Hysteresis vs synchro motors for TC work

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

Original poster: "D.C. Cox by way of Terry Fritz <twftesla-at-qwest-dot-net>" <resonance-at-jvlnet-dot-com>

 
Application note on hysteresis synchro type motors:
 
The best to use without any fuss is of course the true salient pole synchro
motors.  Problem is the higher cost.
 
The small hysteresis type synchro motors that we recently made available to the
Tesla list members work great at a reasonable price.
 
Some members assumed these motors would not work and would "random sync" all
over the 360 degree circle ---- not true at all.
 
When you activate the motor it always syncs in one of two places (1) right on
the 60 Hertz peak in which case the motor is snycing with the four "flats"
ground on the armature, or (2) at 45 degrees off the 60 Hertz peak in which
case the motor is syncing with the "90 degree corner of the armature".
 
It seems they sync approx 70% of the time right on the peak and the remaining
30% of the time at the 45 degree off-peak location.
 
We applied 4 flourescent dots (office supply store) near each electrode and use
Terry Fritz's small 12 VAC LED driver circuit to work as a cheap strobe.  We
used Digi-Key part number 67-1604-ND which is a high-brightness white LED.  Cap
is p/n P944ND and two resistors required, p/n's ALSR1J-10-ND and
ALSR1J-560-ND.  A 1N4001 and a small 12 VAC xmfr from the junkbox finished out
the project.
 
Mount the white high brightness LED on a small plastic "stalk" approx 2.5 in
away from your stationary electrodes.  It fires and you can see the flourescent
dots from nearly 6 feet away from the coil.  A few quick on/off flicks of the
additional "strobe switch" on your control panel and you are always in sync. 
Once sync is achieved it will stay there -- it does not "wander".  
 
You will find you will hit sync most of the time your turn on the RSG.  Only a
few times you will have to hit the on/off switch.  
 
We've used this same circuit on 2 HP hysteresis synchro motors with larger
coils, and it works perfectly.
 
Bottom line is you can use the hysteresis synch motors and they work fine if
you are willing to hit the on/off switch a few times.  A simple tradeoff to
save money on the more expensive salient pole type synchro motors.
 
Best regards,
 
Dr. Resonance