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RE: [TCML] Scope Issues

While the timing between successive bangs is extremely erratic when using a static gap, if one adjusts the sweep speed to show just one bang to the point of quench, the bang-to-bang repeatability is actually quite good and will show a reasonably stable display.  There will be some variability in bang amplitude from bang to bang, and this will result in differences in quenching, but one can usually overcome this by setting the trigger threshold high enough to just trigger on the highest bangs.  So the scope must be set to the trigger mode that shows no trace at all when the coil is off or when the trigger threshold is set too high.

If one is using a very old or cheap scope that does not have triggered sweep, then this probably won't work, but I've never tried using such a scope.  What kind of scope are you using?

Regards, Gary Lau

> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of Phil Tuck
> Sent: Thursday, May 07, 2009 9:39 AM
> To: 'Tesla Coil Mailing List'
> Subject: RE: [TCML] Scope Issues
> Greg.
> I can't answer your problem directly, but I have tried a similar thing and
> had some minor success, but if you like me have a static gap which at 1KW
> I'm guessing you may have, then you might be disappointed at what you get
> anyway, as the SG is a bit too eratic to get a decent sync on for the scope.
> If that turns out to be the case, try photographing the 'scopes display like
> I did, and you may be lucky enough to capoture a 'frozen' trace of what you
> want.
> Regards
> Phil
> www.follytowers.co.uk/tesla
> -----Original Message-----
> From: G Hunter [mailto:dogbrain_39560@xxxxxxxxx]
> Sent: 07 May 2009 01:58
> To: tesla@xxxxxxxxxx
> Subject: [TCML] Scope Issues
> I tried to observe my SGTC quench on my o'scope tonight.  No dice.  This is
> the first time I've tried it.  I set up a simple horizontal dipole about
> 15ft from the 1KW, NST-based coil.  I used two 18" wire elements across a
> 47ohm resistor.  I set up the scope for a good-looking 200kHz sine wave from
> my sig gen, then plugged in the dipole to CH1 and went for it.  The scope
> displayed zip, even at 5mV/div.  I tried vertical polarization too.  No
> help.  I removed the resistor.  The scope now became sensitive to 60Hz noise
> and showed me a fuzzy trace.  Good!  Still no help.  The snarling TC across
> the room inspired not even a quiver from the mocking trace.  I'm stumped.
> The vacuum cleaner motor on my sucker gap causes plenty of 60Hz hash on the
> scope, put the screaming coil causes no change in the display.  Were I a
> gambler, I would've bet the TC RF signal would be detectable from 10s of
> yards away.  What am I doing wrong?  Should I simply move the antenna
>  closer to the coil?  I don't have enough coax to do that at the moment, but
> I can get some.
> Cheers,
> Greg
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