LT1016 – LS74121 Voltage Controlled Pulse Width Generator/ Monostable Multivibrator



Mono-stable multivibrator circuit generates a fixed pulse width when receiving a trigger signal on its input. The pulse width of the output is fixed regardless of the input pulse duration/width. In practical application, the width of the output pulse is determined by choosing the right components values for certain application. In today’s digital electronics, mono-stable function can be easily implemented using micro controller. In many practical they’re more than enough, but many experimental works sometime need very specific function with high speed performance while maintaining its flexibility.

With this circuit schematic diagram, we can build a voltage controlled pulse width generator, so we can provide a flexible mono-stable multivibrator for doing many experiment in the lab. This circuit has two input, the voltage control for controlling the width of the output pulse, and the trigger input for triggering the output pulse generation. By adjusting the control voltage between 0 to 2.5V, we can adjust the width of the mono-stable multivibrator output between 0.05 to 2.5 uS. A full-scale calibration trimmer is provided to make sure this controlling range. This control voltage can be generated from a potentiometer (voltage divider) or from DAC (digital-to-analog converter) of a micro controller. Finally, this circuit provide two pulse output, the active high and active low (its inversion) for flexible usage.