DC relay coil

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Bob Engelhardt

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Oct 19, 2021, 11:08:33 AM10/19/21
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I have a DC relay with the coil connections marked "+" & "-". Does it
matter? The relay operates with either polarity so there is no internal
flyback diode. It's a 24v, 33ma coil for those who want to know.

Thanks, Bob

Tom Biasi

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Oct 19, 2021, 11:23:42 AM10/19/21
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If the designers marked it, probably would be good to follow that.

Bob Engelhardt

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Oct 19, 2021, 3:34:06 PM10/19/21
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Yeah ... I guess what I was really wondering was why they would do that.

Sjouke Burry

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Oct 19, 2021, 4:28:05 PM10/19/21
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On 19.10.21 21:33, Bob Engelhardt wrote:
> Yeah ... I guess what I was really wondering was why they would do that.
>
>> If the designers marked it, probably would be good to follow that.
>
they should do that if a built-in diode is present.
Also, the plus and minus identify the coil pins.

Tom Biasi

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Oct 19, 2021, 4:31:47 PM10/19/21
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They may use that package to make units with the diode.

Bob Engelhardt

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Oct 21, 2021, 9:55:12 AM10/21/21
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I Googled it (like I should have in the first place). There are a
couple of reasons that a DC relay may be polarized:
- internal flyback diode (as mentioned)
- an internal LED indicator
- a permanent magnet used to augment the mag field
- in a latching relay

My relay does have a LED indicator, so that's what I'm assuming is the
reason for my polarization. And not a permanent magnet.
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