proposed measuring instrument

>>From hullr-at-whitlock-dot-comTue Jul 30 22:28:12 1996
>Date: Tue, 30 Jul 1996 17:26:03 -0700
>From: Richard Hull <hullr-at-whitlock-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Addendum-DC Tesla
>Since I hit the send button on the posting regarding DC electrostatics, I 
>have though of a few more tid-bits.  
>Many of my fellow engineers and even the more informed neophytes, just 
>have to feel that some sort of rectificaion is taking place in the Tesla 
>coil scenario I played out in the earlier posting.  Why guys!  Lets think 
>a moment.  I wonder if we were to account for all the losses and outputs 
>from a Tesla coil in "HOT SPARK MODE" if we wouldn't find the DC output 
>would swamp the AC output in relative power?  If this were the case, the 
>DC would be the "normal mode of operation for the sparking system"!! 
> How much of the ultra hot, slow discharges from a giant Tesla coil 
>toroid is DC electrostatic discharge energy?  There are, hopefully, 
>always more new questions than answers to old ones.  The RF and magnetic 
>energy in a disruptive coil is delivered in very potent and intense 
>bursts very far apart, spread out over a long time frame and the RMS 
>value of same is rather whimpy even in large systems.  What makes the 
>large arcs so white hot when the RMS energy per pulse is so feeble?  Will 
>we discover that the discharging, ultra large terminaled Tesla coil is a 
>DC device producing DC arcs with AC RF voltages and energies along for 
>the ride?
>Another observation.  A discharging tube coil or solid state coil (more 
>or less CW) will not produce the DC effect to any noticable degree!  It 
>appears, in fact, that it is down by a factor of 2-4 orders of magnitude 
>per unit RMS power input!  I have always spoken out for the disruptive 
>coil producing less RF and more DC goings on than the tube based system.
>I feel that this is due to the rather large instantaneous power per pulse 
>found in disruptive systems (often megawatts) as opposed to the tube 
>based systems ( rarely hundreds of watts).
>If it lights a luminous tube at range and has a bushy, quiet pale blue 
>spark with lots of corona, it is primarily tranmitting RF energy.  If it 
>is noisey and the arcs are white hot and infrequent, it is primarily a DC 
>producing system. 

>I hope to devise a quantitative method to check out some of these 
>concepts in future.  For those who wish to really understand the inner 
>workings of these systems in the future, I woud recommend a wake-up call 
>and study on the long languishing science of electrostatics!  I'm burnin' 
>th' midnight oil on this subject just now!

>Still tryin' to figger it all out....

>Richard Hull, TCBOR


If there was any money in Tesla coiling you could certainly quit your 
day job.  That post and its predecessor were excellent!

In thinking about what you said I have an idea for a tripod mounted  
field measuring instrument which might be useful in further analysis 
of this interesting phenomenon.  How about a pickup disc 
(electrostatic antenna) inside each of two side by side (like a pair of binoculars)
grounded large tin cans ( 1 gallon coffee tins).  
Behind each can you build a high voltage rectifier and accumulator 
capacitor (integrator), also encased in shielding.  Each rectifier will be a half 
wave, series rectifier with a really high front to back leakage 
ratio.  Each rectifier will be connected in opposite direction so that 
one can (antenna) will contribute to it's accumulating capacitor when the 
ambient field is positive of ground, and the other likewise when the 
field is negative of ground.  You run the outputs of each accumulator 
circuit to a single micro-milliamp d'arsenvol meter which has a needle that 
swings either side of a zero center depending on applied signal 

If you need more signal current you could work with 
multiples of two cans (4, 6, 8 etc) configured either in a square, 
or as more are added, a honeycomb pattern array.  The idea would be 
to equally space the positive and negative antennas as to get as 
equal pickup from the field being sampled by both polarities as 

If you set such a device up in the vicinity (beyond direct strike 
range) of either disruptive Tesla coils, or CW vacuum tube/solid 
state oscillator coils you should see two different results.  Near a 
CW oscillator driven coil I agree with your own conclusions from my 
own experience and predict that there will be little net meter 
deflection.  In the vicinity of a disruptive discharge coil the meter 
should swing difinitively one way or t'other, depending on coil 
phasing and predominant capacitor charging direction in the primary 
circuit of the T.C. at the moment in time.  The beauty (and 
usefulness) of this proposed instrument is it should indicate NET 
results after taxes.

My expectations ARE that this instrument MAY give very different readings
when tried on a disruptive coil without a toploading holdoff terminal, and with 
one with a really big holdoff toroid.  I think such an instrument could be 
beneficial to your present studies in electrostatics as they seem to 
apply to Tesla coils and I am tempted to assemble one to try for myself!

The results observed on a variable speed rotary break machine powered 
by the 60 Hz line could be interesting if the break speed is adjusted 
slightly positive of, at, and negative of synchronism speed with multiples 
of the AC line frequency.  The results might be even more interesting under this
condition, if the number of contacts per second on your break wheel are not
evenly divisible into the line frequency at the motor speed!

By the way, the diodes would have to be shottkys or vacuum tube, or 
otherwise RF capable high frequency, high voltage holdoff diodes.  I suppose
a pair of 1B3-GT's or 1X2B's would work well, each with a C-size dry cell
electrically floating with the tube as a filament supply,  (if anyone under 30 years
old doesn't know what these are, don't be ashamed to ask!).

It may also be possible to construct this device with moderate 
voltage shottky diodes and FET input op amps, nifty LED bargraph 
displays, or refreshing LCD panels, and don't forget this opportunity 
to employ an IEEE-488 (HP-IB) compatible bus connection, but while you 
young sprites are trying to figure out why your $10K in solid state 
instrumentation and computer equipment seems to be malfunctioning in 
the presence of a large artificial generator of real lightning,  I'll be 
watching my  $50 needle move in correct interpretation of the field 
I mean no offence to modern microelectronics technology, or its 
supporters,  it's just a matter of  'if the nail's a lot bigger, a simple, cheap, bigger
hammer may be more appropriate than a smaller, more expensive, 
possibly software driven,  admitedly smarter (and more delicate) hammer'.

Richard, your possible comments, and those of others are welcomed.

Regards, rwstephens