Horn

[Alex Goodhart]

Horn

[Alex Goodhart]

Just

[Jacques Lefriant]

Alex it depends what it sounds like. you might have discovered a unique signature so we know when you are coming. I prefer air horns much nicer sound.
j

[Alex Goodhart]

Yes I like a

[Craig Richter]

I love my 6v horns on 12v. Even truckers on the Autobahn can hear us!

[Ned Gorski]

seeing as we are talking about horns.. the horns on my 55 cab looked all road rashed up when i found the car, so i figured rebuild them like the rest of the car..i sat down on the work bench and opened them up.. When i separated the two halves i heard a quick hiss . then smelt what smelled like a new text book ( cheesy odor ) The inside of the horn was super gloss black and looked as if they were just built.. and on the inside of horn was one perfect thumb print. over time the oils from the print reacted with the paint so the print actually looked painted on..
thought to my self 50 years this has been sealed up ..cool

Regards Ned
55 cab
56 coupe

[Alex Goodhart]

I was

[Craig Richter]

Alex, that's a bummer. When I first hooked-up Speedy's horns to 12v, about 14 years ago, it made no difference whether parallel or in series, loud either way. So loud you don't need more than a beep or two, and they've never missed a beep. B-in-law's '60 S90 ditto.

[WilliamVaughan]

Your very clear photo of a very nicely rebuilt horn does not show a drum shaped capacitor. Maybe it is there and I don't see it. But that likely explains why your horn will not work when series connected.
I recall that others have claimed to hook horns in series without problem.
I don't know what the value of the capacitor is in the other horns but I expect that it is only intended to reduce contact arcing, not facilitate connecting horns in series. Probably a ~0.1 mfd at several hundred volts.

[Alex Goodhart]

I have

[Wil Mittelbach]

As an alternative:
Suggest reducing the horns' 12v input to about 6v via a resistor at each horn's connection, and tune horns at their intended 6v operation.

[Mervyn Hyde]

I have an issue with my RH horn. A Bosch HO37 B-02. I have cleaned the contact breaker points and checked all the electrical connections and the mechanical operation of the vibrator membrane and the electromagnetic system. All seem fine and it was making a sound but was not adjustable to any extent. However, across the capacitor I am getting an OL. I can test and establish minimal resistance to each terminal clamp on each side of the capacitor. I am not keen on dismantling and re-assembling the highly sprung contact breaker system (a pain) but a couple of questions. First, what should be the capacitance of the yellow/orange capacitor? Second do these fail on occasion? Third, could one leave this one in place and fit a solid state (ceramic) capacitor across the terminals as an alternative to dismantling the system again?

EDIT: I have re-fitted the capacitor and its terminals and now I am getting up to 39m/ohms across the terminals and voltage through the system. However, with the points closed (cleaned and all fitted with the correct sequence of insulators according to the available schematics), I am not getting a magnetic 'pull' across the system??

[Fred Winterburn]

At least Bosch was clever enough to add a capacitor. Not only will it make the contacts last much longer, the horn will be louder as the amplitude will be greater with the cap. I would suggest using a 10µF to 50µF. 10µ is easy to get in a film type, or go with an electrolytic if a larger capacitor works better. As far as putting two horns in series, I wouldn't. The idea mentioned of putting a resistor in series would work too, but it would have to be high wattage as a single horn probably draws 10-15 amps (as a complete guess without measuring). If driving two 6V horns from 12V, I would be tempted to try a 1.5ohm or 2ohm ignition ballast resistor in series with each horn. I am going to rebuild the original Lucas horn for my Morgan and I will be installing a capacitor which they never had. Fred

I have an issue with my RH horn. A Bosch HO37 B-02. I have cleaned the contact breaker points and checked all the electrical connections and the mechanical operation of the vibrator membrane and the electromagnetic system. All seem fine and it was making a sound but was not adjustable to any extent. However, across the capacitor I am getting an OL. I can test and establish minimal resistance to each terminal clamp on each side of the capacitor. I am not keen on dismantling and re-assembling the highly sprung contact breaker system (a pain) but a couple of questions. First, what should be the capacitance of the yellow/orange capacitor? Second do these fail on occasion? Third, could one leave this one in place and fit a solid state (ceramic) capacitor across the terminals as an alternative to dismantling the system again?

EDIT: I have re-fitted the capacitor and its terminals and now I am getting up to 39m/ohms across the terminals and voltage through the system. However, with the points closed (cleaned and all fitted with the correct sequence of insulators according to the available schematics), I am not getting a magnetic 'pull' across the system??

[Mervyn Hyde]

Thanks Fred. Good input as usual. I believe that the original wiring to each horn is independent. If I added a film type cap across the two terminals to the existing old cap, that would at least test the operation of the existing one?

[Fred Winterburn]

I would remove the old cap or at least one lead before trying a new one in its place. I have no idea what they used for a capacitor, but chances are it's no longer reliable and could be shorting with enough voltage applied and the voltage could easily rise to 50 or more volts across the contacts. Fred

Thanks Fred. Good input as usual. I believe that the original wiring to each horn is independent. If I added a film type cap across the two terminals to the existing old cap, that would at least test the operation of the existing one?