FREE
circuits!
Alarm circuit diagrams
August 3, 2010
This Keypad is suitable for the Modular Burglar Alarm. However, it has other applications. Entering the First Four Digits of your chosen Five-Digit code - will energize the relay. Entering the Full Five-Digit code -... [more]
August 3, 2010
If you use a lamp with a motion sensor for outdoor lighting, the original electrical switch is actually no longer necessary. If you replace the switch with the circuit described here, an acoustical signal will... [more]
circuit from:http://www.extremecircuits.net/2010/05/bell-alarm.html
August 3, 2010
Protect your valuable laptop against theft using this miniature alarm generator. Fixed in-side the laptop case, it will sound a loud alarm when someone tries to take the laptop. This highly sensitive circuit uses a... [more]
circuit from:http://www.extremecircuits.net/2010/05/laptop-protector.html
August 3, 2010
This circuit, enclosed in a small plastic box, can be placed into a bag or handbag. A small magnet is placed close to the reed switch and connected to the hand or the clothes of... [more]
circuit from:http://www.extremecircuits.net/2009/07/mini-alarm.html
August 3, 2010
A complementary transistor pair (Q2 & Q3) is wired as a high efficiency oscillator, directly driving the loudspeaker. Q1 ensures a full charge of C2 when power is applied to the circuit. Pressing on P1,... [more]
circuit from:http://www.extremecircuits.net/2009/07/powerful-security-siren.html
August 3, 2010
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 from the mains so that low-voltage (12V) cabling could... [more]
circuit from:http://www.extremecircuits.net/2010/05/remote-alarm-for-smoke-detector.html
June 22, 2010
This is an infrared gate with two sensors planned to use in the wall in the way behind a door. [more]
June 22, 2010
A crucial failing of proximity detectors is their unreliable and tricky nature. This is where they are used to detect humans, not to speak of smaller living beings. [more]
This category