Re: EDM home brew units ?

Dave,

the application of the supply during discharge will have very little
effect as the relative currents/resistances are so different.

you were talking about a round robbin approach, charge each capacitor
while not connected to the gap and then connect it to the gap for
discharge. You are talking about setting the gap voltage but you
can't do that like you do with a free running RC circuit because the
cap will always be charged (to some level) when applied to the gap.
You could change the level you charge it to but then you would need to
control the gap by looking at how long it took to discharge or
something. Shorter discharge suggests lower gap resistance and hence
closer to arcing. Long discharge times or no discharge suggests O/C.

>If one were to set a lower limit of, say, 35 volt, and open the
>electrode at that point, a shorter pulse would occur, but also the
>pulse would have signifigantly more energy per pulse.

Less energy E= 1/2CV^2

>the duty cycle would be faster as well.

duty cycles do not have a speed, they are a ratio.

>if one were to use two, parallel circuits, but with each being set to
>charge while the other is pulsing, then a rapid fire pulse train
>would be seen at the electrode.

I asked how you would control the gap not why you want to use multiple
caps. You have to move the electrode to control Rg and you need some
feedback signal to do this.

Graham