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Questions tagged [measurement]

Measurement is the assignment of numbers to objects or events. All measurements consist of three parts: magnitude, dimensions (units) and uncertainty.

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Difference between hybrid and resistive RF power splitters, and Frequency Response?

I am new into RF measurements, and have got a couple of questions regarding power splitters (hopefully common for all the models that exist in the market). What's the difference between resistive and ...
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1answer
231 views

Why do I measure 5V in this circuit when I should measure 3.3V?

I have an audio processor board that has a 5V -> 3.3V LDO. For some very strange reason, when I measure the voltage of the output of the LDO, I read 5 instead of 3.3V -- which by the way is a lethal ...
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86 views

What options are available for measuring grounded thermocouples?

I'm using 4 MAX31855 ICs to measure 4 K-type thermocouples and realized that 2 of my thermocouples have grounded junctions; I simultaneously also realized the MAX31855 is stated to not support ...
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69 views

Electronic detector to measure of distance? [closed]

I am not well known about electronic and it is my first question here, beforehand sorry for not qualified question. Let me try to explain what I am looking for: Is there chip or any another ...
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69 views

Measuring change in magnitude of electric current due to change in conducting material characteristics

I posted this in the physics section. I now think this might be more appropriate section for these questions. I am looking for answers to the following: What is the order of magnitude of change in ...
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69 views

optical path resonance distance measurement device, super useful for open source hardware if it would work [closed]

My head just tends to be full of open hardware and open manufacturing stuff, and one idea I have had for years and always wanted to try, but never could for want of access to an electronics lab, is a ...
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1answer
37 views

If I use a CAT 2 10x probe does my DSO need to be CAT 2?

I need to measure the harmonic distortion on a solar inverter (power output). I need to buy all the equipment from scratch and was wondering if my DSO needs to be CAT 2 rated if I use a CAT2 10x probe....
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49 views

Using a scope for an instrumentation and mains earth

When I make a measurement using a scope and observe transducer voltage output on the scope screen, I want to eliminate the noise as much as possible which is due to device and scope coupling or common ...
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85 views

What is the frequency shown on scope screen for this measurement?

I'm observing the noise of a voltage regulator output in AC coupling on a scope. Shown is a photo from the measurement: The FFT for the Vrms shows explicitly on the screen that there is around a 6....
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145 views

What's inside a reed switch that cannot be tested with a multimeter?

I'm shopping for reed contacts that are rated for 230V AC, because I don't want to use an always-on power supply just for a relay and a reed switch. This is surprisingly difficult, but I found this ...
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52 views

LTC1966 Sallen-Key post-filtering application question

Just a quick question about an application circuit in the LTC1966 datasheet. Figure 13 on page 18 shows a third order (when considering output resistance of the LTC1966) Sallen-Key filter, with a ...
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30 views

Effect of AC output impedance on a ratiometric measurement

I was planning to make a measurement with a ratiometric IC, so I will sense both the Vcc and the Vout from the chip as shown below. For cleaning up the noise and stability I also want to add a 5V ...
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68 views

How to translate high voltage 500 Vdc to 501 Vdc differential to low voltage 0 Vdc to 1 Vdc?

I have two high voltage nodes which I need to measure the differential voltage between. What I am thinking at the moment is the following... 1 - Use voltage dividers to probe the voltage at 1/1000, ...
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3answers
145 views

Practices for using a scope, scope probe and termination resistor for a proper measurement setup

In a setup, assuming a function generator has 50 Ohm output impedance and a coaxial cable has 50 Ohm characteristic impedance. Therefore to prevent reflection of a signal a 50 Ohm termination is used. ...
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1answer
42 views

Selecting the equipment with the optimal 10 MHz reference

In a larger testbench I have 5 synchronized instruments (signal generators, ARBs, VSAs etc). I am trying to decide which instrument to take as "master". I rule out the older/cheaper parts (Tektronix ...
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86 views

Is it appropriate to use a 300V RMS CAT I rated oscilloscope to measure 230V RMS of a power inverter?

Yesterday I decided to look at the waveform of my portable power inverter. The inverter specs are the following: Input: 12 V DC Output: 230 V RMS Rated power: 300 W I powered my inverter from a ...
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1answer
133 views

Did I ruin my multimeter with a current measurement?

I am trying to do a current measurement. Probably I accidentally put it it parallel instead of in series. What I tried before/after that (cannot remember exactly putting it parallel but might have ...
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72 views

Impedance magnitude and phase error - Mathematical formula

Today I read a paper on which there are the terms magnitude error and phase error relative to a comparison between measurements performed with a biosensor and with a benchtop electrochemical impedance ...
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162 views

Measure input capacitance of I/O pin

I'm looking for a simple laboratory procedure (and required equipment) to measure the input capacitance of each IC I/O pin. Thanks in advance.
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2answers
166 views

Negative Voltage Reference for Bipolar ADC

I am considering using ADS1258 - a bipolar ADC. It needs an external reference across REFP(+) and REFN(-). How do I generate precise -2.5V assuming I have +12V and -12V analog voltage rails? I can ...
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1answer
118 views

No output reading from Op Amp on Oscilloscope

So I have an inverting op amp (gain = -1) wired up, and it works with a DC signal. I checked the DC signal by measuring the input and output voltages with a multimeter which were 5V and -5V, ...
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1answer
39 views

Converting Uncertainty in dB to Relative Standard Uncertainty

Data sheets often give uncertainty in dB. If uncertainty is specified as a percent, I believe that means it is a relative uncertainty. Assuming the coverage factor is one, the relative standard ...
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3answers
69 views

How to measure tilt on a dynamic device?

I'm trying to instrument a vehicle component. I want to measure a component's angle during a drive cycle. The component has a single degree of freedom, it has a fixed axis. I'm trying to figure out ...
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1answer
116 views

RF signal generator, spectrum analyzer measurement questions

I want to test the attenuation characteristics of an RF filter I’ve built into a project, but do not have any experience using RF signal generators or spectrum analyzers. In all of the videos I have ...
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2answers
137 views

Building a DIY Oscillocope

I have decided that I would like to design a DIY DSO Oscilloscope, the idea has been in my mind for a while, I just haven't had the time to look into it, I am surprised as there doesn't seem to be ...
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111 views

What is the principal of Inductive Conductivity sensor?

What is the principal of Inductive Conductivity sensor which uses two coupled coils to estimate conductivity? Image Source I understand that the eddy current losses changes with the conductivity, ...
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42 views

What is and how to measure the tuning port capacitance of a VCO

I was asked to check all the specifications of this Voltage Controlled Oscillator. I might have an idea of how to measure all the parameters except for one, the Tunning Port Capacitance. I think my ...
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49 views

What is the use of making measurements using both forward and reverse currents? (Kelvin bridge)

For measuring low resistances using the Kelvin double bridge arrangement it was mentioned in our electrical measurement lab class that we should use both a forward current and a reverse current (i.e. ...
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2answers
143 views

How do current probes load a circuit?

It's usual to talk about loading a circuit when measuring voltage, with a voltmeter or with a voltage probe and an oscilloscope. It can be seen as putting an impedance in parallel to the element whose ...
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4answers
361 views

How do I measure very low frequency noise?

I'd like to measure low-level noise in the 1 Hz to 100 kHz range, for example at the output of a LDO. For higher frequencies a spectrum analyzer would do the job, but most only go down to the MHz ...
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1answer
67 views

Is it not recommendable to use a spectrum analyzer in its limit frequencies?

Suppose we have a spectrum analyzer whose range of frequencies goes from \$x \ \mathrm{Hz}\$ to \$y \ \mathrm{Hz}\$. Is there any problem that could arise from measuring signals that are near those ...
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2answers
118 views

Can any meter be PT connected?

I have an EE background, but am new to metering hardware. Looking at metering equipment for high voltage measurements (up to 6.6 kV), it seems most only go up to 480 V, even when classified as ...
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86 views

Measuring temperature of fluids inside a glass tube

Suppose I have some experiment with some fluid (e.g. water or milk) flowing through (or just residing in) a cylindrical tube made of glass. What would be a good way to "non invasively" measure the ...
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40 views

Measuring small strain with strain gauge, how nullify errors?

I have a similar circuit like https://www.egr.msu.edu/classes/ece480/capstone/spring15/group05/uploads/4/7/5/1/47515639/ece_480_app_note_justin_bauer.pdf 2. page bottom Wheatstone bridge: 2x 350 ohm ...
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1answer
61 views

in-amp for strain gauge

I'm working on a project where I should send an overload signal if the strain is bigger than 40 ppm. So far I found this answer: Strategy to balance a Wheatstone bridge for strain measurement The ...
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2answers
135 views

What to look for in an isolation transformer?

What do you want from an (isolation) transformer besides it having the minimum voltage/current/power(/frequency?) specs that the to be isolated device needs? Does it matter whether the transformer is ...
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1answer
137 views

How do you know that an oscilloscope is displaying the actual waveform?

As oscilloscopes get faster and faster, when designing a new scope how do you know that what it's displaying is the same as the actual waveform? For the fastest scopes, you don't have something ...
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2answers
56 views

Period Measurement

I am reading a book about the measurement in communications. There are a lot of information about how to measure frequency and period of signals. OK, i have understood that we should measure the ...
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1answer
81 views

Dictionary: is PWM precision the same of PWM resolution?

I have an issue in identifying the meaning of PWM precision. I've always talked about PWM resolution, and to me seems to be 1/2^(n-1). Is the precision of the PWM just prequency precision? Or is the ...
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454 views

Why is this the maximum dynamic range in a spectrum analyzer?

In Keysight's popular AN 150 there is a plot of noise and harmonics amplitudes versus the level of the input signal at the mixer (page 57). It's stated there that the maximum n-th dynamic range is ...
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104 views

Output impedance of a 4mA to 20mA current loop

I have the most basic of basicness circuit. The implementation is a XTR115UA IC with a 40µA - 200µA input (based on sensor voltage) which is amplified to the desired 4mA to 20mA current in the current ...
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1answer
38 views

Detecting velocity in a specific threshold [closed]

I have three velocity sensors that are axis in 3D. I would like to know the best method to do basic ON/OFF trigger.. I'm thinking of a hystersis control, is there a method that can detect if the ...
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83 views

How to measure remaining lithium battery charge accurately (destructively)?

I want to measure the remaining charge in batteries and my requirements may be somewhat unusual. I do not need to preserve the charge left in the battery and it doesn't have to be quick. All I want is ...
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31 views

Techniques for probing circuits that would normaly be covered by a heatsink

I have a circuit board I have to probe and measure to first debug and then later on verify performance. The circuit board contains a power amplifier that requires a heatsink in order to keep the ...
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2answers
137 views

Measurement of total AC resistance (including radiation resistance) of a coil using LCR meter

If we measure AC resistance of a coil using an LCR meter (or impedance analyser), does it include both ohmic resistance and radiation resistance? I understand that the radiation resistance is ...
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2answers
197 views

Measuring crystal drive strength without a current probe

TL;DR Is there a means of measuring the crystal drive level reliably using voltage measurements (even with a differential voltage probe)? Background: I am attempting to measure the crystal drive ...
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1answer
52 views

Is the carbon-zinc battery that I am characterising overloaded? Using HPPC

I am trying to characterise a 9 V battery using a pulsed load measurement. The battery is a 9 V zinc-carbon eveready super heavy duty. The load is a controllable constant current source. When I ...
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29 views

Can I use a scope probe to connect a signal generator to a generic circuit?

It's an exam question stated as in the title. I don't know how to analize the problem. As long as it's a BNC to BNC coaxial cable anything goes I think, but I don't know for attenuating probe or ...
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54 views

Question about a trigger input of a modern ARB/VSG (Vector Signal Generator)

Given a common setup: The green box is a PCB mainly consisting of a data acquisition device (ADC+RF frontend) which is controlled by a Spartan-6 FPGA. The ADC & FPGA use a clock from a Tektronix ...
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232 views

How does capacitive coupling work for measurements

The context is the measurement of engine speed on a vintage car that uses a classic Kettering ignition system. Essentially, a voltage pulse of tenths of kV is generated on a high tension (HT) lead. ...