Stereo Headphone Amplifier
Here is an inexpensive circuit for a stereo amplifier to drive a low-impedance headphone set. The circuit uses a few cheap transistors (BC547 and...
Whisker for Robots
Whiskers for robots are simple switch-type sensors that work like an animal’s whiskers detecting nearby objects in the environment. When disturbed, the sensor sends...
KNOCK ALARM
This circuit (Fig. 1), used in conjunction with a thin piezoelectric plate,senses the vibration generated on knocking a surface (such as a door or...
Night Lamps
Here are two night lamp circuits using LEDs. One could be used as a night-vision clock and the other as a TV lamp. Both...
Musical Water Shower
Won’t it be nice to have music playing in the background all the while when you take a shower? This simple circuit does the...
Traffic Baton
In small towns, there are no traffic lights and the police regulate the traffic with hand signals. Since their hand signals may not be...
Traffic Controller
This simple traffic controller can be used to teach children rudiments of traffic rules.
The circuit (shown in Fig. 1) uses readily available components. It...
Hot-Water-Ready Alarm
Electric kettles turn off automatically when water has boiled. What if the boiler beeps to alert you when your water has boiled? The tripping...
DIY Touch Alarm
This is a new type of touch alarm that uses an RF oscillator at its input. One special feature of this touch alarm is...
DIY Electronic Heart
With this electronic heart glowing on and off, you are sure to steal the heart of that special someone. The circuit uses an NE555...
CAR ANTI-THEFT GUARD
Here is an easy-to-build car anti-theft guard. The circuit, shown in Fig. 1, is simple and easy to understand. When key-operated switch S2 of...
MOBILE BUG
This handy, pocket-size mobile transmission detector (Mobile Bug) can sense the presence of an activated mobile phone from a distance of one and a-half...
Line-Powered Two-Tone Ringer
Need often arises for having an extra telephone ringer in another room to alert you of an incoming call. A low-cost, 2-tone ringer IC...
DIY Laptop Theft Alarm
Protect your valuable laptop against theft using this miniature alarm generator. Fixed inside the laptop case, it will sound a loud alarm when someone...
Remote-Controlled Firecracker Igniter for Safe Celebrations
Firecrackers are normally ignited by using a matchstick or a candle. You have to run away quickly after igniting the fuse of the firecracker....
Build a Flashing UFO Toy with Lights and Sound Effects
This unidentified flying object (UFO) is nothing but an electronic toy depicting the fantacy. It comprises three separate sections, viz, rim flasher, dome flasher...
Automatic Darkness-Controlled Lighting System
Make tubelights automatically switch on at night and switch off in daytime using this automatic control system. Automatic darkness-controlled lighting system means that whenever...
Contactless Telephone Ringer
This fully transistorised, simple circuit designed as a contactless telephone ringer provides an indication of incoming telephone call at a remote site like kitchen...