Re: RSG adjustment

["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 3/22/02 12:22:25 AM Eastern Standard Time, tesla-at-pupman-dot-com
writes:


>
> !
>
>     I tried out the phase adj. circuit on John Freau's site, but apparently
> did not have the correct capacitor size.  I only have 2 large (10 uF or
> above) caps, and neither the 10 uF unit or the 35 uF unit worked.  Is
> there a formula I can use to find (or approximate) the needed size?  My
> motor is a 3/4 HP modified salient pole job, if that helps.  Also, is a
> 0-140 volt variac necessary?  Mine is not a step-up unit.



Winston,

A non-step up type variac is fine for the phase shifter.  Since a 3/4HP
motor is rather large, a large phase shift cap is needed.  You probably
need about 200uF or so.  You should see some resonant rise across
the motor at some variac position if you have the correct cap size.
The resonant rise should be about 2 to 6 volts.  You can always use
a bunch of smaller caps in parallel to obtain the 200uF or so.  If you
can't find the caps, then you'll have to phase the gap by trial and
error, by rotating the motor housing in its cradle, or by shifting
the relative position of the rotor to the hub.  Some folks have
built mechanical phase shifters that use a small motor to rotate
the motor in its housing remotely.  Some have use a long 
insulated pole to rotate the motor with a lever.  Some have use
ropes, etc.  Some have made the fixed electrodes moveable,
and used a remote small motor to move them, etc.  

If you do get the phase shifter working, beware of self-braking
in such a large motor.  This can cause the rotor to loosen if
it's not tight enough.

Cheers,
John


>
>     If I can't get the circuit to work, how should I go about accurately
> phasing my gap?  I can only approximate by moving the motor's housing
> (or is this the only thing to to?).
>
> Thanks,
> Winston