Control of sound diaphragm of photo sound recorder - involves circuit incorporating two charge capacitors used alternately for control

摘要

The apparatus is for controlling the sound diaphragm of a photo sound recording instrument, so that sound recordings can be transferred to film from e.g. magnetic tapes while the film is run in either direction. The arrangement has the input signal passed to a pre-amplifier which amplifies weak signals more than strong signals. From a further amplifier and rectifier the signal reaches a set of charge capacitors through diodes and resistors. The load voltage of the capacitors is limited by a Zener diode incorporated between the rectifier and the other diodes. The capacitors are alternately short circuited by electronic switches whose control electrodes are connected to an oscillator the load voltage of the non short-circuited capacitor being used to control the sound diaphragm.