I have the same motor out of a treadmill, 3hp on a variac to a bridge, smooth. I had a 25KVA pig, but turned out to be shorted. Guess when it fell off the pole. Oh well , one step at a time.
-----Original Message-----
From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of David Rieben
Sent: September 13, 2020 12:31 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Asynchronous versus synchronous gaps, was Old Post
Hi Jan,
Yes, thank you for highlight a very important aspect of async SG operation that I failed to mention in my posting. Higher bps rates that are several times the mains frequency, in addition to to generous power, are essential for optimal asynchronous coil operation. ~350 bps seems to be the approximate “sweet spot” for my pole pig powered and async spark gap driven coil. I use a DC permanent magnet motor (from a treadmill, I believe) for my rotary gap drive motor, with a rectified and variac controlled input to affect basically infinite speed control of 0 - 3500 rpm. Since there are 8 flying electrodes on my rotary disc, and the motor is rated for 130 VDC and 3500 rpm, I typically set my speed control variac between 70 and 75 on the dial for the “sweet spot”, with the variac set to deliver 0-120 volts (not 0-140 volts) output.
David
Sent from my iPhone
> On Sep 13, 2020, at 9:58 AM, jan@xxxxxxxx wrote:
>
> -----Original Message-----
>
> From: Tesla [mailto:tesla-bounces@xxxxxxxxxx] On Behalf Of David Rieben
>
> Sent: September 11, 2020 7:01 AM
>
> To: Tesla Coil Mailing List
>
> Subject: Re: [TCML] Old post
>
>
>
> Hi Shaun, Steve,
>
>
>
> Although synchronous firing (w/LTR tank capacitor) can be quite advantageous
> for the rather limited available? power with a typical NST driven spark gap
> coil system, from personal experience, I have found the output can be just
> as impressive with asynchronous spark gap operation and higher bps ranges w/
> a smaller than resonant tank capacitor with the more copious available power
> with PT or pole pig driven spark gap coil systems. And it?s a whole lot
> easier! ?
>
>
>
> Just my $.02,
>
> David
>
>
>
>
>
> Hi,
>
> as has been pointed out, asynchronous gaps are very effective att higher
> BPS, but at low BPS synchronous are better. At higher BPS some bangs will be
> a bit off in timing, but others will be at the right point. The energy left
> in the ballast after less successful bangs will be used in the next bang, so
> it all evens out over time. But at one bang per half period, the timing is
> very critical and a synchronous gap with phase control is a must.
>
>
>
> I have done some measurements and discuss these issues at my web site
> https://www.sthlmteslacoil.se/measurements.html
>
>
>
> So successful coils could be designed with either type of gap, depending on
> the BPS. But more important is the resonant charging concept. A good
> resonant design could supply three or four times the energy compared to an
> arbitrary design. I discuss these issues also at my web site.
>
>
>
> Regards,
>
> Jan
>
> Stockholm, Sweden
>
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