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Relays SPDT to SPST

Posted: Mon Mar 10, 2014 3:13 am
by GordonBH
I am having real issues sourcing Single Pole Single Throw relays with diodes in the UK. I can easily get SP Double throws with diodes (e.g. headlight relay) but not singles. I can use the SPDT for the fan relay as there is no wire running to the #87a pin so it would act like a SPST.

BUT, my Starter relay (07 SB) is a Single Throw with 2 x #87 pins and 5 wires.

My question is: on an SPDT can I run the wire that goes to the #87a middle pin to the #87 pin - then firing both on relay energising?

The wire I'm thinking of moving is the #58 "Fuel shut-off - Starter" currently sitting on the middle #87. I believe both 87's sit in open circuit at rest until the relay is energised when they both close.

My idea is that with the #58 and #87 wire (co-incidentally wired to a #87 relay pin) both wired into the #87 on the Double Throw relay that would do the trick. But, "Sometimes a little knowledge is a dangerous thing"

:hmmmm:

Re: Relays SPDT to SPST

Posted: Tue Mar 11, 2014 9:02 pm
by Ric
As you probably know with what you've presented so far… The diode between 85 and +86 isn't your concern as that's only the coil that engages the relay. 30 is the common terminal, And 87 and 87a are the two normally Open sets of contacts. You likely already know this… but with the way you've worded this post… I'd say you are correct. When the coil is energized… both #87 terminals make a closed circuit. Just like you posted.

Re: Relays SPDT to SPST

Posted: Tue Mar 11, 2014 9:15 pm
by Iron Maiden
Gordon- I have no idea what you are asking but I might have a solution...... Do the states have the relay you need? If so can someone (me) ship a couple to you or another possibility is that there are several v8 riders visiting for bike week from across the pond, maybe they can pack a few in their luggage??? Just A thought. :usa:

Re: Relays SPDT to SPST

Posted: Wed Mar 12, 2014 3:31 am
by GordonBH
Hi there,

Hey Ric, thanks for the confirmation, I'll go ahead on that basis.

Thanks Sue for the kind offer, in the short term I'll re-work some Double Throws. I just wish I could get to bike week and meet some of you guys, maybe next year.

Gordon
:england: