here (I love the screen and the ability to have so many potential modification).... http://coffeegeek.com/forums/espresso/machinemods/557870?LastView=1349721605


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