This is representation of a latching circuit that I have built at work using 4 IDEC RU4S-A110 relays. This version is a 24v DC version using RU4S-D24 minus the indication lamps built into the relay. I'm going to try building an equivalent circuit using transistors to better understand transistors.
The lamp is actually a speaker that sounds with lamps indicating the alarm condition on a different circuit.
The relays I'm using are 4 SPDT's on a common relay core with a green LED and resistors to indicate a closed condition.
