Intelligent Emergency Light Switch for Automatic Darkness Detection
This intelligent switch circuit enables automatic, switching on of an emergency light system during darkness in the event of mains failure. The mains power...
LOW CURRENT, HIGH VOLTAGE POWER SUPPLY
A high voltage power supply is a very useful source which can be effectively used in many applications like biasing of gas-discharge tubes and...
Automatic Room Power Controller
An ordinary automatic room power control circuit has only one light sensor. So when a person enters,the room it gets one pulse and the...
TELEPHONE RINGER USING TIMER ICS
Using modulated rectangular waves of different time periods, the circuit presented here produces ringing tones similar to those produced by a telephone.
The circuit requires...
DIY Compact Telecom Headset Circuit for Hands-Free Communication
A compact, inexpensive and low component count telecom headset can be constructed using two readily available transistors and a few other electronic components. This...
Precision 1Hz clock Generator using Chip-On-Board
Usually the circuits for generation of 1Hz clock for applications in digital clock and counter circuits make use of ICs in conjunction with a...
Build a High-Quality Dual Power Supply for Audio Amplifiers
High-quality audio amplifiers require a very efficient power supply with negligible ripple, hum and buzz. An ordinary bridge-type power supply has a drawback in...
Telephone Operated Calling System
Dual-tone multiple-frequency (DTMF) receiver IC is commonly used in telephone equipment. One common DTMF receiver is Holtek HT9170 used in electronic communication circuits. The...
Medium-Power FM Transmitter
The range of this FM transmitter is around 100 metres at 9V DC supply.
The circuit comprises three stages. The first stage is a microphone...
A Fourth-Order Speech Filter (Based on Texas Instruments Application Note)
Human speech generally occupies an audio spectrum of 300 to 3400 Hz. There is a requirement, especially in telephone circuits, to limit the frequency...
Remote-Controlled Fan Regulator
Using this circuit, you can change the speed of the fan from your couch or bed. Infrared receiver module TSOP1738 is used to receive...
DTMF Receiver IC MT8870 Tester
Today, most telephone equipment use a DTMF receiver IC. One common DTMF receiver IC is the Motorola MT8870 that is widely used in electronic...
Simple Short-Wave Transmitter
This low-cost short-wave transmitter is tunable from 10 to 15 MHz with the help of ½ Jgang condenser VC1, which determines the carrier frequency...
FM Adaptor for Car Stereo
If your car has an FM radio with stereo output but no inbuilt cassette player, this circuit will come handy for listening to your...
DC-TO-DC Converter
Here’s a low-cost DC to DC converter circuit that converts 6V DC into 12V DC. It uses no transformer and is easy to construct...
Non-Contact Power Monitor
Here is a simple non-contact AC power monitor for home appliances and laboratory equipment that should remain continuously switched-on. A fusefailure or power breakdown...
Digital Audio/Video Input Selector
Need to connect more than one audio-video (AV) source to your colour television? Don’t worry, here’s an AV input expander for your TV. It...
9-Line Telephone Sharer
This 9-Line Telephone Sharer circuit is able to handle nine independent telephones (using a single telephone line pair) located at nine different locations, say,...