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...

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...

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,...

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....

Two of the problems commonly associated with street lights are false triggering due to slight variation in the intensity of ambient light and no control over switching action. Here is a simple switching circuit for street lights that overcomes these problem

This emergency light has the following two advantages: 1. It turns on automatically when the mains power fails, so you need not search it in...

Water level controllers are common nowadays. The automatic water level controller described here is built around a timer NE555 and inverter buffer CMOS IC...

IC1 (NE555) is used here as a clock generator. It is configured as an astable multivibrator whose frequency can be adjusted with the help...

This transmitter circuit operates in shortwave HF band (6 MHz to15 MHz), and can be used for shortrange communication and for educational purposes. The circuit...

This over/under voltage cut-out will save your costly electrical and electronic appliances from the adverse effects of very high and very low mains voltages. The...