LM139 One Shot Multivibrator/Timer
One shot multivibrator circuit is also known as monostable multivibrator or timer. The function of such circuit is simply produce a pulse strobe with a fixed width, regardless of the pulse width of the triggering input. Below is the circuit’s schematic diagram of simple one shot multivibrator uses one section of an LM139 comparator. The width of the output pulse is set by C2/R4. Input trigger amplitude is set by R1/R2.