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Re: Dwell time, etc



Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Phil,

I still have a couple schematics of triggered gaps at classictesla.com, and I've built both listed below. I started with Ted's design and later adapted Jon's driver circuit for more consistent firing at frequency. The basic idea is to build a static gap with larger than normal gap width and connect one of the electrodes to the trigger driver. The trigger driver will insert a pulse with a much higher voltage at 120 bps (60 Hz) or 100 bps (50Hz) capable of arcing the gap. The trigger arc essentially reduces the gap width during the quick pulse which allows the energy in the cap to fire across the gap.

The trigger makes it a "timed" gap vs a voltage controlled gap. There could be further enhancements to these designs if one wanted to go down that road.

Jon Tebbs Zero-Crossing Sync Variable Delay Trigger Driver circuit.
http://www.classictesla.com/download/stsg_zc_driver.gif

Full write up by Ted Rosenburg's design complete with part numbers.
http://www.classictesla.com/download/tgap.pdf

Take care,
Bart



Tesla list wrote:

Original poster: FutureT@xxxxxxx
In a message dated 4/3/06 9:10:52 PM Eastern Daylight Time, tesla@xxxxxxxxxx writes:


In a message dated 4/3/06 2:27:49 AM Eastern Daylight Time,
tesla@xxxxxxxxxx writes:

>I did some tests and
>compared the spark length using a sync rotary, compared
>to a triggered sync static gap.  The triggered sync static cap
>had about a 5/8" spacing.

     John-

     Any more details or photos of your triggered static gap?

-Phil LaBudde



Phil,

I don't have any photos.  The design was based on teh work
of Mark Metlicka a number of years ago.  We used a lamp dimmer
(actually a motor controller) to vary the triggering phase.
A GM ignition coil was used for the high voltage to the trigger
electrode.  The gap itself was formed from two round discs
of metal 5/8" apart with the flat faces facing.  The 1/8" wide
pointed tungsten electrode aimed towards the center of the
gap.  I'll see if I have more details in my notes.  The gap
was extremely loud and bright.  Much much louder than a rotary.

Many others on this list had built similar gaps back then.  I assume
they're still on the list, not sure though.

John