Free electronic circuit design and schematic diagram
Pulse width modulator produce a PWM signal, a pulse with a constant frequency but with the duty cycle vary according to a modulating signal. Here is the schematic diagram of pulse width modulator circuit using 555 IC as the active component: This pulse width modulator circuit need external pulse train input to trigger the the 555 monostable circuit. This trigger […]
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Pulse position modulator can be easily built using 555 IC. Here is the schematic diagram of the circuit: Pulse position modulator modulate the on-period while keeping the fixed off-period. Pulse position modulation might substitute pulse-width modulation in some application. The main difference between pulse position modulation (PPM) and pulse width modulation (PWM) is that unlike PWM, PPM doesn’t keep constant […]
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This LED flasher give similar circuit with the previous transistor LED flasher, but this circuit use a 555 integrated circuit chip as the active component. Here is the schematic diagram of the LED flasher circuit: This circuit gives alternating LED flashing, but with different flashing period between LED 1 and LED 2. The ON period of the LED 1 is […]
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Classic LED Flasher Circuit This LED flasher circuit is a classic two transistor flip flop. This flasher circuit is very popular and it’s usually the first circuit to build when starting electronic circuit building hobby. Here is the schematic diagram of the famous LED flasher circuit: How LED Flasher Circuit Works The circuit consist of two transistors, two capacitors, four […]
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A crystal tester circuit is very simple, it contains only oscillator and detector inside. This crystal tester circuit uses one transistor for the oscillator and one transistor for the detector. Here is the schematic diagram of the circuit: The mechanism of this crystal tester is very simple. If a good crystal is connected to the test lead, the oscillator will […]
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This alarm siren circuit produce warbling sound, you can use it in your toys or in security alarm. The circuit use two 555 IC oscillator. In this alarm siren circuit, the first oscillator is employed to produce audio frequency. The second oscillator is employed to produce a modulating signal. This modulating signal make this alarm siren generates warbling sound. Here […]
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This circuit is similar with our previous dimmer circuit, but the gate control is full-wave rectified using diode bridge. This circuit can be used to replace electric switch for your incandescent lamp, brushed motor, soldering iron or heater. Here is the schematic diagram of the dimmer switch: Please note that his dimmer switch can only work on AC voltage, it’s […]
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