[Unclenick]

Well, the relay function here and the circuit I drew are just for switching the power to the oscillator circuit to turn it on and off. I figure if we have an open source design, that will mean the circuit and its components and circuit board layout will all be part of the package that is maintained. Adding the MOSFET on/off switch to the board then becomes a trivial addition. A simple 555 circuit could be the control timer, unless it is felt that digital is a must.

But if the timing goes digital, or we talk about adding a BASIC Stamp or Arduino or Raspberry Pi piggy back board or some other added degree of sophistication, then the MOSFET opens up the possibility of power control by pulse width modulation. That would let us heat fast at high average current, then back the average current off to hold a temperature for some predetermined amount of time. There are some long wave IR camera modules now that could be used to indicate the case temperature and adjust the modulation accordingly. We can make this as simple or as complicated as we want to.