Some old tech

RichardO

Joined May 4, 2013
2,268
There were similar meters in the movie Apollo 13 (The Ron Howard version). The NASA engineers were trying to get the power consumption down to what was available on the damaged spacecraft. They caused a buzz every time the current demands were greater than was available.

From 1938:
ieeemilestones.ethw.org/images/6/6b/Weston-measuring-invisibles-OCR.pdf

upload_2018-8-24_14-24-34.png
 
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