Fermentation Control System
Originally uploaded by mikeysklar
This week I've been assembling electronics for an ice chest hack that will hold a specific temperature for a prolonged period. Its use will be fermentation, which usually requires a hold of 60F-90F for a duratino of a few hours to several weeks. The control system I created allows the user to set a desired temperature and follow the progress via a LCD or on-line via pachube for data logging purposes. Holding the actual temperature will be done with a peltier unit because it can both cool and heat for which I will build the H-bridge circuit. Today you can see the schematic and breadboard. Feedback is welcome.
3 comments:
Great project Mikey! I'm curious to know how you get the temperature sampling with the LM35. I built a sort of similar unit to regulate the temperature of a mini-fridge/keg cooler with LCD display a while back on Instructables . Still haven't quite worked out all the bugs with the temp. monitoring in the code though.. need a better average of readings I think (could never get a stable reading). Just bought a couple of Dallas DS18S20 1 wire temp. devices to use instead of the LM35, will see if I can get them to work any better...
The LM35 outputs 10mV for every 1 degree C. I read the 10mV with a ADC pin and average 100 readings to get stable temperature data. It is quite accurate for fermentation purposes.
I have seen some other keg chiller projects which are similiar, but most of them didn't have the ability to go warm enough to make tempeh. I also didn't want to have to buy a fridge which has a compressor that uses a lot more juice than a peltier.
There is a good tutorial on the LM36, LM35 that ladyada put out recently.
http://www.ladyada.net/learn/sensors/tmp36.html
Thanks, I'll check out the link. I was doing an average of 10 readings.. didn't think to go to 100 but it make much more sense for increased accuracy.
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