I wonder if you have considered active low pass filters?

I have achieved some pretty impressive ripple rejection
by adding either a emitter follower capacitance amplifier
or a low pass op-amp.

I think your requirements would easily be meet with an op-amp.

  *
  |  __O    Thomas C. Sefranek   WA1RHP@ARRL.NET
  |_-\<,_   Amateur Radio Operator: WA1RHP
  (*)/ (*)  Bicycle mobile on 145.41, 448.625 MHz

http://hamradio.cmcorp.com/inventory/Inventory.html
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> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Mike Hord
> Sent: Sunday, June 22, 2003 7:42 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: Power supply recommendations?
>
>
> > > I'm not trying to be a smart-ass,
> >
> >Nor, am I. But this sounds like a band-aid job to me.
> >I would think that the circuit that can't endure a 5mV ripple is the real
> >problem.
> >That's where I would be investing my effort. Perhaps as ripple, perhaps
> >not,
> >but 5mV supply irregulariites can be induced or otherwise introduced by
> >many
> >unexpected means. Instead of having to deal with the snakes that will
> >appear
> >in the grass when the design is in real-world use, why not solve the
> >problem
> >at the root?
>
> </insert comments from original poster here>
> Believe me, I'd love to trash or redesign the circuit which needs the PS,
> but I'm
> afraid I don't have that option.  It's an expensive,
> off-the-shelf amplifier
> unit for
> signals acquired from electrodes implanted in the brains of lab
> animals, and
> we
> bought 5 of them without considering the ramifications (in fact, the
> problems
> which arose with these devices are in large part why I was hired).
>
> Normally, a small control panel would be purchased with each one of these,
> and
> those contain the necessary power supply.  However, those are $900US each,
> and we can justifiy spending $4k or more just to power these
> little things,
> when
> we already have the other bits we need (gain amp, filter, etc.) which are
> the
> expensive part of the interface panel.
>
> This leaves me with no real option but to build what I can to power these
> insane
> little buggers.  Grrrrrr.
>
> Mike H.
>
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