Re: RSG adjustment

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

Original poster: "Steve White by way of Terry Fritz <twftesla-at-qwest-dot-net>" <slwhite-at-zeus.ia-dot-net>

I have a 1/2 HP motor in my RSG. I am currently building the John Freau
phase adjuster. I am planning on using 250 uF of capacitance. My proposed
solution to the self-braking problem is to use a double-pole switch to
completely remove the phase shifter circuitry from the motor and power
simultaneously when I hit the "off" switch. I have not tried it yet but I
don't see why it would not work.

By the way, what is the reason for the self-braking action? Is it the very
large impedance that the motor sees from the capacitors when it is turned
off and generating a back-EMF?

Steve: Coiling in Iowa

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Friday, March 22, 2002 7:00 AM
Subject: Re: RSG adjustment


> 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
>
>
>
>
>
>