Re: L298 goes boom

Hey,
well I don't know enough about electronics or what how EMF works. I
do know what if I unplug a running fan from my 110V house outlet
there is a spark due to the difference in current etc. I assume this
is the same thing that occurs if a stepper is at idle (still on) or
running (still on).

I look at it this way, Dan makes the boards, he designes the boards,
he knows what he is doing, HE says NOT to disconnect a stepper when
the power is on (as every other place I have seen), I figure heck who
am I to disagree, hes gotta know what he is doing. Besides, why
chance it, its not that hard to switch off the power.

just my .02

tauseef

--- In CAD_CAM_EDM_DRO@y..., "exeric1" <exeric1@y...> wrote:
> Hoyt,
> It normally takes a lot to get me stirred up but you managed it.
> There is easily enough EMF generated when the magnetic field
> collapses to jump the gap as the contacts are disconnected. This
> forum is for "helping" people - not generating bad info that will
be
> expensive and discouraging to the people on it. May as well not
have
> a forum if information like this gets disseminated.
>
> Eric
>
> --- In CAD_CAM_EDM_DRO@y..., bjammin@i... wrote:
> > At 10:57 AM 8/4/02 -0400, RichD wrote:
> > >You are quite wrong. Any inductance carrying current will
generate
> large
> > >voltages when disconnected as the flux field collapses.
> >
> > Not back EMF, by definition. Also, it's not able to affect
drivers,
> as it
> > doesn't occur until disconnected from them. BUT, if you take
power
> off
> > steppers when connected, there *will* be a magnetic field
collapse
> that
> > puts voltage on the drivers ... and nobody even you has cautioned
us
> > against that! Therefore, you need to think these things thru a
bit
> more
> > before writing.
> >
> > Regards, Hoyt McKagen
> >
> >
> > Anti-virus request: Please do not add this email addy to address
> books
> > Belfab CNC - http://www.freeyellow.com/members/belfab/belfab.html
> > US Best MC -
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> > Hac ahac que haec, hoc, hoc, patui