I am interested in designing with cartridge heaters to implement a temperature control system, with a microcontroller sampling temperature sensors and controlling heating elements. I will probably aim for a cartridge heater since they are cheap.
I was wondering if there are any novel circuits or parts for controlling the temperature of a cartridge heater from a microcontroller. The microcontroller is capable of generating a DAC output, if that helps.
My plan was to have the uC control the temperature by providing a PWM square wave into a solid state relay, controlling the duty ratio of the power. I am unsure if cartridge heaters will naturally average the power into an average temperature, or if they get upset from transients.
Also, I'd like to put in as much safety checking as possible. I'd like an open-loop device that can remove power (and keep the power off until a system reset) if something catastrophic happens causing the temperature to run away.