Level and frequency measuring recorder

摘要

An audio-frequency generator applies signals to a unit under test. The output of the tested unit is applied selectively through either an amplifier having a linear or a logarithmic characteristic to a push-pull output stage driving a rotary coil measuring instrument. The latter drives a recording stylus. An electronically controlled paper drive is coupled to the wiper arm of a potentiometer. The voltage picked up by the wiper arm is applied to the audio-frequency generator to control the frequency thereof.