By means of a Relay, employed to drive a water pump, this circuit provides automatic level control of a water reservoir or well. Parts: R1,R...

This design is derived from the portable Headphone Ampliflier featuring an NPN/PNP compound pair emitter follower output stage. An improved ...

Some lovers of High Fidelity headphone listening prefer the use of battery powered headphone amplifiers, not only for portable units but als...

This unit is intended to be connected to an existing car stereo amplifier, adding the often required extra "punch" to the music by...

This circuit measures the distance covered during a walk. Hardware is located in a small box slipped in pants' pocket and the display is...

This circuit is intended for children fun, and can be installed on bicycles, battery powered cars and motorcycles, but also on models and va...

This circuit, enclosed in a small plastic box, can be placed into a bag or handbag. A small magnet is placed close to the reed switch and co...

A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist's workbench. This circuit is not an absolute nove...

This circuit has been designed to provide a clearly visible light, formed by 13 high efficiency flashing LEDs arranged in a pseudo-rotating ...

This circuit was developed since a number of visitors of this website requested a timer capable of emitting a beep after one, two, three min...

These units can be useful as a short-range, single-channel remote-control. When the pushbutton in the transmitter circuit is briefly activat...

The purpose of this circuit is to animate shop-windows by means of a capacitive sensor placed behind a post-card-like banner. The card is pl...

A blinking arrow can be a very attractive gadget, suitable for many indication purposes. This circuit provides a bar-mode sequencer driving ...

These circuits were designed on request. Both feature a flashing LED that, after a preset number of flashes will illuminate steadily until P...

This circuit generates an astonishingly real imitation of the chirping of the cricket. A suitable audio wave form is generated by IC2 and re...

This accurate one-pulse-per-second clock is made with a few common parts and driven from a 50 or 60 Hertz mains supply but with no direct co...

This design was developed by request of a correspondent having made a sort of LED candle and needing to switch off the LED with a puff.This ...

This timer was designed mainly to switch off a portable radio after some time: in this way, one can fall asleep on the sand or on a hammock,...

Short circuits or broken pcb tracks can be easily recognized by means of a Multimeter, but this tool can give wrong results when testing the...

A Battery-status Indicator circuit can be useful, mainly to monitor portable Test-gear instruments and similar devices. Parts: R1,R7________...