DeTomaso Mailing List: August 2000, Message #76

All:
Just wanted to let you know of the following on the headlamp pop up
unit. Decided to go for the motor changeout despite the reservations of
a few. The inertial concern that Rick Moseley had commented about will
definitely be studied. So far, a shorting mechanism might be in order.
I'll explain later. The other is the Ducellier motor itself. I know it
is reliable (like the Cleveland) but this motor could definitely be
updated. The motor I have chosen is of similar profile but smaller in
current draw. I do believe it is smoother and more powerful (it is a
German built unit).

To adapt the new motor to it's new surroundings, I built an adaptor
plate based on a 2.5" washer I got at the hardware store today. I also
picked up some stainless hardware. Later on, I stopped in San Luis
Obispo to pick up a pair of microswitches from the GC line. They are
rated at 15A per at 125VAC. Shouldn't be a problem for a 2 amp current
draw. Next thing to worry about was the footprint of the new
microswitches. Luckily, they just fit.

Now back to the inertial thing Rick was talking about. These motors are
DC magnetic units, right? Well, when power is applied, they operate by
the dc magnetic field induced in their coils that oppose the magnets
within, thereby turning. Of course, there is a commutator that switches
positions of the polarity of the motor such that there is a continuum of
motion within the unit. When the voltage is cut off, the motor continues
to spin (due to inertia). Shorting out the leads will cause a countering
magnetic field generate, thus slowing down the motor. I'll have to
investigate that but the "shorting out" leads are already present. The
microswitches I bought are the SPDT type so the other "unused" lead can
be used to short out the motor.

Back to the wiring. I decided I'll probably rebuilt the front section of
the harness...heck, might as well rebuild the whole thing and test each
circuit as the process goes along. I don't trust the old harness and the
new Painless wiring seems a bit too expensive (nearly $4-500 a pop).
Since I used to build and restore old radios (and rebuild their
harnesses), the P-car harness should be a piece of cake! Nuff said. Now
I'll hear the criticisms ;^).

O.k. I'll finish up the module with an assembly tomorrow. I POR'd the
plate (hey, do you guys know me by now???), and I'll follow up with a
paint with SEM trim paint. Cal.