building a controller for my smoker..

:mod: here something for the technically inclined amongst us. .:mod:
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Since I have to cool down my cooking and smoking adventures a bit after a recent Hospital adventure, I have been spending my time in my office, mainly to keep busy and exercise my brains a bit... (although I climb on my recumbent bike every once in a while too.. ).

- I'm building and programming a "smoking" controller using some open source (& pretty cheap..) hard- and software.. (ARDUINO);

for the prototype I'm using an Arduino Uno board:
* with a 20 character x 4 lines LCD
* and some other misc. hardware.. (and 4 MAX31855 chip - I2C thermo couple interfaces..)
* using 4 thermo couples; to measure smoker temp and allowing a maximum of 3 meat probes to be hooked up in case I smoke different stuff at the same time..

I'm writing the software to control all this stuff :
* allow setting the individual alarm temperature levels for each meat temp probe if hooked up..
* displaying all 4 temperatures, while continuously checking the meat temp levels against the alarm settings for each meat probe....
* if any meat temp reaches the alarm level - I sound a buzzer !!

I figure the whole boxed hardware + probes will cost me < $100 after I have the design complete.

Since my smoker is a gasser I'm thinking about eventually also controlling the smoker temp by hooking up the gas valve to a stepping motor driven by my software..

for folks with an electric smoker regulating the smoker temp would be a lot easier (just hook up a relay to regulate (= switching on and off) the power to the smoker...)

here the web site for the Arduino stuff..
http://www.arduino.cc/

TcircleT said:

Impressed. Can you set an alarm for low temps also?

Click to expand...

you mean - sound alarm when temp is lower than X degrees ?

Yes - you can - we even can go to to negative temps with the type K Thermo couples I use....

you just have to set the alarm levels to the desired temps for the probes you want to monitor....

and then it's all in the software you write...
you just do a compare: if equals or less than x degrees
instead of a compare: if equals or larger than x degrees

the MAX 31855 chips come in different versions - interfacing to various types of Thermo couples -
http://en.wikipedia.org/wiki/Thermocouple

I'm using K type thermo couples in my design (the most commonly used for meat thermo's....)

Type K (chromel – alumel) is the most common general purpose thermocouple with a sensitivity of approximately 41 µV/°C (chromel positive relative to alumel when the junction temperature is higher than the reference temperature).[10] It is inexpensive, and a wide variety of probes are available in its −200 °C to +1350 °C / -330 °F to +2460 °F range. Type K was specified at a time when metallurgy was less advanced than it is today, and consequently characteristics may vary considerably between samples.

Hagisan said:

Under what platform is the application being written? They have several Android and other guides out there on the interwebs.

Click to expand...

mine uses the Arduino IDE.. which has some standard libraries..
and you can add most C type code and it compiles OK.

Arduino hardware is based on the AVR atmega microprocessors

The microcontroller on the board is programmed using the Arduino programming language (based on Wiring) and the Arduino development environment (based on Processing).

it's here..



one of my lackadaisical projects to keep me out of trouble...
a BBQ Gizmo..
I built this one, using 2 cheap Thermistor probes (instead of expensive Thermo couples) for my kid,
It handles 2 meat probes and monitors the temps -
you can select the Alarm level for each probe's temperature if you desire to do so and the box buzzes when any alarm temp is reached ..
This one I made for my Daughter in Germany..
I display 20 random alternating text lines on the bottom line when in monitor mode..
and can customize the text lines which are displayed... so you better be GOOD!!

crocker84 said:

What is the advantage of building one of these, vs using a standard PID controller (like a watlow), besides the obvious fun/cool factor?

Click to expand...

Don't really know - just to keep busy - and write the code;
and know you can do it yourself instead of buying off the shelf..
and the fun of customizing the text output in monitor mode to suit the owners ?

the final version is pretty cheap too..
$4.95 for the Microprocessor,
$3.95 for a Nokia 5110 LCD
and about $8 per probe plus some small hardware to hook it up..