Thank you to Mark for sharing this design, So in the same spirit of customization I've taken this design to made 12V version with 2 relays, with a minor difference.
This is something that I really need to apply to a pair of APEX SR200 with a 625VA transformer.
I also need 12V for this project.
The CD40106 with 12V have a larger Hysteresis Voltage ( ~2,5V with 12V and 0.9V with 5V) so i readapted the R/C circuit to choose one of 3 possible delays (0.5, 1, or 2s). i can also adjust shorter or longer with the selector who have the possibility to have 2 or 3 resistances an parallel, I have to work and test little bit more to adapt better the values.
I'd like to get any comments on the PCB design before I send it to be manufactured. I should have spare PCBs if there's any interest in this version, and can share the Gerber files too.
I will do also an other version with 4 layers to double the high voltages tracks on the PCB.
Thanks