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Homebrew PID Controller for my UDS.

baz senior

Smoke Blower
Joined Nov 3, 2013
I have been building a PID controller for my UDS, mostly so I don't have to keep watching it.

I have seen a few version of how others have made these, and went for the one which looked the easiest and cheapest to build,

I started with a 12 volt PID controller, which can be purchased from a certain auction website. All I needed then was a 12 volt computer cooling fan and a box to put it all in. The box is connected to the UDS with a short piece of 28mm copper pipe, and attached to the UDS with 28mm-3/4" male iron connectors and back nuts.

The PID is set to run at a certain temperature, and trained to maintain and smooth out the up and down temperature effect. It does this with clever calculus, that is able to predict when the heat is needed, and when to stop the fan to maintain an even temperature.
They are all slightly different, but basically use the same principle.

So, having put all this together, it was time to try it out. On advice from another member, (Smoker PauI Thumbs Up) ran the UDS up to temperature, and then "trained" the controller, using a function called auto-tune. This is where it monitors the variations in temperature, and begins to predict the need for heat, switching on the fan as needed.

And it works fantastically, keeping the temp to within five degree's either side of the set temp. It's been running since 3 O'clock and it's now nearly half past eight.

I'll post pics tomorrow, so you can see what I have been prattling on about.
Iam going to put a piece of Gammon in as well, to see how it fairs with food in it.


baz senior

Smoke Blower
Thread starter
Joined Nov 3, 2013
Awesome, just awesome. This worked way better than I had hoped. I called it a night at 10.30pm, and got down the garden at Eight this morning. There was still heat in what was left of the charcoal.

So after a quick clean out, I loaded it up again, with a few good chunks of Oak in amongst the coals. I had soaked a bargain bit of Gammon for six hours to get some of the saltiness out of it, and got that ready for cooking.

I lit the UDS, waited until it got to temp and then let the controller take over the running of the temp. I started it around 10.30, put the meat in at 11.30 and left it to it's own devices. I kept watching the temp on the ET-73, just to make sure nothing went wrong, as there have been one or two good gusts of wind. I wanted to make sure that didn't over-ride the controller fan.

It works fantastic. I can only assume that it is able to monitor and further correct it's control, as today it has been bang on target for the temp, it has only swung a couple of degree's either way. When you realise this is trying to control a charcoal burn, which will have varying heat output from different lump size, and quality of the wood used, plus the slow reaction to any input that is made, then this thing is cleverer than me.
It sure beats juggling lever valves.

Here's some pic's.

http://s1230.photobucket.com/user/BBQBAZ/library/PID Controller?sort=6&page=1

Roll on tea time! :nana2:


Meat Mopper
Joined Dec 24, 2006
Very nice!!!  I am gonna build one for my UDS too just need to get the pid and a box to mount it in.....

baz senior

Smoke Blower
Thread starter
Joined Nov 3, 2013
If you make it 12 Volt, you haven't got to worry about getting a shock if it gets wet or the cable gets trapped. That and if you want to, you can just connect it to a battery and your'e not reliant on a mains supply.


Joined Dec 30, 2013
Is there anything in particular that I need to look for when ordering a pid off of eBay? Did you get the thermocouple there too? Thanks for the help.


SMF Hall of Fame Pitmaster
OTBS Member
★ Lifetime Premier ★
Joined Nov 12, 2010
Very nice build..... Dave
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