fusible link questions

[Van Setten, Tim (AZ75)]

> KD6JDJ <KD6JDJ at aol.com> wrote:
> 
> >  [[ I am curious about how a professor has determined that automotive
> >alternator diodes will have a forward voltage drop of 2 volts.]]
> 
> The diodes in the alternator are passing 100A or more, so even a small
> increase in resistance with current can produce a significant drop.
> 
> 2V at 100A seems reasonable to me. The only way to tell is to measure it
> though.
> 
	Just a note:  Older alternators used silicon diodes.  The newer ones
use a higher efficiency type known as Schottky type.  They usually have a
forward drop of about .45 Volts.  The GM CS style alt's are of the Schottky
style.  I've also been told that all of the new GM CS alt's are also using
the avalanche style of diodes as well.
	Don't expect to get much power out of a alt. at 120 Volts at 60 HZ
because there is not enough core for the stator to support the flux density.
This is why they run at about 400 HZ.  If you look at the output with a
scope you will see that it is more of a pulsed DC than an AC waveform.  An
electric drill (with a universal motor using brushes) doesn't care what you
feed it.  It will work.  If you notice any of the portable generators for
120 Volts 60 HZ, the generator section is HUGE compared to the same wattage
for a car alternator at 12 Volts DC.  It's the operating frequency that
allows the car alt to be so small.
	Tim.