Re: high-performance EDM power supply

>What I found out during 6 months of collecting and reading articles
>is that the spark (desirable) and arc (undesirable) sensing
>circuitry can be quite sophisticated. Well, that was 30 years ago
>and there are integrated circuits and solid state devices now that
>are far better. Still, the sensing circuits are very important and
>these have to be connected in some sort of feedback mode to the
>stepper drivers.

That is certainly true but it MAY be a bit like using steppers. They
have no feedback but if you go slow enough you don't have trouble
with lost steps. I suspect (guess) that the same may also be true
for EDM in as much as for faster feed rates these controls become
more important. We are hobbiest so we might be able to relax it a
little.

>It used to be that the power supply would charge up a capacitor
>which would discharge causing a spark. This capacitor doesn't have
>to be large, but it will be expensive as it has to accomodate a very
>high cyclic discharge rate if you are going to have any speed at all.

That is for an RC type set up. If you are just wacking short voltage
pulses on the workpiece then the capacitor can be much bigger and
only used as the smoothing of the DC supply. This pulse type supply
seems to be used on all commercial EDMS.

Graham