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Project Help and Ideas » Automated Smoker Temperature Control

October 16, 2012
by josegmeier
josegmeier's Avatar

Hello Community,

I am not asking for suggestions or help, but any would be greatly appreciated!

I am slowly working on an automated smoker temperature control system. There will be a thermocoupler that measures the internal temp of the meat as well as a thermocoupler measuring the air temperature of the smoker. The temp will be controlled by adjusting the air speed of a DC fan motor via Pulse Width Modulation. The speed will be adjusted based on the temperature of the inside of the smoker.

I was motivated to carry out this project, because I love to smoke foods, BUT, my grill requires that I babysit it all day long, refuel, and it is a very laborious task.

This is my smoker, a very light, cheap smoker abt $40.00, that is extremely light and can be easily toted up and down the stairs on my apt building:

http://www.academy.com/webapp/wcs/stores/servlet/Product_10151_10051_27617_-1?N=77985508+4294967116

I am working with the code from the DC motors 101 and the Sous Vide program.

So far I have successfully set up the Circuit using the same code as in the DC motors 101 demo.

The next steps I will take are as follows:

1) Instead of modifying the fan speed based on the measured temperature, I will adjust the speed based on the voltage read form a potentiometer. This will enable me to experiment with my grill to find the best fan speed, via PWM that keeps the temperature as consistent as possible. I want to use logs for fuel, as professional smokers do, so I will start about half a log so that it is not on fire, but has glowing embers. The air form the fan should keep these embers burning to produce smoke and the temp that I want.

2)Develop code to read the temperature from a thermocouple to monitor the air temperature of the grill, and to control the speed of the air intake fan.

3)Develop code to change the desired air temperature of the grill.

4)Develop Code to display a reading of the internal temperature of the meat from a second thermocoupler.

5)Develop code to send data to my phone via a bluetooth connection to monitor the temperature of the grill.

That is all.

This for me will take a lot of time, but I am excited to learn!

October 16, 2012
by pcbolt
pcbolt's Avatar

Great project. The two videos should help out immensely and I know there have been plenty of forum posts on here about motors/thermocouples/ADC etc. that you can search for more help. Noter recently posted a great library article about using a Bluetooth interface chip with his smart phone. I don't know if you have an Android phone or not but the SDK is free to download so you can program your phone easily enough (Java coding experience would help).

Please keep us posted with pics and progress reports. Good luck.

October 16, 2012
by JimFrederickson
JimFrederickson's Avatar

As you are trying to use "wood" to get your smoke, I have found 2 methods that best for this...

Method 1: If you are going to use a "wood fire" then it does provide a bit more "difficulty" because you need to keep the fire burning.

Controlling the air supply to the fire is important to control how fast/hot it burns.

Method 2: Another option is to use an "electric burner" that gets hot enough to produce smoke from the wood, and that doesn't actually cause the fire to reach a combustion.

This is must easier to control, but in my experience the flavor is not quite as good.

I have found that in both cases there is a need for a "burn/smoke chamber" and then a "smoke cooling chamber" and finally the "smoke chamber".

For the "smoke cooling chamber" an "air-to-air" or in this case "air-to-smoke" heat exchanger.

No outside air mixes with the smoke, but it does cool the smoke.

I have found that the "3 chamber approach" adds more control, and time, to keep the smoke at the proper temperature.

October 17, 2012
by JimFrederickson
JimFrederickson's Avatar

Another reason to have a chamber after the burn/smoke chamber, which I forgot to mention before, is it allows some of the large particulates, read "soot", to settle out as well.

That is "usually" not a problem except when adding wood. (There are other ways around that as well though.)

November 24, 2012
by josegmeier
josegmeier's Avatar

It turns out i only really need the fan for stoking the fire. For fine tuned temperature control I am going to need to have control of the air imtake and air exhaust. I am planning on adapting code from the sois vide project to control servo motors to control the air flow. The fan will tun on if the temp plummets. I also need to create a better seal on my grill which i have some ideas for. I will keep yall updated. I smoked turkey for thAnksgiving and am smoking a pork shoulder now.

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