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Alarms and security circuit diagrams
August 4, 2010
This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. It has provision for normally-open and normally-closed switches and will accommodate the usual input devices (Pressure Mats, Magnetic Reed contacts, Foil Tape, PIRs... [more]
August 4, 2010
This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. It will accommodate the usual normally-closed input devices (Magnetic Reed contacts, Micro Switches, Foil Tape and PIRs). And - with a simple modification... [more]
August 4, 2010
This is a single zone alarm - with automatic exit, entry and siren cut-off timers. It will accommodate all the usual types of normally-closed input devices - such as magnetic reed contacts, foil tape, PIRs... [more]
August 4, 2010
This is a selection of small self-contained alarm circuits. They have a very low standby current; and are suitable for battery operation. Some are triggered by normally-open and normally-closed switches. Some react to changes in... [more]
August 4, 2010
This is a selection of simple self-contained transistor based alarm circuits - complete with photographs. They are designed around the Complementary Latch. All may be triggered by both normally-open and normally-closed switches. They have a... [more]
August 4, 2010
Attach this circuit to the door of an unattended shop - or reception area - and the sound of the buzzer will tell you when you have a customer. Add a siren - and it... [more]
August 4, 2010
This circuit will let you know when something that should be kept closed - has in fact been left open. Attach it to a Fire-Door. It will allow you to pass through the door as... [more]
August 3, 2010
This is a basic single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays - and an optional Siren Cut-Off timer. It has an extremely small standby current. This makes it ideal for... [more]
August 3, 2010
This is an enhanced version of the simple Garage/Shed Alarm. The Entry and Exit delays have been increased to about 30-seconds - and I've added a timed Siren cut-off and automatic Reset. I've also replaced... [more]
August 3, 2010
This is a single zone alarm - with independently adjustable Exit, Entry and Siren Cut-Off timers. When the alarm is activated its Siren will sound once - for up to 20-minutes. Then it will switch... [more]
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