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 Posted: 03-23-2005 12:44 am
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John Kimbrough
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Not too long ago, after reading about the benefits on the JHPS message board, I decided to put relays in to control my headlights.  This both delivers appropriate current to the new, better headlights, and reduces the current that flows through the delicate, expensive JH instrument switches.  If you have an interest in doing this little project, I have shared my experience on my web site, below

John's Jensen Healey Web Page

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 Posted: 03-23-2005 08:25 am
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Glen
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Location: Placerville, California USA
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What does a relay do that allows it to reduce the current that flows through the delicate, expensive JH instrument switches?  How does it work?

 

#19667

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 Posted: 03-23-2005 09:53 pm
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John Kimbrough
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Glen, in stock installations all the current that goes to operate the headlights goes through the delicate headlight switch and dip switch in the cockpit.  What a relay does is isolate the headlight and dip switches from this full (high) current.  It takes just a little current (going throught the headlight and dip switches) to activate the relay, and then the relay supplies the full (high) current to the headlights.

John's Jensen Healey Web Page

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 Posted: 03-23-2005 11:55 pm
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Mark Rosenbaum
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To amplify John's comment just a little, a relay consists of two elements: (a) a set of switch contacts capable of carrying a "high" current, and (b) an electromagnet that, when energized by a "low" current, causes the switch contacts to close.  What a "low" current is, or a "high" one, depends on the application.

As John notes, the wiring that originally went to power the headlights would be moved to instead operate the relay's electromagnet.  This would reduce the electrical load on the lights switches by a factor of about 300.  A new wire, perhaps with an inline fuse, would run from the battery to one of the switch contacts, and the headlight would be wired to the other switch contact.

There are all sorts of different relay types available, so anyone not too familiar with car wiring, who wants to implement a system like the one John describes on his web page, would be well advised to follow his plan carefully.

Last edited on 03-23-2005 11:57 pm by Mark Rosenbaum

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