[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Experimental Help - Terry?



Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Richard,

At 06:08 PM 2/21/2002 -0800, you wrote:
>
>Terry,list;
>
>There has been much discussion of late as to the radiation content of Tesla
>Coils.  We've known and accepted for a long time TC electromagnetic
>radiation.  But, now there's a new kid on the block - Longitudinal
>radiation.

"I" am far from convinced about the longitudinal radiation thing but I was
thinking about trying to bounce it off reflectors to see if it was coherent
or not.  Very precise antenna timing could be a possibility too.  Far from
easy...

>
>How do we prove it?  I've devised an experiment to measure TC instantaneous
>power. The rational is to measure the instantaneous and average primary
>power, exclusive of the SG, and simultaneously compare it with TC measured
>instantaneous and averaged power of the secondary.  If there is a power
>discrepancy between the power imparted from the primary versus secondary EM
>radiation, it needs to be accounted for.  A logical explanation of loss of
>power in addition to EM radiation is Longitudinal radiation.  

I have done some loss analysis with MicroSim:
=======
Hi All,

	Here is a list of the losses in a Tesla coil I had laying around.  I
forget the details but the numbers should be fairly typical.  I think this
is an LTR design...

Primary Neon Windings = 29 watts
Secondary Neon Windings = 21 watts
Filter Resistors = 92 watts
Primary Circuit Loss = 490 watts
Secondary Circuit Loss = 17 watts
Power to Arc = 127 watts
Total = 776 watts

Note that almost half the coil's energy is being burned up in the gap.
Capacitor losses and primary coil losses are comparatively low so the gap
is eating power like mad...

	Terry
============


 
>
>I make the assumption that all power radiated out through the TC secondary
>is equal to the power alternating through the base of the TC into the
>ground and back.  Furthermore all power in the TC secondary is derived from
>the primary by both magnetic and capacitive induction which are reactive,
>lossless transfers.  A very small amount or resistive loss may be present. 
>Further assumption is any longitudinal current does not involve base EM
>current.
>
>My experiment involves placing two large shunts in both the primary
>circuits.  I bought two old radio current shunts at a hamfest.  They are
>fortunately stamped on the side as to Amps vs millivolts.  They handle
>hundreds of amps and calculated resistance is milli-ohms and less.  Most
>any shunt if high enough power capacity will work, just keep R very small.

If they have a black plastic base with big brass blocks on the ends and a
funny metallic strip in between, they work very poorly at RF.  Been there
done that...  I would use current monitors like Pearson makes.  

>
>The idea is to measure and compare power simultaneously in both the primary
>and secondary base instantaneously and averaged.  With and without spark
>discharge, continuos and single shot.  My measuring instrument is a two
>channel TDS 210 DSO.  The experiment works.  Unfortunately, the 210 lacks
>the capability to simultaneously multiply one tracing by the other.  So, I
>can't obtain simultaneous power,(P = EI) or  (P = I^2R). I am aware some of
>the newer digital scopes have expanded math functions including power
>functions.  

If you can down load the data (needs the com card), you can put it into
excel.  Someone (like Ross ;-)) with Labview and a TDS 210 like I used to
have should be able to whip up a program to down load the data avoiding
using TEK over priced software.

>I believe our fearless moderator has one of these great
>instruments.  

I push the little button and the scope figures real time (or average or any
math function) power and stores it all to floppy disk in excel data files
or color scope captures. ;-)  Of course, it costs as mush as 200 cases of
beer =:O but they do everything.

>The TC base is tied to ground and is safe.  The primary
>current shunt seems to be safe, but should be left floating.  If concerned,
>a well insulated Pearson CT, 1:1 isolation transformer or fiber optic probe
>can be substituted and used with the big current shunt.

Yes.

>
>Can anyone offer advice on the experiment or better yet does anyone have
>measurement capability to get good data?

See the paper at:

http://hot-streamer-dot-com/TeslaCoils/MyPapers/modact/modact.html

You want to do basically those measurements.

>
>RWW
>
>P. S.  Terry, I've well insulated my Pearson CT.  It's bandwidth is 10 MHz
>with a huge amount of amps.  It can be used to measure a lot of other
>"unknown" TC parameters, example, HV current from HVTX to capacitor. 
>Actually, one of these low resistance current shunts can also be used here
>before the SG.  I haven't done it yet, but I want to put a very large HV,
>high powered, noninductive, very high ohm resistor (10 - 100 Mega-ohm)
>across the SG itself and measure current and voltage wave forms.  I would
>use the fiber optic probe here and NOT the Pearson.  Then there is NO
>guessing about power loss in the SG.  It can be measured and analysed. 
>Lower power loss SGs may be developed.
>

Yep!  I usually just run the computer models since I trust them and I don't
have to get out of my chair ;-))  But you can do real time voltage and
current in the gap and get power vs. time.  I would test your current
shunts against the Pearson before trusting them.  My shunts were pretty
hard to get to work at 500kHz.  Shunts usually don't like RF.  Reminds me
that I am still looking for a very high current Pearson...

Cheers,

	Terry