Homebrew_PCBs

OK, I'll start asking specific (and ignorant) questions.

What are the important measurement parameter(s) of the spark? current,
I'd guess. others?

What is the optimal spark voltage range?

How do you measure? Standard shunt techniques? ...?

Is the spark long lived enough to measure directly?

What is the relationship of gap to spark current?

How do you tell between a short and a spark?

Is there a range of spark currents that allow one to adjust electrode
gap via PID or similar algorithm?

What effect on the spark does the electrode shape and/or material have.


By the way, a raster approach could be sped up by using multiple spark
electrodes. Might have to offset them a bit though I'm not sure about
that. Any reason why one should not use a bidirectional raster
approach (LR, RL, LR ...)

Phil

On Sat, 09 Jul 2005 09:37:26 +0200, Phil <phil1960us@...> wrote:

> OK, I'll start asking specific (and ignorant) questions.
> What are the important measurement parameter(s) of the spark? current,
> I'd guess. others?
> What is the optimal spark voltage range?

See the theory on the page with the eden supply.

> How do you measure? Standard shunt techniques? ...?

current is limited via a standard shunt / opamp, yes.

> Is the spark long lived enough to measure directly?

certainly.

> What is the relationship of gap to spark current?

The current is limited, no relationship. (If the gap is too big there will
not be a spark and no current.)
As i understand it once there is a plasma path any amout of current could
flow, so it is strictly limited by the supply.

> How do you tell between a short and a spark?

voltage.

> Is there a range of spark currents that allow one to adjust electrode
> gap via PID or similar algorithm?

As i understand it gap is adjusted by (gap) voltage, too high -> go
closer, too low-> short.
I guess one must sample that during spark. the eden edm pages speak about
you basically minimize the occurence of too high/too low readings. The
eden supply has only digital outputs for "spark" and "short", it appears.
I believe a analog measurement of the gap voltage (maybe with sample and
hold, maybe with a MPU). I do not understand how exactly the eden PSU
works here, with the diodes on the output it measures something in some
way. Not sure.

> What effect on the spark does the electrode shape and/or material have.
> By the way, a raster approach could be sped up by using multiple spark
> electrodes. Might have to offset them a bit though I'm not sure about
> that.

time is not a issue right now, for me. first one must work!