Oscillators Circuit Diagrams

# Three-component Oscillator Schematic Circuit Diagram

At first glance, this circuit appears to be just a primitive microphone amplifier. Why then is the title of this article ‘Three-component Oscillator’? The answer is very simple: the microphone is not intended to pick up speech; instead, it is placed so close to the loudspeaker that massive positive feedback occurs. Here we intentionally exploit an effect that is assiduously avoided in public-address systems — the positive feedback results in a terribly loud whistle.

The loudspeaker is connected directly to the 12-V supply voltage and the power transistor, so it must be able to handle a power of at least 1.5 W, and it should have an impedance of 8 to 16 Ω.

An outstanding candidate can be cannibalized from an old television set or discarded speaker box. The microphone should be a carbon powder type from an old-fashioned telephone handset. If you place a switch in series with the power supply, this sound generator can also be used as an effective doorbell or siren. Surprisingly enough, the circuit can also be used as a simple microphone amplifier — hardly hi-fi, of course, but still usable.

An amplifier, electronic amplifier, or (informally) amp is an electronic device that can increase the power of a signal (a time-varying voltage or current). It is a two-port electronic circuit that uses electric power from a power supply to increase the amplitude of a signal applied to its input terminals, producing a proportionally greater amplitude signal at its output.

An amplifier is an electronic device that increases the voltage, current, or power of a signal. Amplifiers are used in wireless communications and broadcasting, and in audio equipment of all kinds. They can be categorized as either weak-signal amplifiers or power amplifiers.
Amplifiers are usually designed to function well in a specific application, for example, radio and television transmitters and receivers, high-fidelity (“hi-fi”) stereo equipment, microcomputers and other digital equipment, and guitar and other instrument amplifiers.
Types of amplifiers
• Amplifier.
• Audio Frequency Amplifier.
• Intermediate Frequency Amplifier.
• R.F. Amplifier.
• Ultrasonic Amplifier.
• Operational Amplifier.

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