Optical Smoke Alarm

An optical smoke alarm (also called photo-electric smoke alarm) works using the light scatter principle. The alarm contains a pulsed Infra red LED which pulses a beam of light into the...

Touchless Doorbell For The Post-Covid World

This low-cost, simple, reliable, and effective circuit for a doorbell works without touching. It can be quite useful in our post-Covid-19 world as it minimises the spread of virus through doorbells. Circuit and...
Battery Discharge Measurement Circuit

Battery-Discharge Measurement Circuit

Battery-life measurement for a portable system is a time-consuming task and many methods used for it do not give reliable results. Presented here is a circuit using which you can measure...

Audio Mixer With Multiple Controls

When recording sound from several orchestral instruments being played by different musicians using a single microphone, the only way to adjust the sound balance is to change the position of the...

Make Your Own FM Transmitter For Broadcasting

This is one of the simplest FM transmitters that can be built. It does not require any tuning, and transmit frequency is crystal locked to 90MHz. It eliminates frequency drift common...
blown fuse indicator

Blown Fuse Indicator

A fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal wire or strip that melts when too much...
The author’s prototype of USB Mp3 player

USB MP3 Player

If you go to the market to buy an USB MP3 player, it will cost around 500 rupees or more. But you can assemble one for yourself for 150 rupees or...
Photodiode Based Fire Detector

Photodiode Based Fire Detector

This ultra-sensitive photodiode based fire detector protects your electronic devices like computer and television set. It uses a photodiode as the fire sensor and sounds an alarm immediately on sensing a...
6W+6W Stereo Amplifier

6W+6W Stereo Amplifier Using LA4440

Here is a simple project of a 6W+6W stereo amplifier using a 14-pin LA4440 IC. This amplifier can deliver an output power of 6W on a 4-ohm speaker (6W each on...
Voltage Regulator as Audio Amplifier

Voltage Regulator as Audio Amplifier

LM338 voltage regulator can also be used as an audio amplifier. The output voltage can be controlled by varying the IC’s reference voltage (pin 1), which is reflected as the output...
 
 
 

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