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MG Midget and Sprite Technical - Horn relay help

Can someone help direct me to someplace I could see the wiring layout for wiring in a relay for my horns?
I have a mk2 sprite positive ground with dual horns.
Would like to know what parts I will need and a layout on how to do it. Searched some but could not find any diagrams.
Thanks
Mike
MK Mike

for the original horns - or additional/new horns ?
Dean Smith ('73 RWA)

replace the horns with a relay use the relay to switch the horns on new cable wired via a fuse to the battery!
Mick - nearly ready to paint

As much as I would hate anyone to think we old fogeys are trying to control or stagnate thinking (Oh soddit, sorry wrong place to preach!) this is basically how I would do it.

The switched output from the ignition circuit comes off the fused supply then is switched by the relay control circuit 86-85 to earth at the horn push, little amperage required so the horn terminals don't carry heavy current loads any more.

The main power to the horn is via terminal 30 direct off a battery live source, preferably with soldered joints to obtain the least resistance and thus the lowest power loss possible.

The fuse is optional but probably advisable.

Output from 87 feeds the horn circuit(s) and then direct to earth. No current flows through the horn until 86-85 pull in the relay solenoid and make it all go "beep".

HTH


Bill

Bill
Thanks, exactly what I was looking for. could not figure out the numbers on the relay. One question, in the diagram it's NEG ground. It should be reversed for "our" positive ground cars? correct? Just want to make sure here.
Mike
MK Mike

I really don't know but I would think that as long as there is no diode in the relay it ought to work the same under either earth setup

A test bench set up first to try the concept ought not be too difficult

But fear not there will be knowlegable folks along any minute that have the real answer at their fingertips

When I rebuilt my car I fitted an alternator and re-wired it negative earth from the outset.
Bill

Bill
So you left the sacred order of the Positive Earth Club??
Mike
MK Mike

Yes I succumbed to the lure of electronic ignition (20k miles, no attention yet except removing damp from inside dizzy cap)
A stereo that could play CDs and tapes (Old fashioned Bosch twin unit device, now gone to stereo boneyard in the sky) and Halogen headlights that actually reach upto and almost around the next corner down the road...

Fitting the Alternator using a spare bracket off a BMC Mini was easy and so was the rewiring of the charging system.
Bill


Pos or Neg earth makes no difference, the power still actives the coil which trips the switch, here's a little film of a relay working (scroll down) http://www.kpsec.freeuk.com/components/relay.htm

Andy
a borris

nice handy link there Andy
Bill

This thread was discussed between 28/04/2008 and 29/04/2008

MG Midget and Sprite Technical index

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