Free electronic circuit design and schematic diagram
Crystal Colpitts oscillator can be implemented using a transistor and a parallel mode crystal. Here is the schematic diagram of the circuit: In this circuit, the crystal acts as an inductance. A large value capacitive divider is used between gate, source, and ground, and a small series capacitor is placed in the crystal circuit. You should choose the components values […]
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More efficient lead acid battery charger can be implemented using switch mode circuit. A switch mode for lead acid battery charger can be constructed using bq24105 battery charger controller. The bq24105 was originally designed to charge single-, two- or three-cell Li-ion and Li-polymer battery packs. Its features doesn’t include the control for lead acid battery charger termination. Here we add […]
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As the price of security camera going down, installing the camera in the shop, office, or even in home becomes economically feasible. Providing a dedicated monitor for every installed camera is not efficient, and your CRT monitor might suffer phosphor burn if it used to display static image from only one camera. To display 1, 2, 3, or 4 cameras […]
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This power factor controller accept voltage from 90 to 268 Vac, that’s why we call it power factor controller with universal input, since any standards of mains supply in almost any country would fall within that range. This power factor controller is capable of handling up to 450W load. Here is the schematic diagram of the power factor controller circuit: […]
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This FSK demodulator convert the FSK signal to serial digital signal. FSK modulation is used to transmit digital serial data, and we need to demodulate it to get back the digital data at the receiver. Here is the schematic diagram of the circuit: This demodulator circuit uses 2225/2025 Hz for mark/space coding, and this frequency is the answering frequency of […]
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This circuit enables you to connect your camera with very long wire. The circuit is actually a video amplifiers. At the sender part, the amplifier is used to make a stronger signal. This stronger video signal then can be transmitted through the long cables. The signal is transmitted using balanced mode, where two wires are driven in the opposite phase. […]
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This constant current constant voltage SMPS can be used to efficiently charge a battery. This circuit gives 7.2V at constant voltage mode, and 600 mA at constant current mode. Here is the schematic diagram of the circuit: The mechanism is simple, when the load impedance is high, then the output voltage will be constant at 7.2V. When the load impedance […]
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