My thoughts are that a variation of the existing Catuai application is the most straightforward way to test things on the Quest. Hardware needed (most of which you probably have already):
Arduino and TC4 (version 5.20 is ideal, but this should also work on older TC4's with a software setting)
Two 10K, 1-turn potentiometers to manually control the power to the heater and the fan (only required for Catuai; would not be needed once switched to Artisan)
One zero cross SSR for the heater
One random fire SSR for the fan (Crydom D2425-10, Crouzet 84137200 or equivalent)
Zero cross detection board (I would send you a prototype)
Assuming everything works with Catuai, then I would tweak aArtisan (the TC4/arduino software for Artisan interface) specifically for the Quest and you could switch to Artisan if you wanted.
Im neither a software guy, nor a hardware guy, but I find it all quite fascinating, even though, for the most part, I deep in the weeds.
I thought I had read somewhere in another post that rotational speed control of the drum was also desirable modification for some. I thinks it's a compliment to the designer of our roaster that a simple manual roaster can be modified in so many ways to automate many aspects of the roast.
As far as I know, the new Quest M3 has control of the drum speed. I don't know if it's a different motor, but the original one could be controlled by the same way Jim describe here, I just don't know if it can rotate at a higher speed than it rotates now...
I have the latest version offered by Sweet Marias. It has controls for amperage and fan speed only. I have heard dealing with the company directly can provide different options. But to add on the import duties, and extremely high shipping costs made little sense, since I was able to drive over to SM's in 20 minutes and pick it up.
