A simple oscillator

A simple oscillator using a relay and a capacitor

In simple meaning an oscillator is a device which does not remain in a steady state, but oscillates between two states at a certain frequency.In this oscillator I have used only one capacitor & a relay.

Brief about relay:
Symbol of a relay is shown in the diagram.
In simple words a relay is like a simple switch but the relay is controlled by passing current through its coil.Most of the relay has two terminals called NO & NC. NO stands for Normal Open.
As the name suggests when the current is not passing through the relay it remains open. NC stands for Normal Closed. It remains closed in its steady condition. Now when we pass a certain amount of current through it, it is actuated & NO becomes closed & NC becomes open.
Thus relay is a switch which can be triggered by passing a certain amount of current through it.

Circuit Diagram

Take a look at the circuit diagram of the oscillator.
When the battery is connected, at that instant, Capacitor being shorted by NC terminals, capacitor acts as a short circuit and lets the current to pass through it. Therefore the current passes through the relay so it is actuated and NC becomes open. Now capacitor starts charging so for sometime it lets the current flow due to its charging characteristics. After it is charged it blocks the current so the relay comes in its initial state. So again NC terminals discharge the capacitor & the whole process continues & the switch in relay oscillates.
I have tried it & it works fine.
Although there are oscillators which uses transistors & are more accurate than this one, this type of oscillator can be used where we need some type of LED blinking arrangement or something like that.