Remote Alarm For Smoke Detector circuit
This alarm circuit was designed to monitor a mains-powered smoke detector located in a shed (which is used to house dog kennels). It provides complete isolation...
An Enhanced Shed / Garage Alarm circuit
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 cu...
A Simple Fire-Door Alarm circuit
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 throu...
A Dozen Small Cmos Alarm Circuits circuit
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 ...
A Cmos 4060 Burglar Alarm circuit
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 - su...
A Simpler Cmos Single Zone Alarm circuit
This is a simple single-zone burglar alarm circuit. Its features include automatic Exit and Entry delays and a timed Bell/Siren Cut-Off. It`s designed to be use...
A Cmos Based Single Zone Alarm circuit
This circuit features automatic Exit and Entry delays - timed bell cut-off - and system reset. It has provision for normally-open and normally-closed switches -...
A Transistor Based Single Zone Alarm circuit
The circuit features automatic Exit and Entry delays, timed Bell Cut-off and System Reset. It has provision for normally-open and normally-closed switches and w...
An Expandable Transistor Based Burglar Alarm circuit
This transistor based alarm features automatic Exit and Entry delays - together with a timed Bell Cut-off and system Reset. Along with the Exit/Entry zone - the...
An Expandable Multi-Zone Modular Burglar Alarm circuit
This circuit features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-h...
Two-Zone Burglar Alarm circuit
This two-zone alarm has automatic exit, entry and siren cut-off timers. It was developed for the Beginner`s Guide To Cmos Timers. So it has a particularly detai...
Electronic Siren
The sound produced imitates the rise and fall of an American police siren. When first switched on the 10u capacitors is discharged and both transistors are off....
Everything-that-moves ALARM
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Electronic Locker
This circuit is an Electronic Locker. It is controlled by a switches combination (by a code). There is a switch matrix on the door of the locker. This one is a ...
UltraSonic Radar
This is a very interesting project with many practical applications in security and alarm systems for homes, shops and cars. It consists of a set of ultrasonic ...
Frost Alarm
The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees celsius. A suitable bead type thermistor is found in the Maplin catalogue. The 10...
High And Low Voltage Cut Off With Time Delay
The power line fluctuations and cut-offs cause damages to electrical appliances connected to the line. It is more serious in the case of domestic appliances lik...
Downed Model Locator
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Economy radar detector
This circuit uses a 1458 dual op-amp to form a radar detector. C1 is the detector of the radar signal. The first op-amp forms a current-to-voltage converter and...
Keys Finder
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