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Re: Tesla coil output voltage



Original poster: "JT Bowles" <jasotb@xxxxxxxxxxx>

actually you made it seem kind of hard.....heh. I printed out what you typed though, so I will actually do that later. Thanks.


From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: Tesla coil output voltage
Date: Sun, 27 Nov 2005 19:01:23 -0700

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>


Yes.

Set up a diode string to rectify the input high voltage. Then wire a string of resistors in series so you have a total of 6 megOhms. This allows your capacitor to slowly charge until it fires across the sparkgap.
Set sparkgap at .325 to .400 inch range.  It will fire once every -8 seconds.

Use a 3 inch dia. well rounded ground terminal (Xmas tree ornament?) to receive the spark.

Let it fire and carefully adjust the ground terminal for max. single pulse spark length. Measure this length in centimeters. Multiply this measurement by 26.5 kV/cm and you will have a very accurate measurement of your true output.

Next, veryify this and compare with the following equation. Using a borrowed meter (local tech school or university), or haul your primary/sec down to the school to measure it --- be sure to measure it at your resonant tap point. Measure the primary inductance in uHy. Measure the sec inductance in mHy. Convert both to Henries, then:

Vsec = Vpri (determined from spark gap setting) x 0.70 x SQR (Lsec/Lpri).

Terry has an archive with the voltage of various primary spark gap settings that I measured with a 30 kV power suppply. Use this voltage from the chart --- not the usual Erms x 1.414 value as this may not be correct. Cap charging potential is determined by the spark gap setting and not the xmfr (this assumes the xmfr has enough potential to charge the cap to fire across the sparkgap). If using a rotary gap, leave it unrunning and set with the sparkgaps aligned.

This will verify your test and confirm its accuracy within reasonable limits. --- It's that easy!!

The true output potential has nothing to do with breakrate or resonant freq of sec coil. It is determined by the physics equation:

Vsec = L * dI/dt

Plasma growth and sparklength from a running coil has a lot to do with breakrate and energy values, however, the true potential is independent of both.

Dr. Resonance



I need to know, for sure, what my coil produces.(voltage & current)

I can tell you all humidity, spark distance, breakrate of topload, and resonant frequency of secondary, and much more.

* currently its about 70% humidity
* my topload breaks out at 210 Hz
* unloaded secondary is 240KHz
* maximum spark distance is 15.5 inches
* topload is 10.5 inch diameter toroid, 3.5 inches thick
* topload is semi-smooth Aluminum air ducting w/ foil tape all over it
* no clue about output current

can you tell me, with this informartion what the output voltage is? Current would be nice too, but il need to measure that one somehow.

Borne coiler,
JT Bowles