Two microcontroller and a relay

[Michael Quiñones]

I have this two microcontrollers SyncMos and Arduino controlling a relay.

And also two power sources - 12v DC (VCC 2 and VCC 1).

I wanna consult the diagram below if it was correct...

 

[Harald Kapp]

D4 and D4 are reversed. With cathode to +12 V there will be now current flow. Or are the -12 V sources (your text doesn't match your diagram). If Vcc1 and Vcc2 are negative, then the diodes are correct, but the transistors are wrong. You'd have to use pnps the, but the these can't be controlled from teh controllers without an additional level shifter circuit.
Please clarify.

Why are there 2 power source Vcc1 and Vcc2 at all? A single suppply will suffice.

All grounds need to be connected.

 

[Michael Quiñones]

Sorry, D5 and D4 are reversed. What is level shifter circuit ?

Two different power sources because of the design of my circuit...

 

[Harald Kapp]

Level shifters are used to convert signals between different voltage domains. You don't need one if you have Vcc1, Vcc2 = +12 V and correct orientation of the diodes.

 

[Harald Kapp]

R2 and R4 could have a higher resistance (e.g. 10 kΩ) to minimize power loss.
For cost reasons 10 % accuracy will suffice for all resistors.

 

[Michael Quiñones]

Okie thanks a lot