summary
● An oscillator is a nonrotating device for producing alternating current.
● The output of an oscillator can be sinusoidal, rectangular, or sawtooth.
● The main requirement of an oscillator is that the output be uniform and not vary in frequency or amplitude.
● A tank circuit is formed when a capacitor is con- nected in parallel with an inductor.
● A tank circuit oscillates when an external voltage source is applied.
● The oscillations of a tank circuit are dampened by the resistance of the circuit.
● For a tank circuit to maintain oscillation, positive feedback is required.
● An oscillator has three basic parts: a frequency- determining device, an amplifier, and a feedback circuit.
● The three basic types of sinusoidal oscillators are LC oscillators, crystal oscillators, and RC oscillators.
● The three basic types of LC oscillators are the Hartley, the Colpitts, and the Clapp.
● Crystal oscillators provide more stability than LC oscillators.
● RC oscillators use resistance-capacitance networks to determine the oscillator frequency.
● Nonsinusoidal oscillators do not produce a sine-wave output.
● Nonsinusoidal oscillator outputs include square, sawtooth, rectangular, and triangular waveforms and combinations of two waveforms.
● A relaxation oscillator is the basis of all nonsinusoidal oscillators.
● A relaxation oscillator stores energy in a reactive component during one part of the oscillation cycle.
● Examples of relaxation oscillators are blocking oscillators and multivibrators.