Verify I can dump my 12/24 SSR?
New DuetWifi, switching from RAMPS. On RAMPS I had a 24V supply for the bed heater only, controlled through a 12V SSR so everything was 12V on the RAMPS side.
Hooking up with the shared gnd as per https://duet3d.com/wiki/Wiring_and_hardware_differences_from_RAMPS_etc. I think I can have both the 12V and 24V PSUs wired in without the SSR.
It seems like this is the case with the negative side switching and various comments I've found on this forum, but nothing I've found explicitly says those two PSUs can be different voltages with this configuration - and I really don't want to hurt my new toy this early on
So, for the really pedantic folk like me, is this ok?
Best way convert your heater's and fans to 24 Volt and run everything at 24V
You only need to use the SSR if the bed heater current is greater than 18A. Yes you can use different voltage PSUs for the bed heater and the Duet if you wire the bed heater as explained. We specifically allowed for this in the design. If the bed heater voltage is lower than the Duet VIN voltage, then the bed heater LED may illuminate all the time and just get brighter when the bed heater is turned on; but that doesn't matter, and in any case you have the voltages the other way round.