Beckman Helipot Potentiometer Model SA1400A - bb59e2dd8d27cd60ccdf7694d266c252
Summary
Black finished cylindrical casing with three copper electrodes in a line next to product inscription; nickel knob is raised above the cylinder; outer dial goes from 0-15 (but only three digits are visible through its viewing slit); outer dial value changes when inner dial (0-100) is manually rotated 360 degrees; knob handle is black plastic. Potentiometers are used to measure electromotive force (emf) by balancing it with a known emf. The concept was first developed in 1841 by J. C. Poggendorff and improved throughout the 19th century by Latimer Clark and J. A. Fleming.
Source
Science History Institute
Copyright info
Public Domain