EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Time on June 20, 2014, 05:09:26 pm
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I am playing around with a simple 1:1 transformer that I made. It consists of 1 turn on the primary and 1 turn on the secondary.
I am charging up a 100 nF capacitor on the primary and letting it discharge through a resistive load on the 2ndary. It all seems normal with a little bit of loss in voltage but seemingly normal.
The strange thing that happens though is when I go to to discharge the capacitor through the transformer with an inductance on the 2ndary instead of the resistance. Quite a bit of voltage is loss, about half but it appears to ring out correctly. Why does this operate correctly under the resistive load (up to the V-s rating of the core) but not under the oscillating/inductive condtion?
The values I am using are 100 nF on the primary, 200 Ohm resistance, and 500 nH inductance.
I feel like the answer lies in basic knowledge of transformers which I don't know much about just yet.
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I think your answer might lay in the reactances of your inductor. The impedance (AC resistance at a given frequency) of your inductor might be much lower than the resistor's actual DC resistance on the frequency you discharge it on.
(http://www.uq.edu.au/_School_Science_Lessons/30.5.6.2.GIF)
Check the impedance here against frequency. You see that a resistor is pretty constant over the frequency range, while inductive reactance raises with frequency, capacitive reactance drops with frequency
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Cool, thanks for the response. I actually figured out what the issue was. My leads on the 2ndary were quite long with a small cross section. The parasitic inductance was significant at the ringing frequency of ~1 MHz. I figured this out by shortening them as much as possible and using some flat copper strips I had laying around.
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RazSlack : Plz send me a refrence for your graph Thanks