Motor questions, rotary

Quoting Steve Roys:

 SR> I just bought a 1/12 HP, 5000 RPM  variable speed DC motor   
 SR> and I have a couple of questions.  First, is this powerful   
 SR> enough to use to drive a rotary gap?  

I purchased a 1/12 (or 1/10 depending on which spec sheet I read)
Bodine series wound DC motor. It did not work well. The speed was
there, but the motor just could not produce the required torque.
The rotor speed would drift, when I added a flywheel it took too
long to come up to speed. 

I switched ober to a 1/2 HP 10000 RPM DC motor with much better
results. The motor basicly just idles at speed. The armature is
heavy enough it acts like a built in flywheel.

 SR> Secondly, can I get DC to drive this motor by simply running 
 SR> the output from my variac through a full-wave bridge, or
 SR> should I put in some filter caps to smooth out the ripples?

This depends on the component arraigments. If your run the rotor
directly off the motor shaft you can expect to lose a full-wave
bridge now and then. If you run the rotor on a separate shaft,
which is belt driven from a pulley on motor, then you won't have
a problem.

 SR> And a suggestion for Ed concerning your rotary gap: instead  
 SR> of adding more rotating electrodes to get higher break       
 SR> rates, it might be easier to add a second set of stationary  
 SR> electrodes positioned to fire halfway between the first set. 
 SR> This would effectively double your break rate and you        
 SR> wouldn't need to have a new disk machined.

Good point! I should have thought of this.

Richard Quick
... If all else fails... Throw another megavolt across it!
___ Blue Wave/QWK v2.12