P-J, I have a similar setup with a PID and a rotary knob, but would like to use the same SSR to control my element. Space is a concern in my salvaged control panel and so I'd like to use only one SSR and switch control of the element between a PID and a hacked PWM dimmer from here:
LED Dimmer PWM Hack. The dimmer does not require an SSVR and can output an appropriately pulsing DC signal with the change of one capacitor.
I'd like to use my two-way selector switch to change control of one common SSR between either of the two control sources. Would it be as simple as using that to select the positive signal to the SSR between the PID and the PWM? Is it ok to have both negative wire leads being sent to the SSR unabated and simultaneously and only switch the positive signal? Or would I have to add some extra contact blocks on my switch and switch the negative signal as well? I have a slick Eaton M22 two-way switch with stackable contact blocks and have the flexibility to expand it to control more than one signal.
Thanks in advance.