> DCC decoders use something in the region of 500Hz for most cored motors to
> have a frequency that is high enough to have a PWM signal that can produce
a
> good average voltage, without being that high that the losses in the core
> become a problem.
>
> However do be aware that more can type motors with coreless armatures are
> being used (Faulhaber, etc), and these require a frequency of the order of
> 20kHz. The reason for this is that the low frequency used for cored motors
> is low enough to mechanically vibrate the windings to a point where they
> physically shake apart. using 20kHz is above the mechanical resonant
> frequency of the armature winding, so the mechanical does not occur.

Maybe I was a little to unspecific - this model railway regulator is for
N-gauge (1:160). Coreless motors are the exception in this gauge. But the
idea is very helpfull - I should add to my project a switchable PWM
frequency for the added pulses.
As far I have understood the 12F683 there is only one internal PWM - should
this mean that I have to program a second one by myself?

Regards
Enrico

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