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Re: [TCML] Measuring secondary current
I wonder how you got 96 V for the secondary voltage. The equation for
secondary voltage is
Isec * 2 * Pi * f * Lsec
Plugging in 500kHz for f, 0.4A for Isec and 13mH for Lsec I get
about 16 kV, which is enough for small sparks.
Secondary currents are low, so you should be able to measure them
by putting e.g. a 1 ohm resistor between the base of your secondary
and ground and measure the voltage across it.
Udo
On Thu, 30 Aug 2012, Jim Lux wrote:
Feeding the ground wire from my secondary through the center of the
newly-minted CT and turning on the coil, I put my oscilloscope probe
across the 14.7k ohm resistor (actually a 10k and 4.7k in series) and
fired up the coil.
The result is a nice 5.6V peak-to-peak sine wave at the ~500kHz resonant
frequency of my secondary...
So 5.6/14.7k = 0.38 mA
110:1 turns ratio implies about 408mA secondary current...
That would be a bit strange, since I'm feeding the primary with 24V @ 2A
... I doubt I would get any arcs at all if there was only 96V at the top
of the secondary (and any more voltage would imply the impossible).
There's still the issue that when I calibrated the current transformer
against a known voltage/current source I got a very different conversion
factor (2mV per mA through the wire under test).
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