How To Build A One-Time-Only >> Burglar Alarm Circuit

  
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This alarm is designed to sound its Siren only once. That is - when the alarm is activated - the Siren will sound for a preset length of time. Then it will switch off and remain off. The alarm will not re-activate. The basic alarm has a single zone with independently adjustable Exit and Entry delays. The zone will accommodate the usual types of no
How To Build A One-Time-Only >> Burglar Alarm Circuit - schematic

rmally-open and normally-closed input devices - such as pressure mats, magnetic-reed contacts, micro switches, foil tape and PIRs. A range of Expansion Modules allow you to add any number of Instant Alarm Zones, Personal Attack Zones and Tamper Zones to your system. There`s also an Untimed Output Module. It will keep an internal sounder, strobe-light, lamp or whatever going after the siren has stopped. The alarm may be operated by a simple hidden two-way switch - such as a light switch. If you want more security - you can use a key switch - or one of a number of code operated Keypad Switches. Before you set the alarm - make sure that the building is secure - that ALL of the Green LEDs are lighting - and that the Yellow LED is off. If the Yellow LED is lighting - there`s a fault in one of the zones - and THE ALARM WILL NOT SET. Depending on the setting of R9 - when you move Sw1 to the "set" position - you have up to about a minute to leave the building. When you return and open the door - the Buzzer will sound. Depending on the setting of R8 - you have up to about a minute to switch the alarm off. If you fail to do so - the Siren will sound. Depending on the setting of R14 - the Siren will sound for up to about 20-minutes. Then it will switch off - and remain off. Of course - you can stop the noise at any time by moving Sw1 to the "off" position.



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