Auto Muting During Telephonic Conversation

Telephone conversation can be made disturbance-free using this simple circuit. As soon as you lift the telephone handset to converse, the TV, music system or any other appliance that may be...

PARROT-SOUNDING AC DOOR BELL

Here is a mains-operated door-bell that produces parrot-like sweet voice without requiring any musical IC. The circuit is cheap and easy to construct. The AC mains is fed to the circuit...

5-BAND GRAPHIC EQUALISER

This equaliser uses low-cost op-amps. Good-quality op-amps powered by a single voltage supply are readily available in the market. The op-amp should have a noise density of less than 24nV/ VHz,...

Circuit for UPS to Hybernate PC

Most of the low-power UPS systems available in the market do not have the facility to shut down the PC before they turn off automatically due to low battery. Some of...

LED Illumination for Refrigerators

The incandescent lamp provided inside the refrigerators glows whenever we open the door. It suffers from several disadvantages like: 1. Being a single light source, located in the upper corner, light does...

Accurate 1Hz Generator

Accurate 1Hz squarewave pulses are required in stopwatches and other digital circuits. Here is a low-cost, general-purpose 1Hz signal generator without using a crystal oscillator. 230V, 50Hz, single-phase AC mains is stepped...

LED Illumination for Refrigerators

The incandescent lamp provided inside the refrigerators glows whenever we open the door. It suffers from several disadvantages like: 1. Being a single light source, located in the upper corner, light does...

Solar-Powered Pedestal Lighting System

This solar-powered pedestal lighting system uses power LEDs for lighting. Solar energy is first converted into DC electricity by a solar photovoltaic cell and used to charge a storage battery. The...

Electronic Reminder

This easy-to-build electronic alarm will remind you of an impotant task after a preset time. It is particularly useful for housewives and busy professionals. All you have to do is set...

3V PC Adaptor

Plug this circuit into the available USB output port of your PC to get 50mA, 3V DC. So it can be used to recharge, for instance, two NiCd cells (1.2Vx2) of...