. The Bell System technical journal . line is mo\ed up and overtiie turning point. AVithout capacitor C in the circuit, the operatingpoint would move to b with the resultant rapid change in voltage andcurrent. However, a capacitor has in effect voltage inertia; this isequi\-alent to saying that a capacitor is a short-circuit to a voltagechange. Both the capacitance and the rate of change of voltage areassumed high. Thus at the turning point the capacitor effecti\elyshort-circuits the emitter and the operating point snaps along dottedline (1) to intersect the characteristic. This point is ciuas
. The Bell System technical journal . line is mo\ed up and overtiie turning point. AVithout capacitor C in the circuit, the operatingpoint would move to b with the resultant rapid change in voltage andcurrent. However, a capacitor has in effect voltage inertia; this isequi\-alent to saying that a capacitor is a short-circuit to a voltagechange. Both the capacitance and the rate of change of voltage areassumed high. Thus at the turning point the capacitor effecti\elyshort-circuits the emitter and the operating point snaps along dottedline (1) to intersect the characteristic. This point is ciuasi-stable andtiie capacitor is discharged along line (2) to the second turning pointwhere the emitter is again effectively short-circuited and the operatingpoint snaps along (3) to intersect the Region I portion of the character-istic. This point is also quasi-stable and the operating point movesslowly up to the initial or dc stable operating point. A single triggerthus causes a complete cycle of operation. The emitter current shifts. Fig. 6—Bistable circuit showing trigger sensitivity, A. 1216 THE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1952 rapidly to a high value of current, falls relatively slowly to an inter-mediate value, then shifts rapidly to a small negative value and finallyreturns slowly to the original value. The emitter current and voltageare sketched in Fig. 8. It is a so-called single-shot circuit. Alternatelythe rest or do stable point can be chosen to be in Region III, at highcurrent, by choice of positive instead of negative bias F„ . Practicalconsiderations as ease in triggering and average power consumptionusually indicate a preference for the Region I dc stable point.
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