Square Wave Oscillator with Minimum Components Count

This circuit generates a square-wave which is useful as a clock signal or AC drive for the excitation of sensors. this article presents a square-wave oscillator. This circuit requires no external components unless the bypass capacitor. Figure below shows the circuit, the output frequency and a scope shot of the output waveform. AC-powered subsystems or a square-wave (clock) generator for […]

Read more

Low Cost Noise Generator

White noise is a random signal (or process) with a flat power spectral density. In other words, the signal contains equal power within a fixed bandwidth at any center frequency. To measure and test a wide band communication circuit we can use this noise. But to build the generators we need more money. This article shows the cheaper way to […]

Read more

Heartbeat Sensor (Tranduscer)

To build a heart-beat transducer not as difficult as imagined. Circuit below shows a simple heart-beat transducer. This circuit made from an infrared phototransistor and infrared LED.  This transducer works with the principle of light reflection,in this case the light is infrared.  The skin is used as a reflective surface for infrared light. The density of blood in the skin […]

Read more

AC Powered-LED Flasher

Based on a request by FreeCircuitDiagram reader Helynn Schufletowski, here we present an AC powered-LED flasher circuit for all of you! DEADLY ELECTRICAL SHOCK WARNING: This circuit is not isolated from mains supply, don’t touch it when it’s plugged to the power line. The circuit is based on our previous transistor LED flasher circuit, but we added a transformer-less ac […]

Read more

Typical Flyback Circuit

Diagram below show the typical flyback. This flyback mostly found in a direct view color television or computer monitor. The right side show us the high voltage section. This section consist of HV to CRT, focus, and screen divider network. On monochrome an black-and-white TV, the flyback transformer do not have screen divider and focus. The flyback have a ferrite […]

Read more
1 2