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DC relay coil

Started by Bob Engelhardt October 19, 2021
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
On 10/19/2021 11:08 AM, Bob Engelhardt wrote:
> 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
If the designers marked it, probably would be good to follow that.
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.
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.
On 10/19/2021 4:26 PM, Sjouke Burry wrote:
> 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. >
They may use that package to make units with the diode.
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.