The Sony Model ECM-33F
cardioid electret condenser microphone

This microphone was “newly designed” in 1977.

The battery saver switch.
 

Text and illustrations are from the SONY ECM-33F instruction manual,
Number 2-599-077-21 (2), downloadable at the bottom of this page.
Numerous spelling errors have been observed in the scanned text.

Download the ECM-33P Service Manual.
Courtesy of Torben Larsen.

Download the ECM-33F Owner’s instruction manual.
Twelve pages, one megabyte PDF