The following diagram is the circuit diagram of basic monostable multivibrator based IC timer 555. This circuit uses only 4 electronic components that are a timer IC, two capacitors and a resistor.
A multivibrator is an electronic circuit used to implement a variety of simple two-state systems such as light emitting diodes, timers and flip-flops. The monostable multivibrator will create a condition: in which one of the states is stable, but the other is not—the circuit will flip into the unstable state for a determined period, but will eventually return to the stable state. Such a circuit is useful for creating a timing period of fixed duration in response to some external event. This circuit is also known as a one shot. A common application is in eliminating switch bounce.
R1 : read the explanation C1 : read the explanation C2 : 10nF IC1 : Timer IC LM555
- R1 and C1 determine length of output pulse where t = R1 x C1 and R1 is in ohms and C1 is in farads. You may determine the value of R1 and C1 to get the frequency needed.
- Pin 4 is the RESET. Leave it connected to power supply (+V) during normal operation. Bring pin 4 AND pin 2 low at the same time to reset timing cycle.