Free electronic circuit design and schematic diagram
Small audio amplifier is useful for audio troubleshooting or simple audio projects. It should be a low cost and easy to build. Using integrated circuit for this purpose is the right choice. With LM380 audio amplifier integrated circuit, 2 Watts power can be delivered. For better thermal endurance, a large copper track can be printed in the board to provide […]
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This simple but complete Theremin circuit is constructed using only two inverter chip plus one regulator IC. This Theremin circuit consist of five functional blocks: power supply regulator, hand controlled oscillator, null oscillator, mixer, and filter. Here is the complete schematic diagram: Voltage Regulator and Circuit Protector The power supply regulator consist of LP2950 regulator IC, which stabilize […]
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This is a relay circuit that detect the presence of sound to activate the relay. You can use this sound-controlled relay as voice operated switch, light control, toys, or any other application that can be controlled by a switch. Just replace the switch with this relay and now you have a sound-controlled device. This circuit uses a 741 operational amplifier […]
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Logic power control of analog regulator can be useful in application where a digital circuit/controller need to control power source, such as in EEPROM programmer or other power controls. This is a circuit provide ON-OFF control for 78xx regulator using digital (TTL or CMOS) signal level. This circuit uses transistors in series with the 78XX regulator, which it’s base is […]
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Normally, Theremin works by detecting hand proximity using capacitive coupling method. A Theremin circuit shown in the schematic diagram below use different method to control the pitch. The oscillator of this tone generator, both the volume and frequency are controlled using LDRs, a light sensitive electronic component, so we can call this circuit an optical Theremin. Look at the following […]
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Sferic signal simulator is used to produce an impulse signal which simulates the waveform of a sferic, a radio atmospheric signals produced by a lightning strike. In time domain, the waveform of a sferic signal is a single high amplitude spike. When this pulse is analyzed in frequency domain, it will show a wide band spectrum ranging from few kilohertz […]
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Theremin circuit shown in this schematic diagram uses digital component, so we can call it a digital Theremin. This circuit employs logic inverter 74C04 or CD4069 hex inverter and CD4046 phase-locked-loop (PLL) IC. The CD4069 logic inverter is operated as a fixed-frequency oscillator with frequency around 100kHz. The CD4046 is operated as a variable frequency oscillator which is adjustable around […]
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