[Spam] Re: [Ducati] Misc ponderings about regulators

[Barry.Haggerty at dtz.com]

Many years ago I converted my pre-unit 650 Triumph from 6 volt to 12 volt
electrics (mainly for quality of headlight output).  Part of the new wiring
system was a Zener Diode mounted on a heat sink which dumped the excess
alternator output in the form of heat.  Together with a rather large
capacitor to feed the distributor/coil ignition system (to eliminate the
need for a battery) the bike ran well for many thousands of miles, always
starting first kick.

I know that the alternator output on my Ducati (2001 900 SS) is many times
that of the old Tbird but am I being naive when I ask why not use a similar
system in today's machines?

Barry



Wrote

Very simplified version:

A shunt regulator monitors the maximum voltage in the charging system and
when it exceeds a set value, "dumps" the extra current into a bank of
resistors.  Your bike has one set of stationary windings that are excited
by
a rotating magnet on the flywheel.  This means that the windings receive
maximum excitation and are working at max all the time.  Any energy
produced
that is not required by lighting, battery charging etc is disposed of as
heat.

The alternator on your car has two sets of windings, a stationary set in
the
alternator body and a rotating set on the shaft.  The rotating set receives
a variable DC voltage at low current from the regulator, exciting the
stationary windings top produce the AC charging curent.  The output can
therefore be adjusted precisely according to the system's requirements at
any time.