This is a photograph of a simple two-zone alarm circuit. It includes an Instant alarm zone - and automatic Exit, Entry and Siren Cut-Off timers. It can be triggered by the usual normally-closed input devices - such as magnetic-reed contacts - PIRs - and foil tape. I've used a 12-volt supply in the
Schematic Diagram - but the circuit will work at anything from 5 to 15-volts. Just choose a Relay, Buzzer and Siren suitable for the voltage you want to use.
