| 摘要 |
PURPOSE:To display relatively long-time proper exposure by providing a holding circuit which sends out an output for a time longer than the time required to charge a communication capacitor. CONSTITUTION:A proper exposure annunciator LED1 is connected in series to the exciting circuit consisting of a battery BT1, resistance R3, and transistor (TR) Q1. The base-emitter current path of the TRQ1 forms part of a charging circuit which charges the communication capacitor C2. When the discharging of the commutation capacitor C2 is completed as a result of a flash to be commutated, the base current of the TRQ1 turns on the TRQ1 to turn on the light emitting diode LED1, and proper exposure is displaced until the charging current can not hold the TRQ1 in the on state. Thus, said exciting circuit turns on the LED1 continuously for a long period (about 3sec). |
