Re: Langlois's HSM EDM m/c question

>
> Like the orignal poster, I'd be very interested to hear if anyone

has

> built this 'advanced' model, what final circuit details they used,
> and what results were achieved.
>
> Dave M.
>

I just know this will result in some disagreements, but here goes. I
don't believe that those additional circuits ever worked. I have been
using the original circuit with one change which may be the reason I
could not get the PWM type stuff to do any thing outstanding. The
change I made was to use a light bulb to replace the power resistors
in the original circuit. Maybe the nonlinear characteristic of the
filament in the bulb does some funny things!

I also see some unexpected results when using different values of
capacitance. I find in my using the EDM that if a small capacitor is
programmed, the time to spark a hole is very nearly the same as if I
used a large capacitor. I assumed this was due to the fact that the
saw tooth developed, (relaxation oscillator), changed frequency due
to the different capacitance so that we knock off small chunks of
material with a higher spark rate in one case and large chunks at a
slower spark rate. What do you think? Richard