Temperature Monitor for Electronic Equipment
As most electronics components’ characteristics vary with temperature, they are selected as per expected operating temperature range of the equipment. So it is important...
Stereo audio Distribution Buffer for headphones
Most audio signal sources have only one stereo output, which means they can drive only a single pair of headphones with a resistance of...
Wireless PA for Classrooms
In large classrooms, many a times the teacher’s voice is not audible to students in the back rows. So the teacher have to literally...
AC-Powered Led Lamps Without rectifiers
Usually, LED lamps require rectifier when connected to the AC mains power supply. Electrical isolation of the LED lamps from the mains is also...
Bedwetting Alarm
Bedwetting is one of the most common childhood problems that can have a significant impact on a child’s health if left unattended. During the...
Cable Tester
Have you ever wondered if a particular cable is delivering mains power supply to your device or not? Here is a solution that helps...
Cupboard Light
Here is a simple circuit that can temporarily illuminate your cupboard or other such usually dark places where mains connection is either not possible...
Remote Controlled Wireless Doorbell
This circuit lets you wirelessly control an appliance from a remote place by using a wireless doorbell. The appliance is triggered by the signal...
FM Bug
This FM bug transmitter circuit will let you spy on people. The transmitter can be placed in the desired room and the conversation heard...
Simple Stereo Level Indicator
Usually, low-priced home stereo power amplifiers don’t have output level indicators. An output power level indicator can be added to each channel of these...
Rainbow Clock
Here is a simple circuit using different colour LEDs that makes your clock glow in different colours of rainbow. The clock’s dial (shown in...
Phone Bell Auto Silencer
Telephone ringing all of a sudden in the middle of a serious meeting is quite irritating. The automatic bell silencer circuit described here is...
RGB LED Showcase Light
RGB LEDs are capable of generating a variety of colours by mixing red, green and blue colours. It is sometimes very interesting to replace...
Mixer and Preamplifier for String Instruments
Most of the small musical bands have up to four string instruments like guitars and violins. The signal from the transducers of these instruments...
Telephone Sentry
It is quite common to find extension phones in homes these days but this kind of convenience also comes with a distinct disadvantage: the...
Parked-Vehicle Highway Flasher
Often, at night, a speeding vehicle rams into another vehicle parked at the edge of a highway. Cars have parking flashers, but trucks, buses...
Solar Lamp With Variable Power Supply And Charger
A simple circuit of a solar lamp with variable power supply and charger is described here. It is useful where mains power failure is...
Simple Morse Code Trainer
Morse code contests are still held in some parts of the world. Practising the Morse code with a simple Morse key kit is interesting.
The...