DIY Electronic Horn Circuit
Here’s a simple circuit of an electronic horn that is built around quadruple op-amp IC LM3900 (IC1). IC LM3900 has four independent op-amps (A1...
Teleremote Control
Here is a teleremote circuit which enables switching ‘on’ and ‘off’ of appliances through telephone lines. It can be used to switch appliances from...
SLEEP SWITCH CUM WAKE TIMER
Here is a sleep-switch circuit that can be easily converted into a wake-up timer. A dual-mode time setting makes the system versatile. The circuit...
CORDLESS PHONE BACKUP
Normally the base of a cordless phone has an adaptor and the handset has Ni-Cd cells for its operation. The base unit becomes inoperative...
PRECISION DIGITAL AC POWER CONTROLLER
Triacs and SCRs are extensively used in modern electronic power controllers—in which power is controlled by means of phase-angle variation of the conduction period....
Handy Zener Diode Tester
Here is a handy zener diode tester which tests zener diodes with breakdown voltages extending up to 120 volts. The main advantage of this...
SMART PHONE LIGHT
The circuit shown here is used to switch on a lamp when the telephone rings, provided that the ambient light is insufficient.
The circuit can...
CLAP REMOTE
An infra-red or wireless remote control has the disadvantage that the small, handy, remote (transmitter) is often misplaced. The sound operated switch has the...
CD-ROM DRIVE AS DIGITAL AUDIO CD-PLAYER
ACD-ROM drive can be used as a stand-alone unit for playing digital audio CDs without interfacing with a computer. The stereo output of CD...
Build a Crystal-Controlled 12 MHz AM Transmitter Without LC Tuning
The main feature of this transmitter is that it is free from the LC (inductor, capacitor) tuned circuit and operates on a fixed frequency...