Re: SRSG's

["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 12/15/00 12:43:04 AM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:

> Hi John,
>  
>  Nice simple diagram at your web page - thanks!
>  
>  How did you come across the right value cap to use? (calc or experment?) 
If 
> you
>  calc'd, I'm simply wondering how you derived the correct value. Also, how
>  much phase
>  control do you get? I remember you indicated in a previous post, but I
>  can't recall.
>  
>  Thanks,
>  Bart
>  

Bart, all,

I just used trial and error, no calcs.  It still works with half or double
the capacitance, but with double, there's more resonance occuring,
and with half, the motor loses lock at the full phase shift.  If one is
willing to accept a smaller phase shift, the cap can be smaller.
For a 3600 rpm motor for which full phase adjustment range is
180 degrees, I get a 90 degree range of adjustment.  Using an 1800
rpm motor for which the full range is 90 degrees, I expect the circuit
will give a 45 degree range of adjustment, not sure though.

Of course the key may be the power of the motor.  A powerful motor
may tolerate a (relatively) smaller cap (resonance-wise) without 
un-locking (maybe).  It may also tolerate the installation of the
resistor to de-Q the circuit to stop the resonances that Terry
is concerned about.

John Freau