Author Topic: Horn button polarity  (Read 370 times)

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Offline Bucky

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Horn button polarity
« on: August 28, 2017, 09:30:44 pm »
For convenience, wiring diagram
http://forum.cog-online.org/index.php?action=dlattach;topic=59969.0;attach=32367;image
Thank you charger_john

Doing a Stebel wiring job. Is the current passing through the stock horn button negative or positive?
I'm guessing negative, but the neg side changes color here and there. I don't do a lot of wiring diagram work.

Thank you.


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Offline Harry Martin

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Re: Horn button polarity
« Reply #1 on: August 28, 2017, 10:05:59 pm »
For convenience, wiring diagram
http://forum.cog-online.org/index.php?action=dlattach;topic=59969.0;attach=32367;image
Thank you charger_john

Doing a Stebel wiring job. Is the current passing through the stock horn button negative or positive?
I'm guessing negative, but the neg side changes color here and there. I don't do a lot of wiring diagram work.

Thank you.


Bucky,

The switch itself has no polarity. But, what it does is provide a path to ground. One side of the horns is hot, +12Vdc. Current flows from +12vdc, thru horns, then horn button where it waits for the horn button to be pushed. When pushed, current then travels through button to ground.

On my C10, the horn button eventually stopped working as too much current fried the button switch. I eventually rewired it so that the button actuated a relay to power on the horns. No more fried horn button.
Harry in Wild and Windy Casper, WY - 1986 Vintage "Silverdammit" - 2015 "Greendammit"

Offline Bucky

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Re: Horn button polarity
« Reply #2 on: August 28, 2017, 11:09:39 pm »
So I'm thinking with a negative ground vehicle, the current passing through the horn button would indeed be negative.

Stebel has two wiring diagrams for single horn installs - one for positive through the horn button, and another for negative through the horn button.

My current Stebel relay contacts and socket somehow got corroded, and I have another relay and harness on hand, so I'm going to do it over.

I brought home from work everything I need to wire the new unit
except...

MY VOM !!!  :-[ :-[ :-[

Thanks for the post


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Offline JimBob

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Re: Horn button polarity
« Reply #3 on: August 29, 2017, 02:18:27 am »
I'm agonna be a pedant for a second (and see how much argument I can generate)...IIRC *electrons* flow from the negative to the positive side of a battery, and *electron "holes"* travel the reverse direction.


Can one of our resident EE's chime in and correct me where I've got it wrong?


But that tidbit aside, the horn switch is a grounding switch - as Harry said, power is always supplied to one side of the horns, and you complete the circuit through the horns to ground when you close the switch.


Pretty typical setup for horns as it's a simple design.


So the stebel's diagram should have a constant hot to the relay, and the other side of the relay (switching wire) will go to the horn switch. Can't remember the numbers on the relay, but one set of numbers drives the electromagnet portion, and the other set are part of the switched circuit.


Fortunately, reversing the wires on the elecromagnet won't make any difference, SO LONG AS...they aren't jumping from that hot to the other connectors on the relay.

Offline Nosmo

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Re: Horn button polarity
« Reply #4 on: August 29, 2017, 03:16:48 am »
Normally, for some reason, horns on cars and our Connies are wired "hot", meaning they have 12 volts applied to them and the switch makes and breaks the ground circuit, unlike other circuits where the ground path is wired straight  and the switch makes and breaks the power side.
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Offline Uncle Rob

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Re: Horn button polarity
« Reply #5 on: September 01, 2017, 01:37:30 pm »
I am not really sure on this, but normally switches are installed on the positive side of the load.  IE battery to switch, to horn, to ground.  If I am wrong, both terminals on the horn would show 12V whenever it is silent.
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Offline Nosmo

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Re: Horn button polarity
« Reply #6 on: September 01, 2017, 03:31:27 pm »
I am not really sure on this, but normally switches are installed on the positive side of the load.  IE battery to switch, to horn, to ground.  If I am wrong, both terminals on the horn would show 12V whenever it is silent.

Normally, that is correct.  For some reason, horns are different.
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Offline Harry Martin

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Re: Horn button polarity
« Reply #7 on: September 01, 2017, 03:57:48 pm »
Maybe this will help...

I grabbed a copy of the OP schematic from the link...
Made a few dozen or so edits to remove the extra wireing....to shrink it down a tad...
This is the results

If you carefully trace out the circuit, you will see that the horns are part of a circuit loop.
The horns are closest to the battery positive (after clearing the J-Box).
If you were to attach a VOM to any side of the horns (ignition ON), and reference to ground, you would measure +12 volts.
The horn side of the push button switch would read +12 Volts.

Push the horn button, and now you provide a path to ground providing power to drive the horns.
With button pushed (IGNITION ON), VOM would read zero volts on either side of the switch, and obnoxious horn noise if horns are working properly.
Harry in Wild and Windy Casper, WY - 1986 Vintage "Silverdammit" - 2015 "Greendammit"

Offline JimBob

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Re: Horn button polarity
« Reply #8 on: September 01, 2017, 08:48:24 pm »
I am not really sure on this, but normally switches are installed on the positive side of the load.  IE battery to switch, to horn, to ground.  If I am wrong, both terminals on the horn would show 12V whenever it is silent.

Normally, that is correct.  For some reason, horns are different.


Horns are different (I think) because it's a simpler wiring setup, especially when you have a horn button in the steering wheel. This eliminates concern over a wire carrying constant current from wearing and shorting in the wheel. It also means you need only one wire in the column, going through a rotating contact pad - otherwise that pad would require 2 copper bands, and be more complex.


On a bike this translates to a single wire going to the horn button, no "return" wire required.

Offline Harry Martin

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Re: Horn button polarity
« Reply #9 on: September 01, 2017, 09:39:13 pm »
Wiki has an explanation.  https://en.wikipedia.org/wiki/Vehicle_horn

Here is the typical diagram:



The horn is an electromagnet oscillating OFF and ON.
Harry in Wild and Windy Casper, WY - 1986 Vintage "Silverdammit" - 2015 "Greendammit"

Offline Nosmo

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Re: Horn button polarity
« Reply #10 on: September 01, 2017, 10:26:18 pm »
Well, sure here's the answer right in the Wiki article:

 Some motor scooters have this feature as well, placed below the handlebars. Their horn grilles may be made of cheap plastic.  :D
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