I know there are already a lot of topics relating to this, but I am a bit lost with what it all means. My knowledge is pretty limited and I was hoping someone can explain what I need in simple terms. As you will see from my questions, I don't know a lot about electronics.
I am using an Atmega16 and I need to switch a relay that has a coil with the following specs:-
Nominal Voltage - 5VDC
Resistance - 27ohms
Nominal Power - 930mW
Nominal Current - 185mA
I will be switching 240VAC with this relay. I am using a 5V regulated supply to power the Atmega16 so I was hoping to use the same power supply to switch the relay. But I have read about it being unwise to do this. So how do I get around this? I want to use the least amount of components as possible, would I really need to have 2 seperate regulated power supplies?
Now to switch the relay I was considering using a 4N28 optoisolator and a TIP115 transistor as I already have some of these. Would this combination be suitable? Or can someone suggest something better? With regards to the circuit, do I connect VCC to the Emitter and put the relay coil between the Collector and GND? I have some 1N4001 diodes, would one of these across the coil be required? Would I then connect the Base straight to pin 5 of the 4N28 with pin 4 to ground? I wouldn't mind lighting an LED as well, how would I work that into the circuit?
Any advice will be greatly appreciated. Thanks in advance.