RE: Poor mans SRSG? Adjusting SRSG without Variac?

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

Original poster: "David Dean by way of Terry Fritz <twftesla-at-uswest-dot-net>" <deano-at-corridor-dot-net>

Hi Bill,

> 
> Without access to a machine shop, is it feasible to do the motor
> modification to convert an AC motor (1725 rpm) to salient pole
> synchronous (1800 rpm)?  What's the minimal set of tools required to do
> the job?
>
 
> Also, if I did manage to do the modification, is there some way to get
> by without a variac, as far as adjusting the spark gap is concerned?
>

The adjusting firing angle with a variac is a relatively new thing. Newer 
still, using a variac and capacitor to vary the phase angle in order to 
get even more adjustment of the firing angle with just the turn of a knob.
The classic way is just to adjust the timing until the best firing point is
found. If the motor you are going to use is mounted in a cradle, it is not
too hard. The first SRSG I built had slots in the rotor disk and the 
position of the disk was adjusted by loosening the screws and moving the
disk one way or the other. Some folks have come up with methods of rotating
the motor while it is running by remote control by mechanical means, or by
using a gear arrangement and a small adjusting motor. 

Adjusting the firing angle electrically by changing the
voltage and/or phase of the power to the SRSG motor is likely
to catch on quickly because it is so easy to implement and because
it is much less time consuming to adjust while running by turning 
a knob than it is to do it manually with the power off by trial and error.

Short answer: you don't need the variac for the spark gap. It is just a 
"nicety", not a necessity.

later
deano

   
> 	Thanks, 
> 	Bill Vanyo  (planning first coil)
> 
> 
>