Time limiter for automatic exposure control circuit - shines light on photocell after given time lapse from threshold trigger circuit fed by timing circuit

摘要

The time limiter for automatic exposure control circuit shines a light on the photocell after a given time lapse. The additional light comes from a light source, pref. a l.e.d., at the output of threshold-trigger circuit whose input is taken from a timing circuit. This auxiliary timing circuit is reset at the same time as the main exposure timing circuit. Its condenser is charged through a fixed resistor of suitable value with different values for daylight and flash photography. The change from the daylight to the (smaller) flash-photography resistor is pref. made automatically when the flash unit is set in place.