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Re: Rotor BPS
Subject: Re: Rotor BPS
Date: Wed, 28 May 1997 20:10:13 -0400 (EDT)
From: richard hull <rhull-at-richmond.infi-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
At 12:17 AM 5/27/97 -0500, you wrote:
>Subject: Re: Rotor BPS
> Date: Mon, 26 May 1997 10:25:15 -0800
> From: Greg Leyh <lod-at-pacbell-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
>References:
> 1
>
>
>Gary Weaver wrote:
>
>
>> I have been thinking about building a rotor with 6 contacts on the non
>> rotating disk and 7 contacts on the rotating disk. This will give me 42
>> BPS
>> per RPM. Using a 1725 RPM motor it turns 28.75 RPM's per second. 28.75
>> x
>> 42 = 1207 BPS. Is that to many BPS?
>
>
>Yes, IMO 400 BPS is the point of diminishing returns for the arc
>dynamics.
>The rest of your available power should go into increasing Vpri.
>
>BTW, on those clever M x N gap arrangements, the _electrode dwell time_
>is usually the killer. If for instance your gap mentioned above has a
>9" electrode circle and 1/4" dia electrodes, then the dwell time will
>be over 600 usec, which is over 5 complete beat envelopes!
>
>Also, the prime power source will be shorted by the gap for a much
>higher % of the time -- in the above example, 75% of the time!
>
>% time shorted = (1/4"elect. * 2 * 42 breaks/rev) / (9"dia * pi)
>
>
>-GL
>
>
Greg is correct here. Tesla can be credited with this design. It is
logged
in the CSN in 1899 and Tesla used it prior to that time. I built a mock
up
of the gap and did the math back in 1990. Fred Glessner of Washoington
state actually assembled a beuatiful working model. Because of the
above
problems listed by Greg, the gap failed miserabley to work at all in
Glessners system. His break reate was over 2000 BPS as he power both
wheels
with counter rotating motors. This significantly reduces the dwell.
Still,
the rep rate was astronomical.
The best designs for one of these hummers would be 2 and 3 points, or at
most, 3 and 4 points. Also, one needs fairly large rotors both driven
at
moderate to high speed with very small electrodes. Best use is as a
maggey
gap. A bit much mechanics and alignment for the average joe for only 4
series gaps in the system. A form of simple series rotary is a better
choice for magnifier systems where simplicity, smaller wheels and lower
speeds are all the non-machining amateur can do.
Richard Hull, TCBOR