I have a circuit which seems to work and I would just like someone to confirm that it looks ok and isn't going to damage a 3.3/5V system (Raspberry Pi). Also, if there are improvements / simplifications I could make, that would also be great.
Basically, the circuit is used to get an old doorbell electromagnet to work to make it chime. When I set pin 24 high on my Pi, which is connected to a transistor and in turn a relay, it dings and when I set pin 24 low, it dongs.
You should know that initially I was just connecting this all straight to pin 24 on the pi which I was advised here that wasn't a good idea, so thankyou for that ;).
Below is what I put together in Fritzing to show what this version looks like. Initially, I was just trying to use the transistor on it's own, which would be simpler, but for whatever reason, that doesn't give me enough voltage to get the magnet to work -- I will understand why one day...
So any thoughts / feedback / criticism greatly received.
Many thanks, D.