[Prev][Next][Index][Thread]
Re: re: Bipolar question ?MOSFETS
-
To: tesla-at-grendel.objinc-dot-com
-
Subject: Re: re: Bipolar question ?MOSFETS
-
From: harriman-at-metrolink-dot-net (harriman)
-
Date: Tue, 16 Apr 1996 23:30:39 -0400
-
>Received: from post.metrolink-dot-net (post.metrolink-dot-net [205.138.44.16]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with ESMTP id VAA02187 for <tesla-at-grendel.objinc-dot-com>; Tue, 16 Apr 1996 21:30:53 -0600
Hellow fellow solid state fans!
I've been using a capicitor/ resistor in series for snubbing, I've seen an
>alternative
>arrangement. However I didnot consider the turn on current, I assumed that the
>load
>the primary coil was inductive and therefore it would limit the turn on
current.
>But of
>course it is a transformer, so below resonance its an inductor, above resonance
>its
>a capacitor and at resonance its a resistor, that explains quite a lot, now I
>have to consider
>delibrately putting an inductor in series with the load (with a diode in series
>with a
>small resistor across it).
>I reckon that at 75v and 4A, I'll need 5uH to slow the current rise over 250ns,
>(14ohm
>resistor) does that sound right anyone?
There should be some leakage inductance in your primary? I would think.
Question ? How do you measure leakage inductance?
to avoid "shoot thru".
Drive FETS using a transformer three wires twisted together then wrapped
around a ferrite
donut. One for input, and one for each gate to source. Drive with a square wave.
Feedback is helpful, my coil (when
it works) goes off frequency as soon as you approach it and I have to keep
adjusting it.
Feed back is the only way! That is the real advantage of solid state coils.
Paul Harriman US