Random circuits

Here are some of over 800 projects from our free circuit diagrams database. For more, try browsing categories menu on the left.

Fading Red Eyes

This circuit is used to slowly illuminate and fade a pair of red LEDs (light emitting diodes). The fading LEDs could be installed as 'eyes' in a small pumpkin or skull as a Halloween attraction, or mounted in a Christmas tree ornament. Or, they might be used as a fancy power indicator for your computer, microwave oven, stereo system, TV, or other appliance.... [read more]

1KHz Sinewave Generator

This circuit generates a good 1KHz sinewave using the inverted Wien bridge configuration.... [read more]

Two Flashing LEDs Circuit Schematic

Here is the circuit diagram of Two Flashing LED's for different applications (such as model construction), and recreational. Having adjustable flashing speed with two potentiometers. It is the collection of a few active and passive components. This circuit is very easy to built ( a good idea for beginners ) and can be build on a general purpose pcb or on a veroboard. The complete picture and schematic of this project is shown below... [read more]

Loudspeaker Protection 2 for P.A output

The circuit protection output of power amplifiers and loudspeakers, dispose certain interesting elements, as the isolation of loudspeakers from the exit of amplifier, when is presented continuous voltage in his exit or when the temperature of heatsink, goes up excessively, providing simultaneously and time delay in the connection loudspeakers in the amplifier, so that we avoid pass in them, the known annoying noises from the charge - discharge of capacitors of supply.... [read more]

Pulse-Generator & Signal-Tracer

This simple circuit generates narrow pulses at about 700-800Hz frequency. The pulses, containing harmonics up to the MHz region, can be injected into audio or radio-frequency stages of amplifiers, receivers and the like for testing purposes.... [read more]

Simple optical switch

The 555 is proved to be the most versatile and ubiquitous IC all over the world.This is a possible use: simple inverting schmitt trigger.... [read more]