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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.

96 questions with no upvoted or accepted answers
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41 views

Cortex-M DWT cycle counter inconsistent measurement

I recently discovered that it's possible to use a free running counter embedded in most Cortex-M4 cores to measure the performance of a chunk of code. I'm trying it on my LPC4370, where I want to ...
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47 views

What is a suitable hysteresis value and averaging period for a residential thermostat?

I've built a microcontroller based thermostat that I am using to control my home HVAC system. The actual programming and physical assembly has been straightforward. I'm using DS18B20 sensors, so I ...
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1answer
57 views

Measuring integrated current

I want to measure the amount of light striking a photodiode in a specific time window (about 1ms). In this window, we get \$10^6-10^7\$ photons, which get converted into electrons with about 80% ...
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93 views

How might the Lecroy HVFO High Voltage Fiber Optically Isolated Probes Work Internally?

I've been looking into these fiber isolated probes that Lecroy makes (http://teledynelecroy.com/probes/probeseries.aspx?mseries=537), and I'm curious how they're sending the signal over the optical ...
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107 views

How to properly store big values in parallel SRAM

For a project I need to determine the frequency and phase-shift of up to 16 channels. The frequency range is 0 to 3 kHz and the signalform is square. My first idea was to use the following circuit ...
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820 views

What is the accuracy of a thermocouple after calibration?

I'd like to use a thermocouple to create a general-purpose temperature probe. However, the accuracy is quite a bit lower than I want. Almost every source I look at (example) lists the accuracy of a ...
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141 views

Precision Tracking filter required

I don't mind if it's a band-pass or low pass filter (although I think low-pass will give a better result). Input operating frequency range is 100Hz to 1kHz. Input amplitude will be about 1Vp-p and ...
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1answer
65 views

How dual gyroscopes can be used to remove gyro drift?

I need to measure yaw/heading/azimuth correctly. Now, I have done with gyro with very strong filtering and the results are very low yaw drift and even when there is perfect calibration then there is ...
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30 views

How do I measure the fluctuation of a pulsed voltage of ~1700V?

The problem: See the little sketch. Starting from a high-precision DC power supply, I pass the voltage to low-pass filter and a pulser. This pulser pulses the nominal voltage of around ~1700V down to ...
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2answers
102 views

Measuring wow and flutter of a phonographic turntable with digital equipment

Old school way to measure: 3000 or 3150 Khz test tone from test record played back through phono cartridge/preamp into wow/flutter/drift meter and for turntable that has an electronic adjustment to ...
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1answer
41 views

What is the difference between residual phase noise and absolute phase noise?

Studying the characteristics of an oscillator with a phase noise analyzer, but I don't quite understand the difference between absolute and residual noise. Any help would be greatly appreciated
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125 views

Wrong measurement of DSO-5200A?

I'm using a DSO-5200A from Voltcraft and noticed the voltage measurement represented incorrectly (it is doubled). Any ideas how to reset this? Channel 1 (green) measures a (noisy) 5V and has a Vmean ...
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63 views

Amplifying pulse signals causing pulse lengthening problems

I am currently trying to design a circuit that would sense a voltage change at its input, convert that change into rapid "on"/"off" change at output and amplify same switching voltage to high current (...
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1answer
87 views

How can I make my measurements of full-wave rectified AC using an A/D match a Fluke meter on its DC range?

I am trying to measure the DC voltage of a full-wave rectified 60Hz AC signal using an A/D and have it match what a Fluke meter reads on its DC scale. My current approach is to take as many (16 bit) ...
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71 views

MEMS Microphone noise floor power level & audio noise spikes measurement

I have a circuit with a MEMS microphone and would like to be able to measure the audio noise spike contents and check the noise floor power level in the audio circuit. My intention is to connect the ...
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109 views

Power consumption measurement on the bench

I've been using the Atmel Power Debugger to sort out power consumption issues on some µController based circuits... and have been pretty pleased. Unfortunately, it's limited to a maximum of 5.5 volts ...
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49 views

Measuring resistance of switched load

I am in the process of designing a custom vaporizer. So the main coil with a resistance ranging from 0.2 Ω to 2 Ω is switched using a MOSFET shown in the circuit diagram below. ...
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1answer
51 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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173 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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255 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
99 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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0answers
83 views

How to figure the wiring of a 4 cable pc fan without frying it?

I have a 2 spare PC Fans which come with a four cable wiring and I would like to reuse them as ordinary fans (running at full speed all the time) outside a PC box, powered by a 12v source. ...
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1answer
1k views

Calculating AC Input Power

I'm making an AC to DC power supply that connects to mains. There's an AC to DC converter, buck converter and a smoothing LDO that outputs a DC controlled with pots. I'm verifying the supply, and ...
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89 views

Am I right about measuring current, and power

I have a meter that can measure: current, active power, reactive power and complex power. simulate this circuit – Schematic created using CircuitLab So, when I measure the four things: current,...
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449 views

Measure output AC voltage and current from a DC/AC inverter

As the title, I'm trying to measure and display 230VAC voltage and current from a DC/AC inverter on an oscilloscope. I don't know if I can proceed to measure them directly with these equipment: -...
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86 views

Why do we need voltage stabilizion in bridge measuring system with ratiometric connection?

i found in many weight scale reference designs that they use either low noise linear regulator or voltage reference for voltage stabilization. Why do we use them if ratiometric design cancel the ...
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1answer
57 views

About ideal floated measurement

In the book "Grounds for Grounding", p. 573, it give a figure: And it states: In a perfectly balanced circuit (i.e., \$Z_{H} = Z_{L}\$ and \$Z_{HG} > = Z_{LG}\$), where \$Z_{HG}\$, and \$Z_{LG}\...
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115 views

Equipment to measure strong constant (in time) and slowly changing electric fields

I would like to measure the electric field in the vicinity of an object of interest. I would like to have decent spatial resolution (i.e. be able to pinpoint a measurement to a point in space within ...
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39 views

current measurement in series-parallel solar panel array

I have a solar panel array wired in series-parallel. I know the voltages in a series network will be the average voltage, and the current in a parallel network will be the smallest contributing ...
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129 views

Why does inside of my sphere appear to be getting darker?

This a fully enclosed sphere containing a web cam, white led and photo resistor in exactly the geometric arrangement shown. The led glows dimly (via fixed dropper resistor). It runs at about 9 mA. ...
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1answer
146 views

How to estimate displacement error using accelerometer

I am using an MPU6050 and performing a double integration to obtain displacement, and this is to be placed in a vehicle that will be subject to about 2.5g. I cannot test it now, but how is it possible ...
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146 views

How to extract complex permittivity from a CV measurement?

I can choose from the following measurements: Z, theta (impedance and phase angle) R + jX (resistance and reactance) Cp-Gp (parallel capacitance and conductance) Cs-Rs (series capacitance and ...
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214 views

Do “True RMS” meters really do RMS if the input is a high frequency signal?

I'd like to measure the average of a signal which is mostly zero (less than a few nanovolts as best as I can tell) but may have occasional nonzero "blips" of maybe 20-100 nanoseconds (maybe 1V tall). ...
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395 views

Li-SoCl2 battery state of charge

I'm developing a data logger powered by Li-SoCl2 (http://www.100y.com.tw/pdf_file/02-SAFT-LS33600.pdf) battery and I have no idea on how to overcome the problem of estimating the residual charge of ...
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4answers
3k views

How to measure the temperature of a thin wire using a infrared (IR) thermometer?

I got a laser thermometer to measure the temperature of a wire for my science fair. However, when I attempted to measure the wire, it was too thin and I just measured whatever was behind it. How can I ...
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330 views

Need help with generating a bi-phasic current

I'm trying to generate a symmetric biphasic current pulse using a Grass S88 Stimulator. Here's a diagram: SG is a signal generator with two outputs, S1 and S2, which are generating a periodic pulse ...
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1answer
2k views

resistance measurement problem with digital multimeter

I accidentally caused a short circuit with DMM common lead while measuring 220 AC voltage. then when I tried to measure resistance it gives me a reading of 3500 ohm while there is no resistor ...
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2answers
46 views

Tektronix TDS3000 series max trigger rate

So I am making a testing stand for some equipment and I am using an old TDS3034C Tektronix scope for most of my measuring purposes. I've connected it to the computer via Ethernet and using PyVisa to ...
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1answer
108 views

Measuring current and internal impedance of current source

I am building a current source for an EIT project that I am doing. I have not reached the multiplexer part as I am still having issues with my current source. I am developed the current source as ...
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23 views

Can anyone explain dynamic gain measurement (2 tone test) to check for the memory effects in the system?

I have read in a lot of research papers concerning RF-Power Amplifiers that they tend to have memory effects. It means that the current PA output depends on the memory of the PA along with the input. ...
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1answer
30 views

Low power rectification of AC component of modulated current signal

I have a current source consisting of a 100Hz sine plus a DC offset: \$I=I_{DC}+I_{AC}\cdot\sin(2\cdot\pi\cdot 100Hz\cdot t)\$ with \$ I_{DC}\approx100uA\$ and \$I_{AC}\approx 1uA\$. I would like to ...
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25 views

measuring wireless (inductive) power supplies

I bought an electric toothbrush with a lithium-ion battery and wireless (inductive) charger. It came with one of those air/water jet flossing accessories, which also has a lithium-ion battery and a ...
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18 views

Hspice derivative measure

Is it possible to measure value of input voltage at a point when derivative of output voltage with respect to input voltage equals some value? P.s. The analysis done is DC. The input voltage is the ...
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22 views

Derivation of resultant standard deviation from individual standard deviation of an expression

Consider a problem: The total current \$ I=I_1 + I_2 \$ in a circuit is measured as \$ I_1=(150 \pm 1 ) A, I_2=(150 \pm 2 ) A \$ , where the limits of error are given as standard deviations , ...
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1answer
39 views

Contribution of solder parasitic to S parameter measurement

I have an antenna. I want to measure S-parameters of it using a network analyzer. The antenna has to be soldered to SMA cable for the measurement of S-parameters. After the calibration, will the ...
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28 views

How can I safely measure the output power of an RFID reader?

I want to measure the output power of a UHF RFID reader. I connected the antenna cable to one of the antenna ports of the RFID reader and to a spectrum analyzer (Hewlett Packard 8568B). There is a 10 ...
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47 views

Is it possible to measure impact force using Flexible PVDF Piezoelectric Film?

If it is possible , should i use integrator circuit first to hold the signal then follow it by other signal processing signals (amplification and noise filtering ) ? , knowing that i tried to connect ...
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74 views

How can I measure the actual magnetic strength of my electromagnet to compare against my calculations?

I am interested in building small scale electromagnets and I wanted to measure their actual magnetic strengths to compare against my calculations. What are possible ways to measure the difference?
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30 views

What test points to do for a switching system measurements?

I am working on a high-performance switching system. I the old ones there was no big issue in just touching a gate with an oscilloscope probe, but this time I have high voltage and very short (5nsec) ...
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1answer
51 views

differential measurement vs ground

I am looking to measure an incoming V vs ground with an ADC (MCP3424 or equal). The Vin vs Gnd can be anywhere from -1.5V to +2.0VDC. I looked at using an op amp with level shift, when I came across ...