Jim Parent wrote:
>
> Steve,
> Optical pickup? I don't see what you mean.
> Hall effect? I'll pass on that one too.
> Regards,
> Jim
> B9470139
Jim,
The Mallory "Unilite" type distributor is exactly that, "a single
light". A light source, sometimes an LED (light emitting dioide) is
placed just opposite a light detecting device (sometimes a solid state
transistor with a clear portion of the plastic body to allow light to
strike the light sensitive silicone). A plastic "shutter" is placed
between these two devices. In the "Unilite" case, this shutter is a
slotted cup that fits on the main distributor shaft. As the shaft turns,
the slots alternately allow the light to shine thru. This "activates"
the switching circuit and takes the place of the cam and points to
interrupt the DC voltage to the coil.
There is yet another type of sensor that opens and closes as a magnetic
field is alternately interrupted. This could be as simple as a coil of
wire opposte a rotating magnet. The Ford electronic ignition, started in
the '70's, has a multi-pole magnet on the distributor shaft, whose
magnetic "blades"face a pick-up coil.
The Pertronic device does away with the coil, as the magnetic sensor,
and replaces it with a "Hall effect" transistor. This transistor is
magnetic field sensitive, rather than light sensitive, and closes
circuit in the presence of an adequate magnetic field generated by the
"blade" of the new rotor.
All of these techniques have their good and bad features. The most
important being the quality of the components and their design. Unilite
has and excellent reputation, as does the Pertronic. Either can drive
the coil alone, or a "Capacitive Discharge" (CD) unit, which I won't
cover here.
Steve
--
Steve Laifman < One first kiss, >
B9472289 < one first love, and >
< one first win, is all >
< you get in this life. >
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