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Re: Rotor BPS

Subject:  Re: Rotor BPS
  Date:   Fri, 30 May 1997 18:56:03 +0000
  From:  "John H. Couture" <couturejh-at-worldnet.att-dot-net>
    To:  Tesla List <tesla-at-pupman-dot-com>


At 07:05 AM 5/30/97 +0000, you wrote:
>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
>
>-------------------------------------------------------------

 In checking the input power to many Tesla coils on the Tesla List I
find
that they are underpowered. Increasing the BPS would only compound the
problem. Coilers apparently do not bother to do this important power
check
calculation. As a result they do not realize their coils are not
performing
well because they are under powered.

  John Couture