Re: [TCML] rsg pulsing

[Quarkster <quarkster@xxxxxxx>]

Bart -
 
John's RSG is driven by a non-synchronous motor (DC motor with speed control, but no means to synchronize it to the AC line sinewave). Almost assuredly the "pulsing" symptom is caused by the motor running close to, but not at, synchronous speed. It would probably be relatively easy to convert this coil to a DC resonant-charged system, where the adjustable-speed DC motor will allow a very wide range of break-rates and different streamer effects. It would be relatively difficult to modify the motor speed control to maintain a speed of exactly 1800 RPM, plus somehow synchronize rotor angular position with the AC line sinewave. Conversion to a DC resonant-charged tank circuit would "only" require addition of a HV bridge rectifier, a HV charging inductor, and a HV de-Qing diode.
 
Regards,
Herr Zapp
 
 
 On Fri, 9/19/08, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:

From: bartb <bartb@xxxxxxxxxxxxxxxx>
Subject: Re: [TCML] rsg pulsing
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Date: Friday, September 19, 2008, 6:32 PM

Hi John,

As Zapp mentioned, the mechanical coupling appears concerning, but I've 
also seen these couplings used in rather large loads in gear style 
applications which couples a gearbox to a motor shaft. So, hopefully, 
you've thought about that and accounted for the disc load.

The pulsing can be mechanical or electrical. As mentioned, there is a 
great deal of cable length from box to box. It wouldn't surprise me if 
you were causing an electrical resonant frequency feeding back to the DC 
Controller mains, and thus pulsing the DC voltage. Any way you can 
measure the DC output with a scope while running? If so, you should be 
able to track down the cause. Seen on DC? if yes, is it on AC mains to 
the controller? If yes, then move input to an unaffected circuit. I 
doubt a DMM would sample fast enough unless the pulse is rather slow.

Take care,
Bart

Quarkster wrote:
> John -
>  
> I think the answer to your "pulsing" problem has been adequately
answered both here and on the HV list, but I have two additional questions for
you:
>  
> 1. Is the mechanical coupling between the DC motor and the RSG disk
fabricated only from plastic (i.e. not a white plastic sleeve over a solid metal
coupling)? If the entire coupling is plastic, I'd be very concerned about
the mechanical reliability of that much mass, overhung that far without an
outboard bearing, and secured only by a few set screws threaded into plastic. 
>  
> 2. It looks like you have literally yards of wiring in your primary
circuit, connecting RSG to tank cap, and the actual primary coil is even further
out of view. This adds a lot of inductance; did you add this inductance into
your primary resonant frequency calculations? Ideally, the tank cap, spark gap,
and primary coil are close-coupled to keep intercorrecting wiring as short as
possible, measured in inches and not in yards.
>  
> Regards,
> Herr Zapp
>   
>
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