Build this battery / mains powered DIY alarm using common components. It's suitable for all types of premises - including caravans and campers.
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This is a photograph of a simple alarm circuit. It has automatic Entry and Exit delays. I've described it as a Garage/Shed Alarm. But it will have other uses. Although it can be mains powered - the extremely small standby current makes it ideal for battery-powered operation. I've used a 9-volt supply in the Schematic Diagram
- but the circuit will work at anything from 5 to 15-volts. Just choose a Relay and Siren suitable for the voltage you want to use.
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