In a message dated 4/22/99 2:44:21 PM Eastern Daylight Time,
randallyoung@earthlink.net writes:
> Your web page could easily be mis-interpreted to imply that an ordinary
> SPDT switch is adequate to control a pair of horns without a relay. I'm
> sure you realize this isn't true ...
Randall,
I didn't intend to give that impression. I specifically added a relay for the
new horns, as I assumed they would be drawing more current than the existing
horns. But, I did make one error in the second part -- which has now been
corrected -- in that I forgot to mention that the selector switch would need
to be rated to carry the full current of the existing horns. I don't think
there will be any problem with this, as the horn button switch is not exactly
a high current type switch, yet it lasts for a long time, and it actually
switches the horn circuit live. The selector switch will almost always switch
a dry load, which is very easy on the contacts.
If you can point me to where I gave the wrong impression, I will immediately
correct it. Sometimes the author can be too close to the subject to see this
sort of things clearly.
> My suggestion for people without original horn relays (like my TR3A) would
> be to add one. However, I wouldn't use a 'driving light' relay, since
> horns (especially older ones) are a nasty inductive load with a high peak
> current (when the points are closed). Any auto store should be able to
> order a 'universal' horn relay, or a creative soul should be able to find
> one on a junked car.
I have been using one of them for several years now for the horn, with no
problem. For the new horn, the relay will be operating a motor (air
compressor), which won't have quite the inductive kickback of the horn.
You're right, the horns do have a nasty bite when switched off.
> Also, I believe Radio Shack sells fairly "automotive" looking SPDT
> switches, both rocker and toggle, and is pretty ubiquitous, at least in
the
> US.
You may be right, it's been a while since I looked for one there. I seem to
recall that I didn't find one I liked the last time I did, but it's still
worth a try.
> Other than that, Nice Page !
Thanks.
Dan Masters,
Alcoa, TN
'71 TR6---------3000mile/year driver, fully restored
'71 TR6---------undergoing full restoration and Ford 5.0 V8 insertion - see:
http://members.aol.com/danmas/
'74 MGBGT---3000mile/year driver, original condition - slated for a V8 soon
'68 MGBGT---organ donor for the '74
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