Relay Driver

Not the best scan in the world, but hope you get the idea. The words which are unreadable are "Relay Coil".

When your digital output is at TTL logic zero the transistor is cut-off and the relay is released. When the digital output is at TTL logic one, the transistor turns on. V_ce is nominally 0.3 VDC and the relay operates.

Good luck.

Pete