|This is a simple - easy to build - battery powered alarm system. When it's activated - it will sound the siren for a fixed length of time - and then switch off. The extremely low standby current ensures a good battery life. |
This is a photograph of the Battery Powered One Time Only Alarm . It has independently adjustable exit, entry and cut-off timers. When it's activated - it will sound the siren for anything up to about 20-minutes. Then it will switch off - and remain off. It will not reactivate. Although it can be mains powered - the extremely low standby current makes battery power a realistic option.
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