Horn - should it have continuity?

[LL - NY]

Addendum.  Since inductive loads create their "reactance" during current
changes, they tend to show as low resistance loads when tested as a DC
continuity test. This is one reason why coils are rather difficult to test
with a simple VOM.  A whole lot easier to test with an O-scope, you know,
the one that *everyone *has on their workbench (need some form of sarcasm
smiley). That being said, if you have an "open" test of a horn or coil, then
you absolutely KNOW it's bad.

LL - NY

On Mon, Feb 8, 2010 at 4:58 PM, <speedracer.mark at gmail.com> wrote:

> Absolutely outstanding!  I now have a perfect picture of what's going on
> inside the horn.  Brett was right and I was wrong in calling it a resistive
> load.  Lots of intelligence on this list, for sure!
> Mark Rosenkrantz
> Sent from my CrackBerry
>
>  -----Original Message-----
> From: LL - NY <larrycleung at gmail.com>
> Date: Mon, 8 Feb 2010 16:39:38
> To: urq<urq at pacbell.net>
> Cc: <quattro at audifans.com>
> Subject: Re: Horn - should it have continuity?
>
> Well covered Steve. It's an inductor. And the frequency is in lock step
> with
> the frequency of the horn note. Even an air horn is an inductor if it's
> motor compressor driven (such as the Griot's "Italian" horns), although the
> ones driven by mechanical compressor (Mack, Kenworth, White, M-B,
> ElectroDynamics (locomotive)) are not.  Until Piezo-Electric horns are used
> (never gonna happen, unless the hybrid people find horn energy consumption
> is a major issue) auto horns will always be inductive loads.
>
> On Mon, Feb 8, 2010 at 1:51 PM, urq <urq at pacbell.net> wrote:
>
> > Most automotive horns are buzzers, with the armature of the buzzer
> > connected
> > to a diaphragm to amplify the sound.  A buzzer is similar to a relay with
> a
> > N.C. contact in series with the coil winding.  When you apply power to
> the
> > buzzer it pulls the armature of the relay, eventually breaking the
> circuit,
> > which de-energizes the relay.  With the relay de-energized the armature
> > returns to rest the switch closes again, which re-energizes the coil.
>  This
> > mechanism is referred to as a relaxation oscillator.
> >
> > As Brett noted, a horn is a highly inductive load ... a fact accentuated
> by
> > the constant opening and closing of the contacts in the horn.
> >
> > Steve Buchholz
> >
> >
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