voltage drop detector

83 This circuit will generate an output pulse whenever the input voltage drops by more than 0.6 volt. Oper- ation of the circuit is very simple. As long as the input voltage remains constant or increases, the voltages at points A and B will be equal to the input voltage minus 0.6 V (due to the voltage drop across D1 and D2). In this condition transistor T1 will be turned off. If the input voltage drops, the voltage at point B will drop accordingly. The voltage at point A, however, will remain un- voltage drop detector 80554 changed because C1 will be charged. When the difference in voltage between points A and B becomes greater than 0.6 V (in other words, the input voltage will have dropped by 0.6 V), T1 turns on causing C1 to discharge through R1 — generating an output pulse.