A Transmission-Measuring System Utilizing a Graphic Recording Meter
W. Lindsay · Journal of the Society of Motion Picture Engineers · 1937
The design of a transmission-measuring system utilizing an Esterline Angus recording meter is described. A circuit was developed requiring a special triode exhibiting a logarithmic relation between change of grid bias and plate current. The audio oscillator is a commercial type to which has been added a synchronous motor drive geared to the frequency dial. For the amplifier-rectifier, required to operate the 5-ma. recording meter, use is made of a push-pull class A amplifier terminated by a full-wave, approximately square-law tube rectifier, the d-c. output of the latter being connected to the recording meter. — The paper concludes with a discussion of the various applications to which the system may be put.