Unusual use of M8/M9 to control a compressor

[Doddy]

I did mean to ask why you had a diode on, thanks. The manual doesn't mention anything about back-emf or diode when connecting a mechanical relay to the isolated outputs.

Hmmm, you're right - it instead refers to a relay coil with a +/- nomenclature on the coil - okay if the relay integrates a back-emf diode - I've seen relays with these - but never experienced them myself. Worth being vigilant on that topic - otherwise you can risk damage to the AXBB. Or drive the relay through a transistor amplifier (I'd always belt-and-brace that solution - but that's just me) - either way the solution requires a back-emf diode to protect the switching device.

The MK2P-S does not integrate a diode - you need to add one. Psst, if you don't have one PM me your address and I'll pop a couple in the post - I'm heading to the PO this afternoon anyway.

[ngwagwa]

Hmmm, you're right - it instead refers to a relay coil with a +/- nomenclature on the coil - okay if the relay integrates a back-emf diode - I've seen relays with these - but never experienced them myself. Worth being vigilant on that topic - otherwise you can risk damage to the AXBB. Or drive the relay through a transistor amplifier (I'd always belt-and-brace that solution - but that's just me) - either way the solution requires a back-emf diode to protect the switching device.

The MK2P-S does not integrate a diode - you need to add one. Psst, if you don't have one PM me your address and I'll pop a couple in the post - I'm heading to the PO this afternoon anyway.

Thanks, you have PM