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Old 08-01-2009, 06:52 PM
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Harvey Harvey is offline
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Join Date: Jul 2009
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From where I sit, it seems we want a higher amplitude ring if possible. The frequency of that ring will depend on the battery and inductor combined resonance. Perhaps Hoppy or Milehigh can offer suggestions on methods of determining the battery capacitance so we can actually engineer a resonant circuit. My time is divided greatly over the next few days, but I will help where I can.

The Avalanche circuit inside the HEXFET serves to snub the ringing, but under certain conditions can actually exacerbate it when it encourages an increased current draw at the start of the spike but on the next cycles of the ring the Avalanche diode turns off for some reason. That would result in an increased field energy that dissipates in the ringing.

Rosemary, were any voltage measurements taken across the HEXFET? Did they ever exceed 1KV?

EDIT:
How can I measure the capacitance (NOT capacity) of a battery? - Yahoo! Answers
Chapter 9: Internal Battery Resistance
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Last edited by Harvey; 08-01-2009 at 07:39 PM. Reason: Added two links that may prove useful.