At 05:20 PM 3/23/2010, neil n wrote:
>Oops. Was looking at "Hall control unit" P 28.28 Bentley, but wrote
>the wrong thing.

I would call that a wrong label.  97.55 has correct terminology.

The Hall sender puts out a TDC pulse which goes to the idle stab unit
and is advanced or retarded if necessary to keep the idle speed
correct.  The output pulse goes to the ignition pulse generator and
tells it to initiate the switching output that pulls down the coil
negative to ground in a controlled fashion, thus generating spark in
the coil secondary.  It dissipates a fair amount of power, hence the heat sink.

Yours,
David