Capacitor charge indicator in an electronic photoflash

摘要

A glow lamp for indicating charged readiness of a flash apparatus is provided with a predetermined burning voltage corresponding to a specific charge voltage of the storage capacitor for the flash circuit, and the ignition voltage for the glow lamp is applied as periodic ignition pulses derived from voltage pulses occurring on periodic switching of the converter. The result is a more accurate response of the glow lamp to the desired charge value of the storage capacitor than is obtained by using the ignition voltage of the glow lamp as a threshold value.