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Re: Twin SSTC (fwd)

---------- Forwarded message ----------
Date: Sat, 07 Jul 2007 10:30:02 +0200
From: Finn Hammer <f-h@xxxx>
To: Tesla list <tesla@xxxxxxxxxx>, youngs@xxxxxxxxx
Subject: Re: Twin SSTC (fwd)

Steve, all,

With the secondaries tied to the same ground point, built and tuned to 
the same resonant frequency, and driven by equally identical primary 
circuits, I dont see how they would fail to produce nicely -mutually 
attracting, and connecting streamers.

This all depends on the ability to turn on the trigger SCR`s, without 
too big delay from 1 to the other .

I don`t have the measured data to answer that question.

The trigger arrangement of a twin T-SISG would work this way:

2 series connected IF-96 fiber optic LED`s are shining into each their 
1000um polymer fiber, to bring IF-95T fiber optic receivers into conduction.
The purpose of this stage of the trigger circuitry is to isolate the 
operator from the coil, and streamers hitting the ground ot the trigger 
The IF-95T is situated in the front end of a pulse generating circuit, 
which sends a current pulse trough the SCR trigger transformers in each 
SISG stage.
This step is necessary to isolate the pulse circuit, which is at ground 
level from the SISG boards, which are at elevated voltage levels.
The current pulse sent trough the trigger transformers produce the 
trigger voltage on the gate of the trigger SCR.

Look here for schematic:

The fiber optic receiver, a IF-D95T, has a propagation delay of 8uS, and 
the SCR`s, IR 16TTS12, have a turn on delay of 0.9uS.

Within these values, if they differ from part to part, it would be easy 
to build an adjustable delay circuit to correct for any differences on 
the component level.
So I`d dare to assume, that the Triggered SISG circuits could be made to 
conduct within a 500nS or so without going to too much trouble.

A 50kHz coil has a 180deg period time of 1/100000 = 10uS so 500nS is 
equivalent to a phase shift of 9 degrees.

Whether this is close enough to produce connecting streamers, I don`t 
know by experience, but considering that the voltage of a sine has 
reached 0.987% of peak level at 81 deg., my guess is that it is.
Actually, at 25 deg phase shift, the voltage is still within 90% of peak 

Greg, did you record how big a phase shift you had, when the streamers 
started to attract to each other?

Cheers, Finn Hammer

> From: S&JY <youngs@xxxxxxxxx


> Finally, I believe a twin TC driven with two SISGs, each triggered with the
> same pulse ala Finn Hammer style, wouldn't work well because there would be
> no way to phase lock the frequencies of the two coils.  Is that correct?
> Or, if the resonant frequencies of the two coils were almost identical,
> would they lock in phase via the streamer connecting the two toroids?

> All comments will be appreciated. 
> Thanks,
>-Steve Y.