Transmogrifox
Member
I have a cheap smoker that I bought which just has a 1500W heating element and a plug. It seems to be optimized for a 3 or 4-hour roast of a large roast or turkey and not very useful for much else.
Not knowing the default temperature range I decided to smoke some jerky and treated it like a Little Chief, left it overnight expecting that I could just check on it periodically throughout the next day. I found charred black things the next morning
Being a geek I thought, this is a nice job for a Teensy LC I did some fiddling around with the thermistor Beta-parameter equation on a spreadsheet to optimize my calculations to the 100 F to 300 F range and then got that working with an ADC input on the Teensy.
Last night I used my Teensy, a 16x2 LCD and a thermistor to guide my 9-year-old daughter through a science experiment in measuring the boiling and freezing temperature of water...and got some calibration data in the process. I was impressed that right off-the-block without calibration it was within 2 degrees of the boiling point and within 1 degree of the freezing point. This agrees reasonably well with my spreadsheet predictions by tweaking the thermistor nominal values by 3%. Math really works! AND...it's good enough for a smoker even if I don't calibrate it.
So now with a 30A contactor, a solid-state relay (optical isolation from contactor 120V coil), Teensy and LCD I have almost everything in place to smoke meat. Was turning a desk lamp on and off using a pot to emulate a change of temperature on the ADC -- all systems are "go".
I have not yet uploaded project photos, but I did scan in my hand-drawn schematic and upload the code to github. I have a sneaking suspicion I have reinvented the wheel that has been reinvented many times already, but why not share it anyway? Maybe I did it in a way that "just clicks" for somebody out there.
This is all in the vein of "There are multiple right ways to do something, pick one of them. [quote = me]"
The education value in playing with the thermistor manufacturer data and Steinhart-Hart/Beta parameter equations was great.
Anyway, the project is mature enough to start sharing progress. Hopefully by this weekend I will have it buttoned up enough to do a roast for a Saturday night meal. I'll post some photos when everything is assembled. I'm willing to post instructions/howto if there is any interest. Otherwise this will just be a "this is what I'm doing with Teensy" thread.
I won't waste space here with stuff -- everything I'm doing is here on github:
Teensy_Smoker_Controller
Thanks to Paul and all other contributors to the Teensy and Arduino ecosystem. Earlier on in my planning I was undecided whether to use an MSP430 USB stamp or a Teensy. The Teensy won because the library support made this into a very straightforward implementation. Makes me feel the money I spend on Teensy boards is well-appropriated
Not knowing the default temperature range I decided to smoke some jerky and treated it like a Little Chief, left it overnight expecting that I could just check on it periodically throughout the next day. I found charred black things the next morning
Being a geek I thought, this is a nice job for a Teensy LC
I did some fiddling around with the thermistor Beta-parameter equation on a spreadsheet to optimize my calculations to the 100 F to 300 F range and then got that working with an ADC input on the Teensy. Last night I used my Teensy, a 16x2 LCD and a thermistor to guide my 9-year-old daughter through a science experiment in measuring the boiling and freezing temperature of water...and got some calibration data in the process. I was impressed that right off-the-block without calibration it was within 2 degrees of the boiling point and within 1 degree of the freezing point. This agrees reasonably well with my spreadsheet predictions by tweaking the thermistor nominal values by 3%. Math really works! AND...it's good enough for a smoker even if I don't calibrate it.
So now with a 30A contactor, a solid-state relay (optical isolation from contactor 120V coil), Teensy and LCD I have almost everything in place to smoke meat. Was turning a desk lamp on and off using a pot to emulate a change of temperature on the ADC -- all systems are "go".
I have not yet uploaded project photos, but I did scan in my hand-drawn schematic and upload the code to github. I have a sneaking suspicion I have reinvented the wheel that has been reinvented many times already, but why not share it anyway? Maybe I did it in a way that "just clicks" for somebody out there.
This is all in the vein of "There are multiple right ways to do something, pick one of them. [quote = me]"
The education value in playing with the thermistor manufacturer data and Steinhart-Hart/Beta parameter equations was great.
Anyway, the project is mature enough to start sharing progress. Hopefully by this weekend I will have it buttoned up enough to do a roast for a Saturday night meal. I'll post some photos when everything is assembled. I'm willing to post instructions/howto if there is any interest. Otherwise this will just be a "this is what I'm doing with Teensy" thread.
I won't waste space here with stuff -- everything I'm doing is here on github:
Teensy_Smoker_Controller
Thanks to Paul and all other contributors to the Teensy and Arduino ecosystem. Earlier on in my planning I was undecided whether to use an MSP430 USB stamp or a Teensy. The Teensy won because the library support made this into a very straightforward implementation. Makes me feel the money I spend on Teensy boards is well-appropriated
