Re: tiny inductor with every bypass cap?

On Jun 23, 6:46=A0am, Joerg <notthisjoerg...@[EMAIL PROTECTED]
>
wrote:
> Paul Keinanen wrote:
> > On Sat, 21 Jun 2008 15:25:38 -0700 (PDT), bill.slo...@[EMAIL PROTECTED]
 wrote:
>
> >> On Jun 22, 5:52 am, Paul Keinanen <keina...@[EMAIL PROTECTED]
> wrote:
>
> >>> Are you sure that these are ordinary inductors or just a wire
through
> >>> a ferrite bead?
>
> >>> While the ferrite will increase the inductance, a suitable ferrite
> >>> material is also quite lossy at higher frequencies, reducing the
risk
> >>> for unwanted resonances with the capacitors.
> >> Sadly, you can't rely on this. I've had to put little resistors in
> >> series with ferrite bead to kill a resonance - admittedly at a few
> >> hundred kHz, where the bead doesn't look that lossy.
>
> > It would be quite hard to find material that would be lossy at such
> > low frequencies. For instance materials listed at
> >http://www.fair-rite.com/newfair/materials.htmstart
at 1 MHz
> > (material 31), while the common material 73 have significant losses
> > only above 10 MHz.
>
> I am lossy at low frequencies. Met my wife at an ultrasound company and
> she was quited stunned that my body would absorb even 3.5MHz to the
> point where she couldn't get a decent ultrasound image. Never seen it
> this bad before. She married me anyway.

One of my colleagues in the ultrasound group at EMI was a rower with
lots of muscle around the trunk - made him a lousy test subject for
ultrasound imaging. I played field hockey, which mainly builds up the
running muscles, and was much more transparent.

--
Bill Sloman, Nijmegen