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Twin coils 180 degrees out of phase : Weird happennings
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From: ESchulz531-at-aol-dot-com [SMTP:ESchulz531-at-aol-dot-com]
Sent: Friday, July 03, 1998 6:45 PM
To: tesla-at-pupman-dot-com
Subject: Twin coils 180 degrees out of phase : Weird happennings
OK,
I made two identical secondary. Same inductance 20 mh,
only 0.2% off. But my toriods are different. One is 5" aluminum
duct about 17 pf and the other is 7" about 22 pf. The primaries
are connected in series. Same inductance in each. Using
Medhurst formula I get a self capacitance of 11 pf. So the additive
capacitance would be 28 pf and 33 pf. So the frequency for each
coil should be 213 kHz and 196 kHz. With the coils alone I
measured them to be 216 kHz and 198 kHz.
OK that's all great. Now's the weird part
Now with the coils together I measured a 176 kHz frequency on
the 7" and 353 kHz on the 5". ? What in the world? By the way
176 * 2 = 352. I couldn't find any second harmonic on the 7" but
I found a 2,3,4 harmonics on the 5". The voltage on the 5" was 3
times greater than on the 7"
I measured the frequency with my o-scope and a RF generator.
The primaries in series and no primary cap. Normally my scope
only loads my coils by about 0.7% By load I mean change the
frequency.
I imagine everything will go back to normal when I get identical
toriods but what's going on here?
Thanks
Erik / Gradient