Free electronic circuit design and schematic diagram
This circuit is a simple buzzer circuit and it called novel buzzer. It only uses a relay in series with a small audio transformer and speaker. The relay will operate via the transformer primary and closed relay contact, when the switch is pressed. The normally closed contact will open as soon as the relay operates, removing power from the relay, […]
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This circuit included in the category astable multivibrator. This circuit is used to test N-Mosfets (the power kind e.g irf830), whether it works or not. If it is not working, the LED will not flash. If Mosfet is working it will operate in the astable multivibrator circuit causing the Led to flash. Here is the circuit diagram: To make the […]
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Electroscope is a device that is used to detect electrostatic charges. Operation: To reduce AC noise this circuit uses C1, but it will lower the sensitivity a bit. As a voltage divider we use the MPF102 and R1. The divider’s output will be about 4.5V diving a half-scale reading on M1, a 200-uA meter, when the FET’s gate is earth […]
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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 […]
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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 […]
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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 […]
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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 […]
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