• Print
• Login

Monostable Pulse Generator

<^< Astable Pulse Generator | Course Index | Assessment: Active Circuits >^>

Click here to download TINA circuit file

The monostable pulse generator (also known as a "one-shot") produces a single pulse rather than a continuous train of pulses. The monostable timing period (i.e. the time for which the output is high) is initiated by a falling edge trigger pulse applied to the trigger input (pin-2).

When this falling edge trigger pulse is received and falls below one third of the supply voltage, the output of IC₂ goes high and the bistable will be placed in the set state. The output of the bistable then goes low, TR₁ is placed in the off (non-conducting) state and the output voltage (pin-3) goes high.

The capacitor, C₁, then charges through the series resistor, R₁, until the voltage at the threshold input reaches two thirds of the supply voltage (V_CC). At this point, the output of the upper comparator changes state and the bistable is reset. The output then goes high, TR₁ is driven into conduction and the final output goes low. The device then remains in the inactive state until another falling trigger pulse is received.

The output waveform has the following properties:

Where t is in seconds, C₁ is in Farads and R₁ is in ohms.

<^< Astable Pulse Generator | Course index | Assessment: Active Circuits >^>