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Re: [TCML] Notes on first SRSG...
I'd like to amplify one of the points John made below that I failed to
mention in my reply. Even with a well-made Freau phase adjuster, it is
still necessary to make an initial trial and error ballpark mechanical
adjustment between the motor shaft and disk or motor and cradle. Any Freau
adjuster has a limited range and it needs to be somewhat close.
Please post some photos, as there are any number of other issues that can be
a factor that we just have no visibility into. Also, more info on your
motor and gap arrangement may be useful.
Regards, Gary Lau
MA, USA
On Sun, Jul 4, 2010 at 11:36 AM, <futuret@xxxxxxx> wrote:
> Joe,
>
> Are the rotary gaps set close enough together for reliable firing? If the
> electrode spacing
> is too wide, the rotary will only fire at a high variac setting. Of course
> if the electrodes
> are tungsten and are set too close they can crash and break off. In any
> case
> the coil should begin firing at a lower variac setting I would think. 25nf
> should be
> OK for a 15/60 NST. 25nf should not be too large to fire reliably.
>
> The phase setting for the SRSG can only be set by adjusting for longest
> sparks.
> It cannot be adjusted using a scope because the firing timing depends on
> the
> exact characteristics of the NST and the cap value. The phase setting
> should
> not be set without the resonator in place. That can damage the caps and
> won't
> work anyway. You may be able to get in the general ballpark range using
> a scope, but I didn't bother in my own work.
>
> The phase controller gives only partial phase range. If you get best
> results
> at the end of the phase controller variac range, then you'll need to rotate
> the motor itself some in it's mounting cradle, or shift the rotor relative
> to the
> motor shaft to get the proper range. Of course the phase setting will be
> very different for the 25nf cap and for the 18nf cap. This may be why you
> got better results with the 18nf cap (or part of the reason).
>
> If you watch the rotary spinning under fluorescent light, you'll be able to
> see if it's truly running in sync (just the rotary alone, no Tesla coil
> firing).
> The light pattern will rotate if you lower the rotary voltage so it drops
> out
> of sync, and you can hear the hunting sound when it's almost syncing
> as you raise the voltage. (I'm referring to the motor voltage not the
> phase shifter variac setting). You can just unplug the motor and you'll
> see the light pattern start rotating, then freeze when you plug the
> motor back in and it syncs. Some people have a very very very hard
> time seeing these patterns under fluorescent light however.
> (Maybe you did all these verifications tests already).
>
> The sound of the system should be 120 BPS, not 60 BPS. You should
> be getting 56" sparks or so if you're using a step up type variac
> (140volts).
>
> I'm surprised the variac has to be turned up so high for the static gaps
> to fire. Maybe the static gaps are set too wide? I'm assuming you
> have the coil tuned correctly at the primary tap. I didn't verify using
> JAVA TC or anything. You'll probably need to tune outward by a turn
> or two more than JAVA TC suggests, because JAVA TC doesn't
> account for spark loading effects on the tune point.
>
> John
>
>
>
>
>
>
>
>
>
>
> -----Original Message-----
> From: Joe Mastroianni <joe@xxxxxxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Sent: Sat, Jul 3, 2010 11:02 pm
> Subject: [TCML] Notes on first SRSG...
>
>
> HI All,
>
> I got my first SRSG running today. Some notes, and maybe you experienced
>
> fellows can enlighten me on the phenomena I'm observing --
>
>
>
> - Running a 15/60 NST. 17 turns of 1/4" x 1/4" refrigeration line as
> primary.
>
> 22" tall, 30GA, 4" dia secondary. 25nf MMC (3 banks of 18 0.15mf by
> 2kV).
>
> Tophat is an 18" x 4.5" spun toroid. Using 2 variacs - one in John Freau's
>
> phase-shift configuration, and one for primary power.
>
>
>
> - Experimented running with the static gap and 25nf, instead of 18nf on
> the
>
> MMC. With 25nf on the MMC the variac has to be an nearly 120V for the
> static
>
> gap to fire. It's kind of all or nothing. Turning on the primary is
> around
>
> the 13th turn in this configuration
>
>
>
> - Switched to the rotary gap - difficult to "tune" the SRSG phase in this
>
> configuration, because you either get it to fire, or not, with max power on
> the
>
> power variac. Lots of trial and error.
>
>
>
> - Tried tuning the phase without the coil resonator connected to the SRSG.
> Sort
>
> of works...think I got it firing right.
>
>
>
> - Took the 3rd bank of the MMC off - and lowered the total tank cap to
> 18nf.
>
> Now the gap fires at lower voltages, and I can tune the phase. Though now
> I'm
>
> worried I should switch back to the 25nf capacitance to avoid blowing
> something.
>
>
>
> With 18nf capacitance and the SRSG rotating in what I think is a reasonable
> sync
>
> phase with utility power - I'm getting some really great results. Sparks
> are
>
> bright and "mean" sounding - full of what I presume to be 60hz buzz.
>
>
>
> Is there any reliable way to tune the phase of the SRSG with a scope (or
>
> without) - without having to rig up some kind of optical strobe sensor?
>
>
>
> Thanks to all for the help!
>
>
>
> Joe_______________________________________________
>
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>
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>
>
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