momentary switch -> latching circuit?

I knew that I had heard of them being used somewhere else before - Volkswagen Beetles use the same setup toggle between heads and dims.

Google gives me this:
http://www.oldvolkshome.com/headrelay.pdf

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It is used on VW Beetles to toggle between low and high beams so it will handle a fair amount of current. It mechanically latches in alternating positions each time you push the switch connected to the terminal labeled "brown wire" in the drawing, with the other side of the switch connected to ground. The wire labeled white with black stripe would be connected to the +12V source thru an appropriate fuse. The coil is only energized when you push your switch.

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Originally Posted by pop058

What about a simple changeover relay. One pulse to change it one way and the next to change it back. One set of contacts are used to do what ever you require and the other set left vacant ??

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garden variety changeover relays wont work in this case, they only switch over while energised


hmm..... looks like its time to go to bed with a copy of the ashdowns book and hope the answer lies within

A little more googling tells me that the exact relay you are looking for is Relay "434" - 1C0 941 597. Apparently it's also used in Audi's.

Jaycar latching relay

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Originally Posted by Sprint

who said it was for foglights?

problem with a latching relay, is that to my understanding, is that once you trigger it, you need to kill the power to turn the relay off

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The VW headlight relay was used in Kombi's until at least 1979, that's probably the newest kombi I have dismantled in my youth. Visit your local pick-a-part style wrecker and look at all the early VW products on offer.

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Originally Posted by Blknight.aus

Jaycar latching relay

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Yeah, I took a look on Jaycar too and spotted that one.This is where it would be good to know what exactly you are trying to drive with this circuit. If it's a low current circuit, then there are more options available. On the other hand, if it's a high current application then the options are considerably narrowed down. Considering that you are using stock switches it could be heated seats, spotlights, fog lights, all which draw a decent number of amps. CAre to fill us in, or do we need to guess :p

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Originally Posted by mike_ie

Yeah, I took a look on Jaycar too and spotted that one.This is where it would be good to know what exactly you are trying to drive with this circuit. If it's a low current circuit, then there are more options available. On the other hand, if it's a high current application then the options are considerably narrowed down. Considering that you are using stock switches it could be heated seats, spotlights, fog lights, all which draw a decent number of amps. CAre to fill us in, or do we need to guess :p

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The other option is to use the Jaycar IC relay to drive another larger relay. Mind you, this starts to get a little trickier in the wiring, and you would probably need to enclose it all in a box -

Depending upon the application...:confused:

He's not saying because its one of those James Bond secret gadget missile kind of things....

Special Applications with SPDT Relays, Diagrams

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Originally Posted by VladTepes

He's not saying because its one of those James Bond secret gadget missile kind of things....

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Dunno, how much current does an ejector seat draw??? :confused: