From: Allen Mulvey <allen@amulvey.com>
To: 'Microcontroller discussion list - Public.' <piclist@mit.edu>
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Date: Sat, 18 Jan 2020 14:07:34 -0800
Subject: RE: [CAUTION: Failed DKIM Test][EE] Magnetic lock
Thread-Topic: [CAUTION: Failed DKIM Test][EE] Magnetic lock
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Is there a small plunger connected to a microswitch which
detects the physical contact?

Allen
PS: I use a pair of 600 pounders on my front door with
magnetic strikes everywhere else.

-----Original Message-----
From: piclist-bounces@mit.edu
[mailto:piclist-bounces@mit.edu] On Behalf Of David C Brown
Sent: Saturday, January 18, 2020 4:27 PM
To: Microcontroller discussion list - Public.
Subject: [CAUTION: Failed DKIM Test][EE] Magnetic lock

I have just purchased a magnetic lock for my workshop so
that I can
dispense with using metal tokens to free the door.

The lock consists of an armature plate which bolts to the
door and an
electromagnet which, when energised, grabs the armature with
a force of
several hundred pounds.

I splashed out an extra fiver for the "monitored" version
which lights an
LED anf operates a relay when the device detects that the
armature is held
by the magnet.  But how does it detect the locked condition?
Does the
current in the magnet increase when something is attracted
by it?  Or what?
__________________________________________
David C Brown
43 Bings Road
Whaley Bridge
High Peak                           Phone: 01663 733236
Derbyshire                eMail: dcb.home@gmail.com
SK23 7ND          web: www.bings-knowle.co.uk/dcb
<http://www.jb.man.ac.uk/~dcb>



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