Audio Oscillator And Audio Amplifier Uses transistors, capacitors, resistors and IC's.
Here is an interesting combination of two basic electronic ciruits,
an oscillator operating in the audio frequency range and an audio amplifier that allows a speaker to be connected to the oscillator.
By using the amplifier to amplify the output of the oscillator, you can obtain a loud sound that can be used for an alarm or anything else that requires a loud audio tone.
In this circuit I bring the emitter out to a pin labeled "key". If you bring this point to ground, the oscillator turns on. Remove the ground, the oscillator turns back off. This makes it easy to control using relay contacts, a transistor, or even an old telegraph key for code practice.
This project uses an integrated circuit or 'IC' as one of the active components. IC's
contain many parts such as transistors, diodes and resistors all inside a very small package. This IC is designed
to be an small low power audio amplifier and is not too easily damaged.
Audio Oscillator And Audio Amplifier project is also available to you as a
free PDF download.
This Simple Power Supply
uses a transformer, diode, capacitor, resistor, LED, fuse and switch.
Simple power supplies like this are sometimes
called battery eliminators when they are made to output a particular voltage, 9 volts for example. If they are made adjustable, then a wide range of useful voltages can be produced from one simple power supply.