Monostable Trigger

Publishing Venue

IBM

Related People

Brode, GD: AUTHOR [+2][-]

Ward, TD: AUTHOR

Abstract

The transistor monostable trigger, using complementary symmetry, reduces power dissipation during the quiescent state as both transistors then are non-conductive.

Monostable Trigger

The transistor monostable trigger, using complementary symmetry, reduces power dissipation during the quiescent state as both transistors then are non- conductive.

During quiescence, the NPN transistor 10 is back-biased, due to current flow from -V(E1) through the diode 11, and the resistor 12 to the more negative point - V(B1). The PNP transistor 13 is back-biased by current flow from +V1 through the timing resistor 14, the diode 15 and the resistor 16 to -V2. When a positive pulse is applied to the input, transistor 10 becomes conductive and the collector voltage drops. Since the timing capacitor 17 cannot change charge instantaneously, this voltage drop causes the diode 15 to be back-biased, allowing transistor 13 to become conductive. Its collector rises to approximately V(E2).

Immediately the timing capacitor 17 begins to charge toward V(1), at a rate determined by the timing resistor 14 and the capacitor 17. As this voltage becomes positive enough to forwardly bias the diode 15, transistor 13 becomes non-conductive. Its collector voltage drops, and transistor 10 is in turn cut off. The output of the circuit is taken from the collector of transistor 13 and provides an output gate of a predetermined time duration.

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