Re: [TCML] SRSG setup and adjusting

[Gary Lau <glau1024@xxxxxxxxx>]

Hi Jeremy,

You mentioned that you have 4 electrodes, 90 degrees apart.  Is your motor
3600 RMP?  If so, you should only have two electrodes, 180 degrees apart.
This assumes you're looking for 120 BPS.  Having 4 electrodes will give you
240 BPS with a 3600 RPM motor.  That will work, but I don't think that the
performance will be as good.

Setting the motor phase must be done with the tank capacitor installed, as
that changes the phasing radically.  Even changing the NST Variac will
change the phase.  If you want to experiment with setting the motor phase
without tuning considerations and sparks, replace the primary coil with a
halogen lamp dummy load (previously discussed).  You don't need the pri &
sec coils to adjust the phase, but you must have the cap present,
discharging into either the pri/sec coils, or a dummy load.

As far as safety gap firing - it's critical that the tank capacitor be
appropriately sized for the NST(s) used.  If the cap is too small, the cap
will charge to a dangerously high voltage and (hopefully) the safety gaps
will fire. For a 15kV/120mA supply, your cap should be at least .05uF.  But
running at 240BPS would eliminate the hazard if you just don't have that
large a cap available. Kudos to you for not just readjusting the safety gap
so it stops firing!

I'll check my phase control Variac resistance later tonight.  If you suspect
that the wiper contact is poor and the cause of excess resistance, you'll
definitely want to fix or repair that.

Regards, Gary Lau
MA, USA




On Thu, Jun 2, 2011 at 10:16 AM, <jeremyee@xxxxxxxx> wrote:

> Hello all,
>
> I finally have my propeller style synchronous rotary spark gap built and I
> am currently in the process of adjusting the phase for presentations at the
> peaks of the NST voltage waveform. I currently have it setup with 4
> electrodes 90 degrees apart. I have a safety gap across the RSG as well as a
> "Terry Filter" safety gap. Please check out my blog for some visuals:
> theteslaplace.blogspot.com
>
>
> Here is my first question: can adjustments be made with the RSG connected
> to the NST only or does the RSG need the tesla coil loading for valid
> tuning? I have the Freau phase controller and I can get the RSG to arc on
> all 4 electrodes as well as just 2 electrodes but I haven't been able to
> find a phase setting (yet) that I can turn the NST voltage up all of the way
> and not get the safety gaps to fire. I have just started trying to rotate
> the motor in its mount and haven't found the sweet spot yet (I have a
> Teletype motor). So is it valid to adjust the phase without the
> primary/secondary circuit?
>
> The second question I have is about the motor behavior through phase
> tuning. When I have the variac that is adjusting the phase set with 90% of
> the windings in use, the motor will actually stop running (a bad situation).
> This is a variac that I had to repair and at the full winding position there
> is about 15 ohms of resistance. Is the motor simply being undervolted at
> this point or can an extreme phase cause the motor to drop out? My first
> thought is that it is not getting enough voltage at the full variac setting
> (I'll monitor that).
>
> Sorry for the long email. Rotary spark gaps are a new thing for me. I
> really appreciate any help! Thanks!
>
> Jeremy
> Cincinnati, OH
> Sent from my BlackBerry device from Cincinnati Bell Wireless
> _______________________________________________
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>
>
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