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....
Night Alert System
Idea of this night alert system came to me one midnight when my pet dog started barking continuously on sensing a moving shadow, perhaps...
USB Power Socket
Today, almost all computers contain logic blocks for implementing a USB port. A USB port, in practice, is capable of delivering more than 100...
Skin Resistance Meter
Human skin offers some resistance to current and voltage. This resistance changes with the emotional state of the body. The skin resistance meter circuit...
Remote Operated Switch
Generally, a bedside master switch is used to switch on lamps both indoors and outdoors when there is a threat of intruder. This remote...
Fully Automatic Emergency Light
This is a circuit for an emergency light that automatically turns on when the supply is gone and turns off when supply resumes. It is rechargeable and stops charging the battery when the battery is full.
Automated Alarm Circuit
Two automated alarm circuits are presented here. One produces bird-chirping sound and the other British police siren tone. Fig.1 shows the circuit of the...
Anti-Sleep Alarm for Students
This anti sleep alarm circuit saves both time and electricity for students. It helps to prevent them from dozing off while studying, by sounding...
Efficient Egg Candler
Candling eggs, while they are incubating, is the proven method to test them for fertility. Often, egg candling is done using a light source...
Micro-Solder Pot
To make a great solder joint, component preparation is a must. It is very important to clean component leads, wires and contact surfaces prior...
Midget Vibration Detector
This article describes a low-cost sensitive midget vibration detector that can interface directly with any microcontroller. The entire circuit operates off a single 5...
Magnet Operated Toggle Switch
When the author decided to develop a magnet operated toggle switch, what he had had in mind was an ‘unorthodox’ design that was as...
16-Way Clap Operated Switch
Control your home appliances with this clap operated switch, without getting out of your bed. You just have to clap in the vicinity of...
Continuity Tester With A Chirping Sound
Today, there’s a party at your home. And you are busy detecting faults in the decorative lights hanging over the boundaries of your house....
Shadow Alarm: Light Sensitive Circuit
This light sensitive alarm circuit sounds an alarm whenever a shadow falls on it. So it can be used at night by shopkeepers to...
Bicycle Guard
This anti-theft device for bicycles is inexpensive and can be constructed easily using a few components.
At the heart of the circuit is a wheel...