Wow, to listen to all you electrical guru's just amazes me. I took the easy
route and put a volt meter in my 72 TR6 (equipped with an amp meter) and a
volt meter in my TR3A (same). Best of both worlds. :o)
Alex
----- Original Message -----
From: "Randall" <tr3driver@comcast.net>
To: "Triumph List" <triumphs@autox.team.net>
Sent: Tuesday, August 08, 2006 06:03 PM
Subject: RE: [TR] Using a fuel gage as the basis for a voltmeter for my TR4
> > One thought was that a transistor biased by the system voltage
> > could be used
> > to simulate the resistance of the fuel guage sender, this would also
need
> > to have an external voltage reference of some sort to keep the
> > voltage level from affecting the guage reading.
>
> Er, but I thought that was the point, to have the voltage level affect the
> gauge reading ?
> <VBG>
>
> Dave has gently pointed out that I was thinking only of the TR3 fuel gauge
> ... the early TR4 fuel gauge is a voltmeter (of sorts) and might make an
> easier conversion. Since it actually responds to power (which is the
square
> of voltage), the result will probably be pretty non-linear, but that's
> exactly the way the later voltmeters were, so at least it will be
authentic.
>
> > I could bias the transistor to use the
> > full swing of the guage. I'll bet there's many ways to do this.
>
> Sure there are. You could even hook up a Basic Stamp and have it measure
> the voltage, then look up a calibration curve and drive the meter.
>
> > The Ammeter may show zero or full
> > swing (depending on if your car is on fire or not)
>
> The neat thing about the ammeter (IMO) is that it shows full swing
_before_
> the car catches fire. The later voltmeters respond so slow that you can
> smell the smoke, be pulled over and out of the car before they manage to
> drop to zero. The ammeter gives me time to try turning everything off
> first.
>
> Mine also goes full charge whenever I start the engine with a low battery,
> letting me know that even though the battery voltage hasn't come up yet,
the
> battery is being charged. I guess you could say the key difference is
that
> the ammeter tells you what is happening right now, not what happened a few
> minutes ago.
>
> > I guess, at the end of the day, we all like these cars - that in
> > some way like doing things the hard way or we'd all be driving newer
cars
> > with computers and valves you don't have to adjust.
>
> Well put !
>
> > After finish sanding all
> > the spokes on all my wheels, this seems like a cakewalk.
>
> Yow ! I'm just barely enough of a masochist to clean and wax them once in
a
> blue moon. I'd much rather drive the car than work on it.
>
> Ciao
> Randall
>
> PS, I checked ... it's gauge, not guage. Even for the British.
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