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Any electrical engineers on MacNN? I have a relay question...
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Dedicated MacNNer
Join Date: Jul 2002
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Okay, so I need this part:
http://www.nteinc.com/relay_web/pdf/R47.pdf
But NTE is backordered by about 6 months. I've tried ordering from several different companies (nobody seems to carry stock?) and they all tell me it's backordered. I can't wait 6 months. We're ordering new laptops and I need to get the laptop carts working again. Can anyone here recommend a compatible part? In fact, I think I could use a relay with slightly more lenience. This is the third relay to die on these carts. I'm wondering if the power draw is too high for these relays, but I'm not an engineer and know next to nothing about amperage and watt not.
See what I did there? lol.
Anyway, thanks for the help.
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Administrator  Join Date: Apr 2001
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What does the relay do? Does it stay energized all day long, or only for short periods? I'm guessing it stays energized pretty much 24/7, or at least for a whole work day. The thing with relays is that if the coil isn't designed for being energized on the long term, it's going to burn up eventually. The more appropriate part for this application would be a latching relay. Unless the relay is only going bad on one cart and a number of others are working fine, it's a design problem.
But that specific relay shouldn't be a huge problem to find, nor would a suitable substitute. As seanc noted, you could check with those 4 (or other) vendors for a relay that meets the same or higher standards and be just fine. If it wires in with a socket rather than individual slide-on connectors, that may limit your use of alternatives, but probably not by much.
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Glenn -----OTR/L, MOT, Tx
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Originally Posted by seanc 
You didn't specify which one you wanted.
I need the NTE one, or something compatible. I was asking if the OMRON one was compatible because I've been having a dickens of a time finding a someone who has any NTE's in stock. They've been on backorder from NTE for several months, and NTE tells me it's going to be several months more.
Originally Posted by seanc
Thanks for taking the time to reply. I've been doing that all day, and I can't seem to get anyone who can tell me, so I thought I'd ask here. Tried Mouser, Newark, WholsaleElectronics, and Tycho. I'll give DigiKey a call. NTE is back ordered on this particular relay by about six months and none of the distributors seem to have it in stock. Just talked to Newark about 10 minutes ago and same deal. I'll give RS Components a call and confirm they have it in stock.
Originally Posted by ghporter
What does the relay do? Does it stay energized all day long, or only for short periods? I'm guessing it stays energized pretty much 24/7, or at least for a whole work day. The thing with relays is that if the coil isn't designed for being energized on the long term, it's going to burn up eventually. The more appropriate part for this application would be a latching relay. Unless the relay is only going bad on one cart and a number of others are working fine, it's a design problem.
But that specific relay shouldn't be a huge problem to find, nor would a suitable substitute. As seanc noted, you could check with those 4 (or other) vendors for a relay that meets the same or higher standards and be just fine. If it wires in with a socket rather than individual slide-on connectors, that may limit your use of alternatives, but probably not by much.
Yeah, all day long. I've always been concerned about these carts because from day one, simply turning the cart on jettisons a few sparks from the switch, which says to me it's either drawing too much current, or there aren't adequate resistors. Our newest Bretford cart (they were here before I started working, so I didn't have a say) doesn't do that and hasn't lost a relay yet. It's a little different in that there's a short delay between powering on and switching between the top and lower racks of laptops. No sparks.
The reason I'm so keen on getting these relays is that Bretford wants to charge $600 for a new timer/PSU assembly. $600 for a whole new assembly when it would cost me $12 to replace the part that's actually failing. Except, if they keep failing on me like this and continue to be this elusive, I may just have to break down and buy the stupid things.
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Originally Posted by Warhaven
I need the NTE one, or something compatible. I was asking if the OMRON one was compatible because I've been having a dickens of a time finding a someone who has any NTE's in stock. They've been on backorder from NTE for several months, and NTE tells me it's going to be several months more.
Ah, but the sheet you attached has 4 different part codes. Do you have a specific part code?
R47−1A15−24
R47−1A15−120
R47−5A15−24
R47−5A15−120
?
NTE Electronics Inc should be the manufacturer of the relay. Newark (Farnell in the UK) are saying they have 17 of the R47−1A15−120 on their website as do RS Electronics (23) (not releated to RS Components as far as I am aware).
Farnell are usually good about keeping stock levels up to date, so I'd be surprised if Newark didn't have that part.
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Thanks for the help. And yes, it's the R47−5A15−120. 5-pin version.
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