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Re: coil running of car battery(s)?

Original poster: "Black Moon" <black_moons@xxxxxxxxxxx>

Iv used fets before, and understand most things about them, but could someone please explain what avalanche is exactly? (maybe offlist if terry objects to it being onlist)

From: "Tesla list" <tesla@xxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: coil running of car battery(s)?
Date: Tue, 25 Jan 2005 08:11:33 -0700

Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>

Hi Derek,

Well unless they have some protection or they have come up with a new gate
material yep that's a quick way of killing them one very narrow spike will
do it on the gate.
The older power fets did not even like a spike on the output.  I assume this
one avalanches in a controlled fashion just soaking up the joules over the
whole die.   Still 1/2J is impressive assuming I did not miss read the spec.


----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, January 24, 2005 4:21 PM
Subject: RE: coil running of car battery(s)?

> Original poster: "Derek Woodroffe" <tesla@xxxxxxxxxxxxxxx> > > >Hi Derek, > > >I was curious about the circuit so I checked it out. I was initially > concerned because it has no snubber > > >across the FET. So I checked the data sheet out for the device. I was > impressed by its large safe operating > >area and 0.5J single pulse avalanche energy capability. Truly a transistor > that's hard to kill. (but not > >impossible) > > >Robert > > Robert, > If only I have killed many of them, usually from spikes in the gate, they > are very susceptible to HV.. > > Although the circuit is similar to the one I used, being 30+ I have actually > used the good old 2N3055, which is apparently much easier to kill, maybe its > my experience, but i've only killed a couple in that circuit, and most of > them are from shorts whilst playing, not "in service". I do have a 4nF cap > and a reverse diode across then though. > > Cheers > Derek > >