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Old 08-01-2009, 07:07 PM
witsend witsend is offline
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Join Date: May 2009
Posts: 1,881
Originally Posted by Harvey View Post
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?
Hi Harvey. If you're referring to our paper experiment - there were measurements but not recorded. To the best of my knowledge I have never seen voltage anywhere on the circuit that high - except when we tested from a utility supply source.

Harvey - please may I ask you a favour. Can you schedue the test protocol required to prove the effect with battery draw down. Or I'll try and do something - would you and any other qualified to do so please then vet it?
EDIT And yet again Harvey - many many thanks for the info re the MOSFETs. Much appreciated.

Last edited by witsend; 08-01-2009 at 07:10 PM.