The 555 timer is a versatile and widely used device because it can be configured in 2 different modes as either a monostable multivibrator (one-shot) or as an astable multivibrator (oscillator). An astable multivibrator has no stable states and therefore changes back and forth (oscillates) between two unstable states without any external triggering.
Setting up the 555 timer as an oscillator
The external components R1, R2 and C1 form the timing network that sets the frequency of the oscillation.
The 0.01�F capacitor C2 connected to the control (CONT) input is strictly for decoupling and has no effect on the operation. |
