24Vac, 24Vdc or 12Vdc universal input interface to 3.3V microcontroller

[Harald Kapp]

yeah, that was my first comment suggestion way back in post #8

Sorry I didn't catch that.

 

[gicolas]

Thank you. It works properly now.
I changed the T3 transistor BC547 to a 2N2222 for an higher Ic current.
Also changed the relay from a 3V relay (max pick up voltage at 2.1V- 120mA, I was giving it 3.3V) to a 5V relay (max pick up voltage of 3.8V - 50mA)