Hello Chaps,
I have relay connected in my circuit as follows.
disclaimer, this circuit is representation taken from google
Where IN2 is input from my MCU which is driving the logic with 3.3v. And my Load is 230V boiler. Basically the relay is turn on/off usual bog standard central heating boiler.
The circuit above is working fine. But am starting to wonder whats the point of U3 photo-coupler, I could simply control the relay VCC which is 5V with a npn transistor and flywheel diode to counter the back emf. So U3 seems a bit of overkill.
I have relay connected in my circuit as follows.
disclaimer, this circuit is representation taken from google
Where IN2 is input from my MCU which is driving the logic with 3.3v. And my Load is 230V boiler. Basically the relay is turn on/off usual bog standard central heating boiler.
The circuit above is working fine. But am starting to wonder whats the point of U3 photo-coupler, I could simply control the relay VCC which is 5V with a npn transistor and flywheel diode to counter the back emf. So U3 seems a bit of overkill.