Alarm
Electronic Door Release
Description
The IC is a quad 2 input “AND” gate, a CMOS 4081. These gates only produce a HIGH output, when BOTH the inputs are HIGH. When the key wired to ‘E’ is pressed, current through R1 and D1 switchs Q5 on.The relay energises; and Q5 is ‘latched on’ by R8. Thus, the Alarm is set by pressing a single key,say one of the two non-numeric symbols. More >
Dark Activated Switch
This circuit will activate a relay when light falls to a preset level. Light level can be adjusted with VR1 and the relay contacts may be used to operate an external light or buzzer. More >
Frost Alarm activated switch
A simple thermistor triggered switch with adjustable threshold. It triggers with cold temperatures so may be used as a frost alarm or cold temperature switch. More >
Simple water detector circuit
This simple water detector circuit uses alternative voltage in order to prevent the corrosion of the electrodes. It is easy to build and uses N1 as a trigger Schmitt gate which generate the AC. If between the electrodes is a electricity conductor, for example an aqueous solution, then because of the rectification action of D1 and D2, the C4 capacitor is charging. More >
Vibration Sensor/Detector circuit
With the help of a simple ceramic piezo-electric detector it is possible to assemble an interesting and useful Impact sensor unit,which can be used to detect impact and vibration on doors, showcases, windows etc. More >
Laser-guided Door Opener
This automatic door opener can be made using readily available components. The electromagnetic relay at the output of this gadget can be used to control the DC/AC door-opener motor/solenoid of an electromechanical door opener assembly, with slight intervention in its electrical wiring. More >
ELECTRONIC SECURITY SYSTEM
This reliable and easy-to-operate electronic security system can be used in banks, factories, commercial establishments, houses, etc. More >
LASER Door Alarm
LASER-BASED INTRUDER ALARM
You can use this laser-based intruder alarm conveniently at the entrance of a hall or any other similar location to protect the same from unauthorised access More >
Gas Leakage Alarm
Here is a circuit that detects the leakage of LPG gas and alerts the user through audio-visual indications. More >