----- Original Message ----- 
From: "Chuck / Judy Burch" 
To: 
Sent: Wednesday, May 26, 2010 1:39 PM
Subject: PSD noise trouble


> 
> Thanks to everyone who made suggestions on eliminating high frequency 
> noise pulses produced by an analog switch, especially Karl Cunningham 
> and Walt Jung.
> 
> The problem was that high frequency switching pulses got through the DC 
> power bypass capacitors at the chip and propagated on the power supply 
> lines and ground over the whole circuit.  I was using 0.1 uF bypass caps 
> on each chip power connection.  When I used a 100 uF electrolytic in 
> parallel with a 1.0 uF film cap to bypass the switch's power connections 
> the problem effectively disappeared.  Other schemes might work just as 
> well or better - these were components I had on hand.
> 
> Some conclusions:
> 
> 1.  Bypassing PS connections at each chip is not overkill.
> 
> 2.  Ordinary bypass practice (0.1 uF to ground at each power connection) 
> is fine in most circumstances - but not all.
> 
> 3.  Try not to mix low level analog circuits with switching circuits - 
> and be very careful if you do.
> 
> 4.  Don't use that switching power supply you salvaged from a dead PC, 
> except as a source of parts.

Different signals are composed of different
frequency profiles. ( square, sine etc ???)

Different frequencies are handled in different ways.

Are you dealing with surficial currents or deep wire currents
When you deal with such noise ?

Are you able to speak and make yourself
understood too peoples not within
your skill field ?

I much prefer layman speech to engineering
speech. It is how i was trained.

The military used to be very good at
taking a 500 series university course
and condensing out the garbage
to present only the important stuff
to the high school drop out.

They do not teach us to communicate with
academia. Only with our own military kind.

Can any of you do that for me ??
Teach me your solution in terms I
can understand.

There needs to be a general noise attack
that will work against all kinds of noises.

I guess as a member of the PRP
they may very well want one dead
rather then let them communicate
with anyone outside the group.

Best regards,
geoff



> 
> 
> Thanks again,
> 
> Chuck Burch
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