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Calibrating I Transformer

 MG> The flyback transformer core should be reassembled after the windings
 are removed and then apply one or two layers of fiberglass tape to the core
 before applying the new winding. Or you could put a "spool" on the core
 with the windings on that instead, which would allow you to wind up several
 different ones for different current ranges. If a purchase of a core is 
 planned, I would suggest a #72 or a #75 mix ferrite material DO NOT USE
 POWERED IRON.
   For calibration you will need a 8 ohm 20-50 watt non-inductive resistor,
(audio dummy load) a audio generator capable of at least 50 Khz, preferably
100 Khz.  And a stereo receiver or audio amplifier with an output capability
of around 50 watts. Run an UN-shielded seperate pair of wires from the
audio amplifier output to the 8 ohm resistor running ONE of the wires 
through the center of the core. Connect the audio generator to the amplifier
and set it for the highest frequency that will drive the amplifier to its
rated output, this should be at least 50 Khz with a good quality unit. With
a audio voltmeter connected acrossed the 8 ohm resistor measure the A.C. 
voltage, assuming a 50 watt amplifier output the voltage would be about
20 volts, 20 volts at 8 ohms results in 2.5 amps flowing in the resistor. 
 Now you can adjust the turns on the core to result in a .25 volt or 2.5 volt
 or 25 volt reading on the meter connected to the winding which will be in
 proportion to the current flowing through the line that runs through the
 center of the core. The voltage scale you calibrate at depends on the
 sensitivity of the meter used. Or like stated before, you can forget about
 calibration and simply use it as a relative indicator, R.M.S. values in a
 Tesla coil mean very little, its not uncommon to have a rms value of 50 or
 60 watts and peak values of 500,000 or more on a fairly small coil.


                                Mark Graalman TCBA # 1399
                                mark.graalman-at-mediccom.norden1-dot-com



... Alias, Mark the spark
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