[Homeroast] heat gun method

Allon Stern allon at radioactive.org
Fri Nov 12 03:03:35 CST 2010

On Nov 11, 2010, at 12:30 PM, Bill S. wrote:

> At about the same point at which you are, I decided to buy a non-contact
> infrared thermometer. Most are good to 1000F, and I have found mine to be
> accurate in any roasting method where you can see (shoot at) the roasting
> beans.  It has also been useful for home projects where I needed to know the
> temperature of a surface.
> I addressed the air-vs-bean temperature issue by putting the probe in the
> center of the bean mass (using SM's digital thermometer, in a homemade air
> roaster, using a HG).  This way, the hot air hitting the probe has been
> through half the beans, the beans are contacting the probe, and the airflow
> over the probe is "average".  I compared readings from my non-contact
> thermometer with the probed thermometer, and found that the tempeatures were
> consistent enough for me to rely on the probe.

I've thought about setting up a heat gun with PID, using an infrared thermometer as the temperature input (linear voltage or current).
I just wonder how well the PID algorithm, as implemented in the industrial controllers I have, will deal with the variations induced by a hand-operated method, whether it will compensate adequately for them, or will be thrown off the rails.

Heck, I could just get one of these
and implement the PID algorithm on the microcontroller, plus an LED output to show process and measured temperatures.

PID library here: http://www.arduino.cc/playground/Code/PIDLibrary


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