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Subject: Re: Relay controlling electric doorstrike - kickback protection needed?
Date: Fri, 04 Oct 2002 10:24:24 GMT
NNTP-Posting-Date: Fri, 04 Oct 2002 06:24:24 EDT
Organization: Cox Communications
Thanks for getting back to me! Comments interspersed below...
> ohaya wrote:
> >I was wondering if anyone has had any experience with the 232DRIO? If
> >so, can you provide info about which relay is used?
> If you look at the manual on the site there is a picture of the PCB and
> they are obviously mechanical PCB mount relays and made by Omron - can't
> quite read a part number - look like GC5 series. I see no contact
> protection circuits on the board or any of the diagrams.
Are you talking about the picture (Fig. 4.1) on pg. 13 of the PDF
manual? When I download the PDF and display in it in Acrobat Reader,
the picture in the manual is really badly pixellated. In the picture
I'm looking at, Relay#1 looks like a crystal! You must have much better
eyes than I do :)!
> >If not, I was wondering, in general, if I should add any additional
> >circuitry between the relay and the doorstrike to protect the relay?
> With and ac supply an RC snubber across the contacts might extend their
> life a bit but their life is probably as long as the door strike mechanics
> without anyway.
That (i.e., that there wasn't any protection) was kind of my conclusion
from looking at the diagrams also.
If I'm understanding your comment above, then you're suggesting that no
additional circuitry should be needed between the relay and the
It's beeen awhile since I've worked with this stuff, but I thought that
a diode or something should be put in parallel with the output/contact
side of the relay to prevent inductive kickback?
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