Re: Dimmer Switch, continued

[Marc A Levy <malevy@xxxx>]

the 2K ohm scale is too high for a dimmer switch. Most of the DC
dimmers used in cars are at most 25 Ohms. As far as I can tell, the
part used in the DMC is about 4 Ohm Max. Based on your measurements, I
would guess that you have a 25 Ohm part. .030K Ohm is 30 Ohms.. The 5
Ohm error is to be expected on the scale you are using, especially if it
is a analog meter.

If the above guess is true, then your dimmer probably darkens the lights
more quickly than the stock dimmer, and may even have a larger portion
of the control range where the lights are off (or VERY dim), as compared
to the stock dimmer. Maybe we can hook up in Cleveland and compare.

The "Taper" is used to describe what the curve would look like if you
were to graph resistance VS rotation position. I would guess that all
of the dimmers are linear, although they dont have to be.

The shaft style you describe is common to Lucas parts, although I have
found that Lucas is the only company that uses this shaft style making
it impossible to use a non-lucas part and keep the look stock.

The information you supplied on the Jag is helpful. I am going to see
if I can find that part locally to check it out. It it is cheap enough,
I will take it apart and see how similar it is to the DMC part.


Dave Stragand wrote:
> Well, using my handy-dandy multimeter, I get the following, and bear in
> mind it's been about 12 years since high school physics: On the 2k ohms
> scale, I get a steady proportional range from .001 through .030. A
> little bit more and it jumps to 1 (open)
> 
> The taper is a hexagon approximately 3/4" tall by 1/4" thick, with a
> small round spring loaded pin centered a shade less than 1/4" from the
> top of the post.
> 
> I'm no electrician, but I do know it makes all the dash lights dim from
> off to full on with no problems so far. If it's from 1976, that means
> if it's a Jaguar part likely from 1977, so it's either from an XJS or an
> XJ6/12. Since the XJS appears to use something similar to a rocker
> switch, it may be from the XJ6. According to a Terry's Jaguar catalog,
> the XJS uses a different switch from the XJ6/12. Terry's lists this as
> as Jag part number 30886. Anybody have access to a Jag dealer locally
> that could check it out?
> 
> -Dave