@ronv OK, what I think your saying is instead of a normal pull up you would use a diode replace the pull up. That sounds like it would work! But would a resistor still be needed with the diode? Or being a logic level from the timer out put the resistor is not needed?

Like the drawing below.

While the 'wait for an arc' seems like a bad thing, it really isn't. If the arc 'should' happen but doesn't it would usually mean the gap conditions have a problem. By waiting it gives the dielectric time to flush/clean the gap, which is the most common reason for no arc.

I think you have that backwards. Stuff in the gap (metal) makes it more prone to shorts not missing an arc. It is harder to start an arc than to keep it going. That's the whole purpose of the high voltage boost to try and get it to start more reliably.

 

Another question while talking about diodes. Will the 1N5817 diodes you showed in post#16 (I think) work for all of the small diodes? If so I'll get a bunch of them.

I think 3 types.
1N914 for the ones in the logic except where they are schottky, then SB190 and finally for the high voltage stuff 1N4007.

 

Like the drawing below.


I think you have that backwards. Stuff in the gap (metal) makes it more prone to shorts not missing an arc. It is harder to start an arc than to keep it going. That's the whole purpose of the high voltage boost to try and get it to start more reliably.

Drawing? Forget again?

The stuff that is in the gap will not be real metal anymore. It is a very hard 'carbide' type of material that is only semi conductive, and 'floating' electrically. Plus gases and carbon from the breakdown of the oil. There's a saying in edm, "the three most important things in edm are, flush, flush, and most importantly, flush." Many of the commercial machines have a circuit to retract the electrode every so many seconds during a cut, just to clear the gap.

Thanks for the diode numbers. I was going by that other drawing that showed 1n5817.

 

To many computers.

@shortbus

The on time setting determines the length or duration of the spark. Hence, a longer on time produces a deeper cavity for that spark and all subsequent sparks for that cycle, creating a rougher finish on the workpiece. The reverse is true for a shorter on time. Off time is the period of time that one spark is replaced by another. A longer off time, for example, allows the flushing of dielectric fluid through a nozzle to clean out the eroded debris, thereby avoiding a short circuit.

Once the current stops (or is stopped, depending on the type of generator), new liquid dielectric is usually conveyed into the inter-electrode volume, enabling the solid particles (debris) to be carried away and the insulating properties of the dielectric to be restored
https://en.wikipedia.org/wiki/Electrical_discharge_machining

 

To many computers.



The on time setting determines the length or duration of the spark. Hence, a longer on time produces a deeper cavity for that spark and all subsequent sparks for that cycle, creating a rougher finish on the workpiece. The reverse is true for a shorter on time. Off time is the period of time that one spark is replaced by another. A longer off time, for example, allows the flushing of dielectric fluid through a nozzle to clean out the eroded debris, thereby avoiding a short circuit.

Once the current stops (or is stopped, depending on the type of generator), new liquid dielectric is usually conveyed into the inter-electrode volume, enabling the solid particles (debris) to be carried away and the insulating properties of the dielectric to be restored
https://en.wikipedia.org/wiki/Electrical_discharge_machining

Only have one, and it's too many sometimes.

So using the diodes and the timer to ground pulls down the voltage enough that a 'high' signal is not capable? Is this how it works? Just trying to understand.

In experience, I don't agree with all of the Wiki. The current plays more in the roughness, size of the crater, than on time. When still working and starting to research this, many of the thing's the "experts" writing books said didn't hold up in real time. Even today they have as many theories as to what's happening in the gap as there are experts. Like most things having to do with 'plasma' involved processes. Just lucky that most things work as well as they do.

 

@ronv, I updated the schematic again, using the changes/fixes so far. Still didn't put in resistor values though, want to finalize design before doing that.

 

@ronv, I updated the schematic again, using the changes/fixes so far. Still didn't put in resistor values though, want to finalize design before doing that.

The diodes for the reset should be on the input to the inverters - back at the switch.
The arc current should flow thru the 2 big diodes and the top of the reference voltage should go to +12.
I've thought quite a bit over the last few days about the project and I think we have a few areas where we just won't agree.
1- how the window works with the motor.
2- derating the supply.
3- what to do if an arc fails to establish.

I think you should get someone else's input on these items. Maybe a new thread dedicated to each one. I will try to help you explain them to someone else, but I wouldn't feel right implementing something I don't think will work.

Good luck!

 

@ronv, all I can do is thank you for all your time and sticking with this as long as you have. You have gotten me to a far, far better point then I was in this.

1. the window/motor part of the circuit is the most established part of the whole project. All of the established plans sold and built use this. I just copied them.

2. don't even remember derating the supply being discussed.

3. don't know how to answer this.

Again thank you Ron, for all your help. Will attempt to build it from what you/we have given and report back when done. My 'summer' duties are starting to pile up and was going to have to take a break from this anyway. I'll start again when weather changes.