Re: A prospective s.s.t.c. input-synchronizer (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Wed, 20 Dec 2006 23:06:25 -0600
From: Steve Ward <steve.ward@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: A prospective s.s.t.c. input-synchronizer (fwd)

By anomalous Fr, do you mean the 14MHz noise?  That is very typical of
large IGBTs switching quickly, and is caused by the IGBT C-E junction
capacitance being charged through the stray inductance of the H-bridge
layout.  I battled that one for awhile, and eventually gave up, since
the coil still works fine, even with these harsh bursts of HF noise.
You have to be particularly careful about probing such noise, as many
times the scope might say they are worse than it really is.

Steve Ward

On 12/20/06, Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Wed, 20 Dec 2006 14:27:30 -0800
> From: K. C. Herrick <kchdlh@xxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: A prospective s.s.t.c. input-synchronizer (fwd)
>
> These are all excellent points -- and I may well have to re-wire some of
> my 5V-common circuits.  But my immediate problem is the anomalous Fr
> (see my other posting this date); when & if that's fixed, then I'll go
> after the "fuzz".
>
> KCH
>
> Tesla list wrote:
> > Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>
> >
> >
> >
> > ---------- Forwarded message ----------
> > Date: Tue, 19 Dec 2006 20:49:48 -0600
> > From: Steve Ward <steve.ward@xxxxxxxxx>
> > To: Tesla list <tesla@xxxxxxxxxx>
> > Subject: Re: A prospective s.s.t.c. input-synchronizer (fwd)
> >
> > Hi Ken,
> >
> > It may be either a grounding issue, or it could be possible that the
> > noise isnt real.  Putting ceramic caps on every IC V+ and ground
> > should normally be good enough.  Make sure that you dont have any high
> > currents flowing through the 5V ground.  If the 5V circuit is grounded
> > to anything else, be sure to use "star" grounding, and the 5V circuit
> > is just a branch on the star, and not the center.
> >
> > You probably already know all this, but you did welcome suggestions,
> > and hopefully it will get you started on figuring out the problem.
> >
> > Steve
> >
> > On 12/19/06, Tesla list <tesla@xxxxxxxxxx> wrote:
> >
> >> Original poster: Gerry Reynolds <greynolds@xxxxxxxxxx>
> >>
> >>
> >>
> >> ---------- Forwarded message ----------
> >> Date: Tue, 19 Dec 2006 11:28:54 -0800
> >> From: K. C. Herrick <kchdlh@xxxxxxx>
> >> To: Tesla List <tesla@xxxxxxxxxx>
> >> Subject: Re: A prospective s.s.t.c. input-synchronizer
> >>
> >> Chip, Steve Ward (& all)-
> >> ----------------------------------------------------------
> >>
> >> Hi Ken.
> >>
> >> Sorry for the delay.  I got slammed at work and didn't end up on the
> >> computer last night.  Here's the link.  It's just plain right now but can
> >> be fixed up to have html in it later. I just wanted to get it done.  Sorry
> >> for the delay again.
> >>
> >> Chip
> >>
> >> http://www.pupman.com/current/kcherrick/tch-synctest4a.jpg
> >> ------------------------------------------
> >>
> >> No problemo; looks perfect as-is.  And to all:  The above link is the replacement circuit for my synctest2.jpg that I'd posted
> >> previously on hot-streamer.  This one seems to work in the hardware.
> >>
> >>
> >> And Steve...in further response to yours of 12/18: My low-level EMI
> >> problem appears to stem from a 14 MHz transient that appears on the +5V
> >> bus every time the H-bridge switches.  I'm now trying to track that
> >> down.  Suggestions on that from >>anyone<< are welcome!!
> >>
> >> KCH
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> >
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>