Re: MOT Coil operational notes

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Gregory Peters by way of Terry Fritz <twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>

Ted,


 > 1) ASRG (up to 3000bps) works but not as well as SRSG  (in
 > terms of spark

(I'm not sure exactly on the type of gap you are using, but I seem to
recall you saying it was 15000 RPM)

3000BPS is pretty high - how does it go at say, 600-800 BPS.

I think running over 1000BPS is really a waste of time.

I would try running at about 600-800BPS, making sure the dwell time
is low. Are you running a decent static gap in series with the RSG??

The problem you may have is this:

To achieve 3000 BPS at 15000 RPM you need 12 electrodes. Therefore,
to run at 600 BPS, you must run at 3000 RPM. I don't know the size of
your electrodes and rotor, but I seem to recall it was just a
tungsten welding rod. Let's assume 200mm long, 5mm diameter.

Soooo, D=200mm, Circumference= 628mm

For 600BPS with 12 electrodes, you need to run at 50 RPS, which means
the velocity of the edege of the rod is 31.4 m/s

Therefore, the absolute minimum dwell time is 0.005/31.4

which is 0.00016 seconds, or 159 uS.

This does not take into account the fact that the gap may fire just
before and until slightly after each presentation.

Richard Hull, and the Corums did alot of work with async gaps and
found that the gap should quench in some TENS OF MICROSECONDS. There
is your problem right there. Your dwell time at "reasonable" break
rates is too high, so you get poor performance. You also need a
decent static gap in series to keep the quench time low.
SRSG quench times are less critical due to the extra time needed for
charging, etc etc.


Cheers,

Greg.
Also, Have you tried using a slightly smaller tank cap?