I would like to learn how to put together a PID controller like the one in the link below. Can anyone tell me what I would need and how hard it would be? Would I be able to do it more economically that just purchasing one?

http://www.auberins.com/index.php?main_...ucts_id=48

You would need:
- A PID with relay output, and I would also want an auto-tune function
- A sensor capable of submersion
- a project box to mount the PID in
- a power cord
- a switch (the DPST is a good idea to be sure everything is off and safe)
- a surface-mount electrical socket for the kettle to plug into
- an SSR (solid state relay). 15 amps would be a good choice.
- wiring as needed, a strain relief for the power cord, socket for sensor possibly, etc.


The ground connections would be to a common lug inside the box

I suppose there are other ways to do it, but I think this would work, and it could be used to control many different systems (like a deep fryer, etc.)

Here is an Open Source PID controller kit folks are using to control coffee urns
for sous vide cooking and diy bio-hacking.
I am thinking about adding it to my Gaggia Evo -
it includes the Solid State Relay.
Assembly *is* required.

http://lowereastkitchen.com/wp/

Don't know your application exactly, but you might consider a $30 router speed controller like the one I use to control my La Peppina. Works very well, stable, easy to change temp and to turn off. No probes necessary. Just a good thermometer for initial calibration.

So if its for keeping a non-pressurized vessel at the same temperature (say 208f), it would work well, I think. If you try it and it doesn't do what you want, you'd still have a nice dimmer for speed control for other uses.

I would agree on a "PID" controller being a good choice. It is pretty amazing how cheap they have become on eBay these days. I can't comment on the quality of the ones that now make an Auber look "high end" by comparison.

I think the biggest challenges you will face come in tuning the controller, not in assembling it. You've typically got a relatively large heating element compared to the volume of water. Beyond that, if the amount of water in the kettle varies, the dynamics of the system will vary as well. PID controllers aren't magic; even the best auto-tune algorithms (which you probably aren't getting in an "eBay special") will have a hard time dealing with the very fast heating, relatively slow cooling, and changing mass of water, especially on a kettle that will boil water in a minute or so. I wouldn't be surprised if you end up with mainly a Proportional controller (with the Integral and Derivative parts turned off), or close to it.

Don't mean to be a party-pooper, but why would you want a PID kettle? The temperature precision that a PID controller provides is mitigated by the sum of the other factors involved in filter coffee brewing. PID makes sense for espresso, much less so for filter brewing.

I have a Japanese airpot 1.8 liter, I think, that keeps water at 208 reliably and accurately. You might want to look into one of those. I think it cost less than $100 (on sale), less than a PID and it dispenses the water with a two speed pump.

Nick wrote:Don't mean to be a party-pooper, but why would you want a PID kettle? The temperature precision that a PID controller provides is mitigated by the sum of the other factors involved in filter coffee brewing. PID makes sense for espresso, much less so for filter brewing.

I am using the Pino kettle, but instead of having it drift from 212 to 200, then re-boiling, I wanted it to stay at a set temp. It seems they could build that in to a model with relative ease.