On http://www.autosite.com/garage/encyclop/ency04b.htm I found:

The Hall principle states that if a constant current flows through
a thin conducting material, and that material is exposed to a
magnetic field, voltage will be generated, and the amount of
voltage will depend on the strength of the field.

In an ignition system, this phenomenon is put to work by the action
of a shutter wheel in the distributor that interrupts the field
created within the Hall generator by a permanent magnet (this is
mounted across an air gap from a magnetically conducting element
with a thin semiconductor layer). The wheel has as many shutters as
there are cylinders, and they can be compared to the flat spots on a
distributor cam. The ignition control unit is designed to supply
current to the coil's primary winding while the shutter wheel is
blocking the field. When the shutter moves out of the way and Hall
voltage is produced, the control unit cuts off primary circuit
current, the coil's field collapses, and induction produces high
voltage in the secondary winding.

Check for more!
Helmut
'80 Camper
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>From: us014471
To: Multiple recipients of list
Subject: i dont know!
Date: Friday, 20 Sep, 1996 2:41

so What is a hall generater???

Dave wr3i
86 westy (many many miles)