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Hi Max- (to list)<br>
<br>
A relay is essentially an electromagnet that operates a set of
switch contacts. <br>
<br>
Think of the electromagnet as similar to a spool of thread with a
dowel running through the center. The thread is fine wire. The
dowel is made of ferrous metal. At one end of the dowel, is part of
an armature that is pivoted to act as a lever. The other end of the
lever is insulated in some way, and acts upon the set of switch
contacts. <br>
<br>
When power is applied to the electromagnet, it attracts the nearby
part of the armature, exerting leverage to operate the switch
contacts. <br>
<br>
Relays are typically used for switching of signal paths (telephone
switching) and for switching of unlike power (power relays). The
physical construction of relays varies widely, from small ones
mounted on circuit boards, to large ones mounted on racks.<br>
<br>
In the door opener, the relay may be designed to take logic-level
power (5 volts DC) and operate a set of switching contacts that
handle a higher level of power from the door strike power supply to
the door strike itself (typically 24 volts AC or DC). This is
probably a small relay, an inch by a half-inch or so, but relays can
get quite large depending on their application.<br>
<br>
If you want to see more relays in one place than you're ever going
to see in real life, keyword search "strowger switch", preferably on
a video site so you get to see them operating. <br>
<br>
-G.<br>
<br>
<br>
=====<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 13-11-24-Sun 8:17 PM, Max Klein
wrote:<br>
</div>
<blockquote
cite="mid:CAKbmofhwoK8QPpaM=XQbzJdvMeYW05YxywzVuu2MD-VcTd1OQw@mail.gmail.com"
type="cite">
<div dir="ltr">Only last night I got the keypad running again, and
was trying to insultate the wires to improve its uptime.<br>
<br>
So I coated two connections between the rasberry pi and the
relay which is attached to the door. After coating, it seemed
like I somehow failed these connections, because the software
exited normally (opendoor.py was still being called and sent
success messages), but the door was not opening. I tried to
unglue them, but when i was taking off the glue, I disconnected
one of the wires that was at this 3-way junction. Then I
resoldered the wires but to no avail.<br>
<br>
<div>So everything is totally broken now. Can you help with a
multimeter and a solder gun Monday to hunt this down? I don't
know how to test if there is current at point, nor why the two
wires would split coming of the rpi, and then both go to same
relay. BTW what's a relay (i've only heard the term)? <br>
<br>
</div>
<div>Please tutor me in the ways of righteousness,<br>
</div>
<div>notconfusing<br>
7074787023<br>
</div>
</div>
<br>
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