Add a high-power resistor into the horn circuit?
On Wed, Jan 27, 2021 at 5:34 PM Dave Connitt <dconnitt@fuse.net> wrote:
>
> Hi Jerry,
> The horn button controls a specific â??hornâ?? relay in this harness but
> itâ??s recommended current limit is 15 amps. The horns I have pull 17.25
> amps. The horns I have are new and I bet the original ones needed less
> current. I am going to call Scott Harper tomorrow and see if he has some old
> ones.
> I thought about increasing the wire size of the horn circuit.
> Dave Connitt
>
> Sent from my iPhone
>
> > On Jan 27, 2021, at 5:12 PM, Jerry Van Vlack <jerryvv@roadrunner.com> wrote:
> >
> > Dave are you going thru a relay? If yes then which fuse is blowing? You
> > could always increase the wire sizing from the relay to the horn and fuse
> > it accordingly. But why am I even giving advice to an EE?
> > JVV
> >
> > -----Original Message----- From: Dave Connitt
> > Sent: Wednesday, January 27, 2021 4:46 PM
> > To: Paul Tegler
> > Cc: triumphs@autox.team.net
> > Subject: Re: [TR] TR4A Horn Question
> >
> > I read through my Advanced AutoWire manual just now and it specifies a horn
> > circuit max. current of 15 amps so I will need to find some horns that have
> > a coil resistance of about 1 ohm if I donâ??t change anything else. I know
> > the relay is rated at 30 amps.
> > Sigh..
> > Dave Connitt
> >
> > Sent from my iPhone
> >
> >> On Jan 27, 2021, at 4:35 PM, Paul Tegler <ptegler@verizon.net> wrote:
> >>
> >> ...not sure of the coil spec...but just for a reference....
> >> a normal buss style fuse marked 'rating' is the spec holding current.
> >> (should not blow) It can take 10+ minutes to blow at 25% over the spec
> >> The 'voltage' rating is the guaranteed 'disconnect blocking' voltage after
> >> the fuse blows.
> >>
> >> So your horns must be spiking higher than the fuse rating to blow it
> >> quickly
> >>
> >> ptegler
> >>
> >>
> >>>> On 1/27/2021 3:50 PM, Dave Connitt wrote:
> >>> Hi All,
> >>> One of my winter projects is to determine why the horn fuse in my TR4A
> >>> keeps blowing.
> >>> I had installed a Advanced AutoWire harness during the restoration. The
> >>> harness contains a 20 amp fuse for the horn. The horns are new as of the
> >>> restoration. I went through the wiring harness and could not find a issue
> >>> there so now I am looking at the horns themselves and that is where I
> >>> need your help. I measured the horn coil resistance and it is 0.8 ohms in
> >>> both of them. If I use 13.8 VDC as my battery voltage, I get 17.25 amps
> >>> at the fuse which is too close to the 20 amp fuse rating in my opinion.
> >>> If the resistance was even 0.9 ohms, the fuse current would be a little
> >>> over 15 amps which would make more sense. Does anyone know what I should
> >>> see as a horn coil resistance on a good horn?
> >>> Thanks in advance,
> >>> Dave Connitt
> >>>
> >>> Sent from my iPhone
> >>> ** triumphs@autox.team.net **
> >>>
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> >>
> >> --
> >> Paul Tegler
> >> ptegler@verizon.net www.teglerizer.com
> >>
> >> ** triumphs@autox.team.net **
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> >
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