13-04-2013, 04:30 PM
IC 555 TIMER-MONOSTABLE OPERATION CIRCUIT
AIM:
To generate a pulse using Monostable Multivibrator by using IC555
THEORY:
A Monostable Multivibrator, often called a one-shot Multivibrator, is a pulsegenerating
circuit in which the duration of the pulse is determined by the RC network
connected externally to the 555 timer. In a stable or standby mode the output of the circuit is
approximately Zero or at logic-low level. When an external trigger pulse is obtained, the
output is forced to go high ( VCC). The time for which the output remains high is
determined by the external RC network connected to the timer. At the end of the timing
interval, the output automatically reverts back to its logic-low stable state. The output stays
low until the trigger pulse is again applied. Then the cycle repeats. The Monostable circuit
has only one stable state (output low), hence the name monostable. Normally the output of
the Monostable Multivibrator is low.
Procedure:
1. Connect the circuit as shown in the circuit diagram.
2. Apply Negative triggering pulses at pin 2 of frequency 1 KHz.
3. Observe the output waveform and measure the pulse duration.
4. Theoretically calculate the pulse duration as Thigh=1.1. RAC
5. Compare it with experimental values.