Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
An oscillator is a positive feedback circuit which produces oscillations at its output. These oscillations may be sinusoidal or non-sinusoidal like square wave, triangular wave, spikes etc.
For more details search for "Barkhausens Criteria" for sustained oscillations in a positive feedback circuit and various oscillators like
1) Colpitts Oscillator
2) Hartley Oscillator
3) Wein Bridge Oscilaltor
4) Astabale Multivibrator
5) UJT Relaxation oscillator