Subject:
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Re: I have a Chalanging question!
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sun, 3 Oct 1999 17:08:14 GMT
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Original-From:
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David Kott <dakott@home.com!IHateSpam!>
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Viewed:
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828 times
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On Sun, 3 Oct 1999, josh wojnas wrote:
> ok I have to read a signal with almost no curent in the mv
> range and have it so a computer like the hb can detect it.
> now I dont mean just yes or no. I mean to watch the waves
> in the mv level and the circut cant distort it. couse dont
> amps just increse the hight of the wave??? from a 2mv
> signal PLEASE HELP!!!
This is a classic application for what is called an Instrumentation
Amplifier. An IA functions just like an ordinary Op-Amp, however it
typically offers close-to-rail-to-rail outputs and at least a very high
input impedance.
One would then use this amplifier as a preamp in your circuit. Since you
intend on using a Handyboard, I would suggest a single supply IA.
Here is Analog Device's IA selection tree.
http://products.analog.com/products_html/list_gen_4_2_1.html
Here's a selector guide from Maxim.
http://209.1.238.248/scripts/cSelector.exe/OP-AMPs/
Here's yet another from National Semiconductor
http://www.national.com/parametric/0,1850,2801,00.html
Intersil (formerly Harris Semiconductor) has a limited selection that
can be found here:
http://www.intersil.com/families/linear.asp
You would have to be more specific with your application for a less
ambiguous response. Information you might find yourself needing would
include the output drive capability of your device under test, and the
maximum frequency content of the signal you are measuring.
-d
Curiosity may, or may not, have killed Schrodinger's cat.
-townba
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Message is in Reply To:
 | | I have a Chalanging question!
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| ok I have to read a signal with almost no curent in the mv range and have it so a computer like the hb can detect it. now I dont mean just yes or no. I mean to watch the waves in the mv level and the circut cant distort it. couse dont amps just (...) (25 years ago, 3-Oct-99, to lugnet.robotics.handyboard)
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