Re: John's sync-adjust circuit

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

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

In a message dated 1/31/01 6:15:38 PM Eastern Standard Time, tesla-at-pupman-dot-com 
writes:

> So I figure on soldering the last cap back in and
>  using 5 (4.65uF). I was using Terry's modified strobe light to watch
>  the sync change during all this.
>  
>  I was hoping for the 90degrees that some have reported, but for some
>  reason I never could get more than about 30degrees. I still have the
>  handle on the motor for rough adjustments when changing transformers
>  and tank capacitors. The sync setting is very different when using
>  3000VA with .09uF and using 360VA with .007uF. 
>  
>  Alan

Alan,

Thanks for the report.  For an 1800 rpm motor, the mechanical
phase shift will be 45% at the most.  But this is equal to 90
degrees of electrical phase shift.  For a 3600 rpm motor both
the mechanical and electrical phase shift will be 90 degrees
maximum.

I am very surprised that such a small amount of capacitance
did the job.  For a 1/8th HP motor, I would have expected that
about 60uF would have been needed.  Does the motor remain
locked for the full range of the series variac?  Or do you have
to keep the variac within a certain range?  Is this about a 7.5A
variac or so?

John