Questions tagged [instrumentation]
166 questions
20
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13 answers
Why only sine waves?
I have already read a few EE texts where a sine wave is often seen.
Why is the sine wave often used as a test function for a circuit or a system? Why don't we use any other signal instead of sine?
Do we use sine waves as test signal because of the…
LECS
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11
votes
1 answer
What happened to all of the Dynamic Signal Analyzers?
Decades back there were at least half a dozen instrumentation companies offering Dynamic Signal Analyzers (DSA's). Not Spectrum Analyzers, but rather Dynamic Signal Analyzers. The main differences being dual or multiple channel input and frequency…
docscience
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1 answer
What's difference among impedance analyzer, spectrum analyzer and vector network analyzer?
Spectrum analyzer and vector network analyzer are the common instruments in the measurements of high frequency for electronic component. I think two of the most important issue in the high-frequency measurement probably is the impedance and…
BooliugooTusi
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7
votes
1 answer
Purpose of resistor across op-amp inputs
The following (from TI app note slaa414a) is an active bias-T that sums the AC and DC inputs to drive a load for the purpose of testing PSRR. What does the 100 Ohm resistor across the inputs do? Both inputs have DC paths without it.
65Roadster
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7
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3 answers
Why two inverters in parallel?
My teacher of Electronic Instrumentation's course presented me on an exam the following problem:
\$\hskip{75pt}\$
a) What is the importance of making the parallel between \$N7\$ and \$N8\$ logic ports for this circuit?
b) What is the effective…
Élio Pereira
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7
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4 answers
How do you measure nano volt order signals?
If you have a blackbox that gives you nanovolt signal in the output, how would you collect and process it? Signal to noise ratio is very low.
How do you filter the noise? Let's say the frequency range is 0-80Hz in that application.
What amplifier…
Silas
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6
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3 answers
4.75 digit count meters explained
What does it mean for a digital instrument when its readout is 4.75 digits "long'. And what is it like in comparison to, say a 4.5 digit meter?
Shemafied
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6
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4 answers
Designing an analog circuit that Fourier Transforms or Laplace Transforms an input signal
This is currently my pet project but I am a bit stuck on some problems.
First I'll go over my idea for the Fourier Transform:
The Fourier Transform is defined as
\$F(\omega)=\int^{\infty}_{-\infty}d\omega\ e^{i\omega x}f(x)\$
As it is difficult to…
firest
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5
votes
4 answers
Averaging thermistor readings
I have 9 thermistors arranged in a grid, and I want to average the readings from these thermistors without code (that is, average them in a circuit rather than reading all the values into a microcontroller and averaging within code) - for speed. The…
William Faust
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5
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0 answers
Potential issues with mounting tiny PCB directly to piezo transducer?
I am designing a very small signal conditioning daughterboard with the intent of mounting it directly underneath a cylindrical piezoelectric force device/"sensor" to rectify and filter the differential voltage generated across the two pins.
The…
Matt
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5
votes
2 answers
Gain-Phase measurement without dedicated equipment
I was wondering if it is possible to make Gain-Phase measurements without dedicated equipment like the venerable HP4194A or a more modern Bode 100.
As far as I understand, a Gain-Phase analyser is a device used to measure the transfer function of a…
Ken Grimes
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5
votes
4 answers
Why do LCR meter manufacturers give the details of measurement frequency to us?
When you want to purchase a DMM, more probably you don't see at what frequency the DMM you considered would work, but in the situation you're considering to purchase an LCR meter, manufacturers give you big details on the frequency of the LCR…
Roh
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5
votes
3 answers
What is the test voltage of a ohmmeter?
Ohmmeters don't appear to make LEDs conduct which gives overestimates in the resistance measured (tested with a R1//(R2+LED) parallel circuit). So what is the voltage they apply to the circuit, assuming it is conventional? I assume it depends on the…
Mister Mystère
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4
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3 answers
How to make repeatable Op-amp amplifier circuit
I did a simple op-amp based 100X gain single ended circuit. I tried to order 100 IC's and manufactured them. But found that out of 100 only 60 devices have same and expected baseline. What could be the reason for this variation and how do i improve…
Narashiman
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4
votes
2 answers
ECG circuit Pre amplifier
I am in the process of designing an ECG circuit to detect heartbeat abnormalities. I have two question regarding the AD8220 datasheet:
What is the function of the 2.2pF, 10pF capacitor, 10k, 15k resistors, and the diodes prior to the AD8220?
What…
Stephen
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