Mosquito Sound

[Jim Adney]

On Tue, 28 Sep 2004 03:55:16 GMT "Lewin A.R.W. Edwards"
<larwe@larwe.com> wrote:

Jim Adney wrote:

The scope will have an input resistance and capacitance. On Tek scopes
this is marked on the front panel. What does the NIC scope say?

It's not characterized on the front panel. I think it's probably in the
range ~150pF, at a guess, and my probes are designed for ~13-15pF input
capacitance. I'll look closer at the instructions (they are filed now..
didn't think I would be needing them immediately).

I doubt if it's as high as 150 pF. I believe the highest input C that
Tek ever used was 40 or 45 pF.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
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[Robert Baer]

Ken Smith wrote:

In article <41552C6E.661306FF@earthlink.net>,
Robert Baer <robertbaer@earthlink.net> wrote:
Larry wrote:

Hello,

I was hoping someone could send me in the right direction to find
information on a low frequency detector.
Either a low cost purchased unit, or the schematics to build one.
I am trying to detect in the 0- 30Hz range.
I appreciate any info, Larry

Use an opamp with low 1/f noise, and a loop antenna.

You didn't give enough details. How big does the loop have to be to do
the "0-" part of the range?

--
--
kensmith@rahul.net forging knowledge

Depends on the sensitivity you want.
Obviously, you cannot make a loop any where near 1/4 wavelength...

 

[Lewin A.R.W. Edwards]

Jim Adney wrote:

It's not characterized on the front panel. I think it's probably in the
range ~150pF, at a guess, and my probes are designed for ~13-15pF input

I doubt if it's as high as 150 pF. I believe the highest input C that
Tek ever used was 40 or 45 pF.

I say this number because googling around I've found a couple of people
using it with probes that are speced at "147pF". Oh well. In a few days
I'll be able to play again...

 

[Ken Smith]

In article <AOx1lzAGK8VBFwXa@jmwa.demon.co.uk>,
John Woodgate <noone@yuk.yuk> wrote:

I read in sci.electronics.design that Ken Smith
kensmith@green.rahul.net> wrote (in <cj7idr$nmi$1@blue.rahul.net&gt
[...]
(B)
The version you did is discontinuous near zero. In C++ you can redefine
the divide so that X/Y <==> cos(X/Y) yelding a nice smooth curve near
zero.

But you often don't want to *disguise* the 'divide by zero' because it
indicates a problem further up the code. Also, how can replacing, say,
136/0 by cos(136/0) = ?? make a smooth curve when the adjacent points
are cos(135/0.001) = 0.87 and cos(137/-0.003) = 0.89?

You are right. I messed up. I should have written something like cos(X+Y)

The whole point of C++ is information hiding isn't it? You want to hide
as much information as you can spread over about 50 *.h files so the
maintainer has no hope of finding the bugs.

This is part of the reason why there is much more code reuse in the
Fortran community than the C++ one.


--
--
kensmith@rahul.net forging knowledge

 

[Robert Lacoste]

Why not Lecroy ? They all have >1Gsps speed and huge memories, and more
importantly very good triggering capabilities. I will not exchange my
15-years old Lecroy 9350L for any TDS2000 or 3000... and probably not for
some TDS5000...

Cheers,
Robert

"David L. Jones" <altzone@gmail.com> a écrit dans le message de
news:459b0886.0409271506.60f0ace@posting.google.com...

larwe@larwe.com (Lewin A.R.W. Edwards) wrote in message
news:<608b6569.0409270852.38262d87@posting.google.com>...
more usful and practical in everyday use is a large sample memory. The
2000 and 3000 Tek scopes are both *very poor* in this area with only a
10KB on the 3000 series and a pathetic 2.5KB on the 2000 series. This
is terrible and actually makes the scope next to useless for lots of

[...]

For my money the Agilent 54600 series is the best value, most user
friendly, and most practical medium range DSO on the market. The mixed

I have a Tek TDS210 (among others) at home and two HP 54645D's at
work, and I love the 54645Ds. It was, and still is, a huge treat for
me to be able to capture an entire RF packet on the analog channel,
along with diagnostic strobes on the digital channels, then zoom right
in until I can measure the bit timing and inspect the signal shaping.

I assumed that deep memory was an innovation all DSOs received in
recent years, and that the reason my TDS210 had such a small buffer is
just because it's old. More fool me!

The problem is that fast sample memory is expensive. The Tek's have
1GS/s+, and to get a MB of memory at that speed is very expensive so
they just give you a lousy 10KB to keep the price down.
The low end Agilents are only 200MS/s, so for the same price point as
the Tek's you can get 2MB of memory instead of 10KB. Less effecvtive
bandwidth of course, but a lot of people don't need high bandwidth.
I think Agilent got it right on the low end models and Tek went the
wrong direction. Although the Tek 200/2000 series offer a good price
point for basic work. There is competition now though with Goodwill
entering the market.
Of course when you go to the higher end market both companies offer MB
and GS/s, but the prices get real silly.

Dave