DIY Digital Controller

[mhoy]

Still a work in progress since it currently uses a simple on off (and I have to figure out how to program the buttons still). So for now, it's a compile time temperature setting.  :o  Lucky the box is easy to open. I expect to add in a PID program in the near future.

There is a master on/off, input power plug, an output heater control, one K-thermocouple input, 4 buttons, Cyrdom D1210, 2x16 LCD screen and a very simple program loaded on the Arduino UNO. There is a TC4 thermocouple/controller shield and an LCD controller.

It's all housed in a large 6"x8"x3" Radio Shack box mounted internally on some 1/4" plywood.

Here are the internals before the wiring was all finished


Back of the top with buttons and LCD controller before being wired up.


Working system:



Mark

[squirtthecat]

Nice job so far!

[beefmann]

looking good

[muebe]

Nice! What are the costs for the parts?

[mhoy]

It's cheaper to buy a pre-built system. :-)  However there are 4 thermocouple inputs and numerous additions that are a piece of cake for an Arduino based system. (Bluetooth Remote control interface with serial logging comes to mind).  The main designers of this card are building it for control of coffee roasters (another hobby of mine).  Coffee roasting is a fairly complex job and the beans eventually generate heat in an exothermic reaction...so I figured I'd control my smoker first. (Btw: This would also make for an excellent Sous Vide controller).

Here is a guestimate of the parts:
$30  Arduino Uno
$16 TC4 board with surface mounts pre-installed, $6 for a bare board, $45 assembled
$15 LCD Adapter board with surface mounts pre-installed, $6 for a bare board
$13 2x16  LCD 5v
$15 Crydom D1210 (new from eBay)
$20 misc electrical components if you didn't get a pre-assembled board
$20 Misc: box, on/off switch, thermocouple mounts, terminal block, wire, crimp connectors, PC power cord cut in 1/2
   $4 5v-9v DC voltage wall transformer (old cell phone charger from the junk bin, mine was sitting in a box)
------
$133

TC4 Shield code
http://code.google.com/p/tc4-shield/

If you are interested in the TC4 and LCD control board see:
http://www.mlgp-llc.com/arduino/public/arduino-pcb.html

Mark

[devo]

Wow way over my head.

[Keymaster]

Very impressive, thanks for sharing :)

[OU812]

My head hurts now.  ;D

[mhoy]

It's probably easier than you realize. It's almost entirely plug and play with a bit of programming.  At this point I'm only turning the element on/off if the temp is under/over the desired temperature.  It gets interesting if/when I add in a PID program loop.  I'm curious how close a simple on/off can keep the temp in the smoker.

Time for the good part, I'm going to brine up some more salmon so that I can get the testing started!!!!

Mark

[squirtthecat]

That's awesome.   Thanks for the code links.

[mhoy]

ARGH, I'm pretty sure the main heating element burnt out 80% of the way through my smoked salmon!  Even reverting to the built in circuit yields no heat from the back element. Turning on the oven for the 175 part of the cooking...

Mark

[mhoy]

Bradley shipped a new element and a bottom plastic cover and it took only a phone call. Very good service. I picked up a spare element while I was at it and they shipped with the replacement parts for free. I was only down for the week. Time to get cooking again, smoked chicken anyone?

Mark

[NePaSmoKer]

Nice job on your controller


But way over my head

SO

[Michaels Place]

Nice piece of engineering work!  Have you considered selling the design to Bradley? What I don't understand is why Bradley would not build better controller technology into their own product?  Obviously they make a great product but I am just now getting very clear that the temperature swings make it difficult to produce certain foods, such as sausage or fish, without augmenting or overriding their built-in digital controller.  Anyone know if they have any plans to address this issue?

[mhoy]

Thanks for the complement, but this is an elementary controller, I've not even turned PID on yet.  :) It will only get interesting when remote BlueTooth control gets added so that I can watch the BBQ from inside on my cellphone or computer and adjust it while watching TV.  ;D  Although if I do this, it makes it hard to convince anyone that I'm slaving over the hot coals making a delicious bbq for supper.  ;D

Bradley has a digital version which I'm assuming has much better temperature control. Remember that it all costs money to implement and get appropriate certifications. The OBS seems to have CSA. I know that some tools don't even get brought into the country from Europe without UL and many nifty things just don't get here.

Mark