From: email@example.com (Ed Hahn) Organization: The MITRE Corporation Date: 27 Jun 96 12:56:53 References: 1 Followups: 1
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In article <airliners.1996.1046@ohare.Chicago.COM> Al Hrovat <firstname.lastname@example.org> writes: ah> I understand that modern aircraft use a magnetic sensor called a ah> proximity switch to determine the position of landing gear, doors, ah> etc. Does anyone know why this arrangement is used instead of a ah> simple mechanical switch? Are the magnetic pick-offs more ah> reliable than a simple switch? The prox switches (in theory) are much more reliable than the older mechanical switches, as they are sealed from the environment and need no adjustment to ensure proper operation. (As opposed to a mechnical switch which must be adjusted to ensure that the switch reads "closed" at the appropriate location in the mechnical travel, depending on the application.) The principle of operation is very simple; the magnetic pickup can sense an change in inductive impedance when the appropriate metal is touching the surface over the pickup. This method is actually quite analagous to the turn-lane sensor loops which are buried in the roadway and tell the traffic light controller that a car is at the intersection. ed -------- Ed Hahn | email@example.com | (703) 883-5988 -------- The above comment reflects the opinions of the author, and does not constitute endorsement or implied warranty by the MITRE Corporation. Really, I wouldn't kid you about a thing like this.