As shown in Figure II F003 is versatile photographic constituent operational amplifier amplifying automatic timer circuit. Operational amplifier A1 composition integrator
operational amplifier A2 composed of comparators. 2CR silicon photocell voltage is generated by the integrator input signal V1, the signal input from the pin , Al output voltage with the reference voltage to the comparator comparison. When the output voltage is equal to the upper limit threshold voltage comparator Ems, A2 comparator output is high, the transistor VT conduction, relay, lamp, and the end of exposure, exposure time so as to achieve automatic control purposes. Ems by a 10k potentiometer setting, the exposure time T = R1C1Ems / V1. S switch to automatic, manual switch. AN integrator reset button for the switch.