Re: Advice for an Old Coiler

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 7/19/01 10:47:46 AM Eastern Daylight Time, 
tesla-at-pupman-dot-com writes:

> Original poster: "Dave Kyle by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
<dave-at-
> kyleusa-dot-com>

Dave,

Welcome back to the world of coiling.  I don't think the extra caps
will actually give longer sparks, but it may help to protect the NSTs,
although the 0.015uF value is slightly LTR, and will hold down the
voltage some.  0.03 would be an ideal LTR size though.

>  
>  What diameter disk is recommended for an 1800 RPM SRSG? I was thinking 6
>  inches but others seem to prefer wider disks. Why is that?

A larger disc gives a faster mechanical dwell time, and also gives
less likelihood of a flashover from electrode to center hub of the rotor.
I use a 5" disc on a 12/30 NST for 42" sparks, so it's very probable
that you can get away with a 6" disc.  The mechanical dwell time
won't matter much at 120 bps anyway.

>  
>  I was planning on four stationary gaps in series with four rotors. Is this
>  the best arrangement?

Yes, probably.  Often just two stationary gaps works about as well.

>  
>  How wide to adjust the gaps in a SRSG?

They should be quite narrow, at about 0.010" to 0.015" or so.  If
they're too wide, the coil will not run smoothly and will give shorter
sparks.

>  
>  My synchronous motor may need to be replaced as I am unsure if it is of the
>  type that syncs from the same position at startup. It is a brand new
>  synchronous motor from Oriental Motor. Has anyone any experience with 
these?

You can test teh motor by placing a cardboard disc onto the shaft as
a rotor, and draw a white or black line across the disc.  Then run the
motor under fluorescent lighting.  You will see the pattern "lock up"
at a certain variac voltage.  Start and stop the motor a few times to
see if it locks at the same position every time.  
>  
>  It also remains to be seen if a 1/30 HP motor is going to be adequate. My
>  disk will be fairly light weight so I think it will be ok.

Very possible that it will be OK.  I'm using a 1/20 HP motor for a 
6.5" rather heavy rotor.

>  
>  What options for electrically varying the sync position of a motor exist?

A variac alone can give a slight phase adjustment.  For a larger phase
shift, my sync gap phase controller circuit can be used:
 
  http://hometown.aol-dot-com/futuret/page3.html
>  
>  Since all the high voltage components will be located beneath the secondary
>  how do you shield the power wires between the control panel and the NSTs
>  from ground strikes?
>  
>  I should think the addition of a large toroid would yield larger sparks.
>  Where can one purchase a 24x12x6 spun aluminum toroid? How much should I
>  expect to spend?

Yes, a toroid of that size should be useful,  a good price would be about
$160 or so.  Jim DeLilo may have some more available from teh bulk buy.

You should have no trouble getting 3 foot sparks.  A coil like that
can actually give 62" sparks or so, assuming a 140 volt variac is
used to power the coil.

John Freau
---
>  
>  
>  All suggestions welcome, I prefer to stand on the shoulders of giants.
>  
>  Thank you!
>  
>  Dave
>