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神经网络昆斯林的新闻组分类2006

Newsgroups: sci.electronics
Path: cantaloupe.srv.cs.cmu.edu!rochester!udel!gatech!concert!uvaarpa!murdoch!kelvin.seas.Virginia.EDU!dgj2y
From: [e-mail] (David Glen Jacobowitz)
Subject: Dumb Question: Function Generator
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Originator: [e-mail]
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Organization: University of Virginia
Date: Thu, 15 Apr 1993 15:52:52 GMT
Lines: 35


	I have a new scope and I thought I'd save a few bucks by
buying one with a function generator built in. After having it awhile
I noticed two things about the function generator. For one, there
seems to be a bias even when the 'pull-offset' is pushed in. That is,
I have to pull that know and adjust it to get a signal sans some
random 50mV bias.
	The other _really_ annoying thing is that the damn output
won't go below about 1V p-p. I am a student ( you may have guessed
from my previous posts ), and I often have to measure the input
impedances of various circuits I build.Many of the circuits have
maximum input signals of way less than 500mV amplitude and most have
input impedances in the 10's of Kohm range. The thing is, in order to
use my function generator I have to divide the voltage to some thing
reasonable. Then, of course, to measurethe input impedance of my
circuit I am going to have to throw in another resistor in series.
With the 50ohm output of the generator I could just ignore it, but now
with this little divider there I have to figure that in. It's kind of
a pain in  the ass.
	Is there any way I could make myself a little box that could
solve this little problem. The box would tkae the function generator
input, lower the voltage and give an output impedance that is some
low, unchanging number. I would want to lower the voltage by a factor
of one hundred or so. I could just build a little buffer amp, but I'd
like to have this box not be active.
	Any quick ideas. The scope's not broken. For other reasons I
had sent it to the shop to get repaired and they replaced it. The
function generator was the same way on that one, too.

			please help as I am feeling very stupid 
			today,

						dave 
						[e-mail]