Duff horn circuit

[wade.edwards]

Finishing cable hookups on a new, old school, single strand wire layup. No cloth.

Having a problem with the horn circuit, in part because I don’t understand how it should operate. Have done plenty of research and experimentation.

My biggest question is regarding a ground for the horn button. This button style has no ground terminal and yet the wiring diagram says it should be earthed to the frame. That would be difficult with rubber handlebar holders.

-should there be a ground wire to the frame?

I have swapped two new horns in and out and both equally work only VERY intermittently and mostly not at all.
Have had it sound while not mounted but immediately upon bolting it to the mount, there is NO SOUND. It will have a very light pulsing movement but no sound.

There is one hot cable from the charged battery to a horn terminal and one lead from the push button.


-As long as the button lead is not connected to the horn, it is cold. Once both leads are connected to the horn then both wires are hot.
-Is this correct? Still trying to figure out if the button is supposed to be hot.


It shouldn’t be this complicated.

[simon.holyfield]

A 'very light pulsing movement' suggests the horn is not adjusted properly. The horn circuit is very simple - one terminal at the horn receives a six volt supply, the other goes to earth. I wouldn't be surprised if the horn button finds its earth through the clutch and throttle cables when the handlebars are fitted with the rubber mounts.

What sort of horn is it? It looks like an Altette? Perhaps you can show us a picture of the front. Older Altette horns have an adjusting screw underneath the big acorn nut. If you back that out a little bit, the diaphragm will move a bit more allowing the points within the horn to open and the whole diaphragm to vibrate. Try it off the bike though I found they behave differently between bench and bike! It may be that your earth is poor and you don't have 6V across the horn terminals.

This blog post might help you:

https://ariel-square-four.blogspot.com/ ... ltette?m=0

[nevhunter]

We have 2 discussions on this matter at the same time?. Get the Horn working perfectly before fitting it. I have had them with short-circuited windings which will draw a HUGE current. This circuit is NOT fuse protected and is live anytime the battery is connected so be extra careful with the wiring insulation condition. Nev

[ian williams]

one thing to think about is that the drawing pictured in this thread is showing the horn connected to the positive terminal which may be right or wrong depending on how the bike is wired up .
check to see if you have positive or negative earth configuration on your bike ..
some horns have a little screw for adjustment but im afraid i dont know anything much about your type of horn to tell either way .
a lot of the time you need the bracket of horn earthed in order for it to work .
cheers , ian