3829850 is referenced by 147 patents and cites 7 patents.

A capacitive proximity detector protects against injury, damage or unauthorized entry into a protected area. It comprises an unbalanced capacitive bridge including an antenna or sensor which produces an output proportional to the capacitance of the antenna to ground. A change in capacitance is detected and the resulting signal is applied to a pair of 'windows' having maximum and minimum values which, if exceeded, operate a pair of relays and produce a suitable visual indication. Many fail-safe and other safety features are provided in the detector.

Title
Proximity detector
Application Number
05/209,333
Publication Number
3829850
Application Date
December 17, 1971
Publication Date
August 13, 1974
Inventor
Guetersloh John W
Agent
LeBlanc & Shur
Assignee
Tyco Laboratories
IPC
G08b 13/00
H03K 17/955
H03K 17/94
G08B 13/22
G08B 13/26
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