Re: More Mini Coils (scopes)

From: 	John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: 	Friday, June 27, 1997 3:35 AM
To: 	Tesla List
Subject: 	Re: More Mini Coils (scopes)

At 04:47 AM 6/26/97 +0000, you wrote:
>From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
>Sent: 	Wednesday, June 25, 1997 4:30 PM
>To: 	tesla-at-pupman-dot-com
>Subject: 	Re: More Mini Coils (scopes)
>> From:   John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
>> Sent:   Tuesday, June 24, 1997 7:37 PM
>> To:     Tesla List
>> Subject:    Re: More Mini Coils
>>   A storage scope  captures and holds a certain signal on the scope 
>> for
>> study. It can not count the number of breaks/charges per spark unless you
>> have a custom made scope.
>Please explain. I have been examining secondary waveforms and their 
>correspondence to primary breaks. No proof has been presented that
>you can ring the secondary up and up with successive primary shots 
>using typical break rates either.

 If you are able to count the breaks/charges for a specific spark then you
are accomplishing what I am recommending. How do you explain the fact that
sparks from a TC vary in length if the wattage per spark is always the same?
The wattage is the major parameter that determines spsrk length.


>> If your storage scope can integrate several
>> signals to present a trace that represents the wattage summation of many
>> sparks it could be used for a watts per ft of spark rating.
>>   The input currents and therefore wattages to the TC transformer are in
>> surges from the utility company. Summing this data with an integrating
>> storage scope would give you one of the variables needed for a watts per ft
>> of spark rating.
>The average input to a coil itself is Ecp x BPS summed over time.
>I have already printed a table showing the lack of correspondence 
>between the wall plug and this figure for many coils. Peak energy per 
>primary break is Ecp. That is obviously going to vary enormously with 
>the use of async rotary gaps alone.
>     In my mini coil, "utility surges" and the like don't even enter 
>the picture. I am using _regulated_ power supplies and a well 
>defined static gap firing voltage (+- 4% measured).

  Your table showing the lack of correspondance between the wall plug and
the EcpxBKS is a good illustration of the number of TC's that do not
corordinate the necessary parameters for good design. With good design the
results may be even better than shown.

>>   The other variable would be the spark length which is varying in length.
>> The easiest way to average this variable is to use a horizontal continuous
>> spark from the toroid to a ground point, a controlled spark length.. 
>I refer you to Richard Hull's experiments with fans that show clearly 
>what happens to a coil that consistently produces long sparks in 
>still air. 


  If Richard Hull's experiments are producing continuous sparks  that are
horizontal from a toroid to a ground point then they could be called
controlled spark lengths.


>>   With these two variables determined it is then possible to calculate the
>> true watts per ft of spark for the coil.
>>   Note that measuring the wattage obtained at the input to the TC power
>> transformer and the maximum spark length obtained from the coil is not of
>> much value. This is because there is no way to find the wattage that
>> produced the maximum spark length. It is interesting to note that this type
>> of rating for Tesla coils has been used for years. The assumption was that
>> the wattage was the same for all sparks. This is obviously not correct
>> because if it was all sparks would be the same length for a certain coil.
>I submit that is not true for a highly repetitive situation. It takes 
>no account of air heating, ion clouds and the like IMO. Incidentally,
>I have seen a direct correspondence between wall plug consumption and 
>attached streamers using power meters. I have also seen power 
>consumption with no secondary sparks at all. It was this waste that 
>first made me wonder about using wall plug figures as a measure of
>power vs spark. That was several years ago.
>    Also, the largest coil I currently have set up produces a lot of 
>shorter air streamers when the target is placed a suitable distance 
>away, but strikes a hot arc to the target every now and then when it 
>reaches out in that direction (about 50% of the time) and when it 
>does, it is not a transient thing. It stays glued to the target for a 
>couple of seconds as the streamer rises by convection until the 
>connection is broken. At the break rate it runs, that corresponds to 
>200 dumps of the primary cap into the arc with a _very_ short 
>secondary ringdown. 2 seconds is plenty long enough to capture 
>dynamic secondary conditions during an attached arc. The secondary 
>goes absolutely quiet for well over 90% of the time between breaks.

  What are you referring to by "repetitive situation"?  Note that a
controlled spark length is a repetitive condition.

  With your largest coil producing a continuous stream  of sparks and now
and then a bigger spark can you explain what is causing the bigger spark?

  John Couture