Re: [TCML] rsg pulsing

[Quarkster <quarkster@xxxxxxx>]

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

--- On Fri, 9/19/08, John Forcina <forcijo10@xxxxxxxxx> wrote:

From: John Forcina <forcijo10@xxxxxxxxx>
Subject: Re: [TCML] rsg pulsing
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Date: Friday, September 19, 2008, 7:22 AM

Ok sure.  Here are some specs.  power suply 4 mot's around 8.4kv at 4.8kw.
primary cap 88nf 24kvdc cde 942c16p33k caps.  THe nameplate speed on the
motor is 1800 rpm so i may not be running it at exactly 1800 rpm.  Here is a
pic of how the rsg is set up.
http://flickr.com/photos/25967047@N07/2778479246/sizes/l/  Here is a pic of
my whole setup.  The orange thing attached to the left side of the variac
box is the dc motor controller.
http://flickr.com/photos/25967047@N07/2777622579/sizes/l/  I hope this
helps.

On Thu, Sep 18, 2008 at 10:02 PM, bartb <bartb@xxxxxxxxxxxxxxxx> wrote:

> Hi John,
>
> I just got back on emails tonight after a day or two outage, so I'm
> probably late on my reply (ignore if you've found the problem).
>
> I find pulsing odd in your case. This is likely a simple asynchronous
> rotary? I realize you specified 1800 rpm, but I assume that is just a
rated
> rpm for the DC motor? Can you give cap size, power source (MOT's?),
and gap
> electrode arrangement and spacing? Also, is it a constant pulse or
> intermittent? I'm probably not much help with this as I've never
encountered
> a problem like this with a rotary, but I wonder if the MOT's are
affecting
> the motor on the mains circuit. You mentioned 30% on the variac and both
> coil and rotary pulse. So I'm wondering if it pulsed at less voltage.
I
> expect it pulsed right when the coil began operating (but wanted to be
> sure).
>
> Take care,
> Bart
>
> John Forcina wrote:
>
>> Ok tonight i took my big coil out for a run since i havent really got
a
>> chance to tune it yet.  I noticed that as soon as i got it to 30% or
>> higher
>> on the variac the spark gap and coil started pulsing really bad. it
would
>> shoot 6' streamers for about 1/2 second and then stop for about
1/2
>> second.
>> The rsg is a dc 1800rpm 240bps.  I still have no pfc so that may be a
>> problem.  Anyway why is this doing this?  Any tips or suggestions
would be
>> greatly appreciated.
>> _______________________________________________
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>>
>>
>>
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