Camera exposure measuring circuit - uses photocell and operational amplifiers and exposure relative to amplification slope

摘要

The switching circuit is for adjusting exposure settings of an automatic camera according to the slope output characteristics of a photocell light measuring amplifier. The photocell (1) is connected between the inputs of an operational amplifier (2) and the output fedback via a potential divider (3, 4) with a diode (4) connected back to the inverting input of the operational amplifier (2). A second operational amplifier (5) is used for a second stage, also with a feedback loop to its inverting input.