Generator Room Light
At night when power fails, one finds it difficult to reach the generator to start it. Here is the circuit for a generator room...
Photometer
An illuminance of 100 to 1000 lux is required for reading and doing close work without eye-strain. Specular illumination or bright sunlight provides 50,000...
Leakage and Continuity Tester
Here is a simple, chargeable leakage and continuity tester that can be operated in two modes: normal mode and gain mode. The gain mode...
Pyroelectric Fire Alarm
Here is an ultra-sensitive fire sensor that exploits the direct piezoelectric property of an ordinary piezo element to detect fire. The lead zirconate titanate...
Triple Mode Tone Generator
Here is a simple triple mode tone generator circuit that generates three different tones. You can use it as a call bell, burglar alarm...
Spy Ear
What binoculars do to improve your vision, this personal sound enhancer circuit does for listening. This light-weight spy ear gadget produces an adjustable gain...
Green LED Flashlight with 555 Timer
Here is a simple green LED flashlight built around a 555 timer IC (IC1) and powered from a 3V battery pack.
Green LED-based flashlights are...
SMF Battery Guard
The emergency light is an automatic system in which a rechargeable battery-operated light source turns on as soon as the mains power fails. When...
Metal Detector Circuit Using Difference Resonator
Described here is a simple metal detector circuit that can detect metallic conductors in its vicinity up to a range of 25 to 30...
Digital Camera Adaptor
You need not be disappointed next time your digital camera shows low battery indication during a picnic trip. Just plug this digital camera adaptor...
Programmable Electronic Dice
Here’s a simple programmable electronic dice with numeric display. This dice can be programmed using a 4-way DIP switch to display any random number...
Electric Fly Swatter
None of us likes bugs at home. To kill these flying insects, they should first be attracted and then electrocuted. An electric fly swatter...
Remote Controlled Musical Bell
This is a circuit for a knock alarm that uses a piezoelectric plate to detects vibration due to knocking and activates an alarm for about ten seconds.
Electronic Combination Lock
This 7-digit combination lock can be easily hard-wired for any combination that you choose. The circuit uses a 4-bit, divide-by-8 Johnson counter (IC1), ten pushbutton switches and npn transistor T1
Muscular Stimulator
Here is a circuit that stimulates nerves of that part of your body where electrodes are attached. It is useful to relieve headache and...
Room Sound Monitor
With this simple sound monitor circuit, you can secretly listen to conversations going on in a room. The circuit is very sensitive and powered...
Smart Hearing Aid
Normally, hearing aid circuits consume battery power continuously once they are switched on. The smart hearing aid circuit given here saves battery power by...
Wireless Switch
Normally, home appliances are controlled by means of switches, sensors, etc. However, physical contact with switches may be dangerous if there is any shorting....