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Re: Audible buzzer

To: DANMAS@aol.com, triumphs@Autox.Team.Net
Subject: Re: Audible buzzer
From: Trevor Jordan <trevor.jordan@rmit.edu.au>
Date: Wed, 8 Oct 1997 13:01:06 +1000
At 23:53 +1000 7/10/97, DANMAS@aol.com wrote:

>The turn signal indicator light in a TR6 is a very interesting circuit. One
>side of the bulb is connected to the right hand turn signal lights, and the
>other side is connected to the left hand turn signal lights. When, for
>example, the right hand turn signal is on, power is applied to the right side
>lamps and the indicator bulb, and the indicator bulb finds a path to ground
>through the left hand turn signal lamps. The opposite occurs when the left
>hand turn signals are on.
>
>As you can see, with this arrangement, the buzzer will only sound when you
>are using the side which the buzzer is connected to. When using the other
>side, there will be no voltage on the buzzer.
>
Well, who was responsible for that clever bit of design: Triumph or their
co-conspirators at Lucas?

A couple of possible solutions come to mind:

1. use two buzzers, one in each direction accross the indicator light
wiring - they are cheap, and although they are definitely polarity
dependent, they may not be damaged by the frequent application of reverse
potential (only time will tell - there was no warning on the packaging).
[Marketing point - if a buzzer fails, then only one direction of turn will
be affected.]

2. use a small bridge rectifier - also cheap, but it could be a bit messy
to make all those connections behind the dash and insulate them properly.

3. find a suitable polarity insensitive buzzer.

Since I have already purchased one buzzer, I will try that first to see if
it is compatible with the indicator lamp wiring.  If it is, I will try 1 or
2 above.  If not, I will pursue 3.  Expect a progress report after the
weekend.

Trevor Jordan
74 TR6 CF29281U (no overdrive - but an overdrive light would be impressive,
or maybe a turbocharger light or an afterburner light!!!)



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