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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51 views

Current to voltage converter and voltage follower

I am designing a current to voltage converter for my sensing device. followed by a voltage follower or a buffer. by varying vcc, so that i can achieve sensitivity of my circuit. do i need to have same ...
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1answer
55 views

Getting Agilent USB GBIP Adapter to work with NI-Visa or R&S GBIP over USB with Agilent Visa

This Visa/IVI jungle is pretty much a desaster. Not enough that each package contains GBs or data, they also cause problems when installed in parallel (one example: https://www.mathworks.com/support/...
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1answer
52 views

Measuring resistance

I would like to measure the resistance of a resistor in the most basic way by running a current through it and measuring current and voltage. I understand that I have basically two options to place ...
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2answers
171 views

VSD (Inverter) current measurement on 3 motor phases

I'm working on a project to build a rig for testing various sized Variable Frequency Drives (VSD's / inverters), the kind that you'd use to run a squirrel cage induction motor. The range would be from ...
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1answer
182 views

Problem with mesuring value from current sensig pin on VNH2SP30

I connected the Monster Motor Shield (based on the VNH2SP30) to the Arduino Uno and successfully drive the engine, but I can not measure the value from the CS pin on this board (the voltage at this ...
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2answers
814 views

Why IR remote waveform is a saw-tooth or am I measuring it wrong

The measurement circuit is as follows: simulate this circuit – Schematic created using CircuitLab The waveform looks like this in my measurement: Is this because I'm measuring it wrong and ...
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1answer
145 views

Mains frequency noise components

I'm currently doing a lot of work in measuring transfer functions of circuits. One thing that crops up a lot is mains frequency noise: As you can see there is a huge 11 dB leap at 50 Hz, followed by ...
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0answers
87 views

What does a multimeter read when you measure unstable DC-voltage [duplicate]

When I have a Fluke True-RMS multimeter. Does the meter measure DC-RMS voltage or the average voltage?
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1answer
338 views

Measuring an AC-voltage at the ouput of a full bridge rectifier

I've a full bridge rectifier and I put the following function into it: $$5\sin(100\pi t)\tag1$$ So, at the output I get: $$\left|(5-2V_d)\sin(100\pi t)\right|\tag2$$ Where \$V_d\$ is the voltage ...
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2answers
42 views

Systematic high frequency error in TF measurements

Full disclosure, I've asked a very similar question before which didn't have much success as it was too specific. However I want to try again by restricting the scope of the question. Scenario I'm ...
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2answers
140 views

Multiplexing of resistance measurements

I'm designing a circuit that requires me to measure three low value (8-60 ohms) resistors with a hard wired common connection on one end. My ADC doesn't have enough inputs to measure all three at once ...
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2answers
144 views

Is this LED slow, or am I measuring it incorrectly?

I am attempting to turn white light LEDs on and off at a very high speed. Here is a link to the LED being used. https://www.superbrightleds.com/moreinfo/through-hole/5mm-white-led-75-degree-viewing-...
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56 views

HF current measurement

I have an assignment, where i'm supposed to (sort of accurately) measure the current drawn by a SIM-card, in the different phases it can operate in. The current is by no means DC, as the SIM-card ...
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1answer
176 views

Enabling external reference to HP/Agilent Signal Generator (8648C)

What is the proper way to use an external 10 MHz clock signal for an HP/Agilent signal generator (in my case: 8648C)? With my Tektronix, Rohde & Schwarz devices, internal/external reference has ...
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3answers
704 views

Easy way to estimate the power handling capability of an unknown transformer

I have quite a lot of old scrap mains step-down transformers (220V-240V 50Hz), salvaged from old equipment during 30+ years. Although I religiously marked the primary terminals of all of them as a "...
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2answers
2k views

LTSpice: How to use .meas command to find the fundamental frequency of non-sinusoidal signal?

I want to find fundamental frequency of a periodic signal (non-sinusoidal) in certain time window using the .meas command in LTSpice. I was using the following ...
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2answers
121 views

Probes gives different results

I discovered an "funny" thing today. I had used a GW instek probe GTP-150B-4 150Mhz in 10x mode and documented the result. Today I noticed in the testing department that what I've measured doesn't ...
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359 views

How to connect bathroom scale (arduino+hx711+spark load connector)

Im a new user in the electronic world. I tried to hack my bathroom weight scale but no success. There is a great tutorial which I followed: https://www.youtube.com/watch?v=iywsJB-T-mU my parts: ...
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2answers
64 views

Thermal considerations for electronic measurements

Background Generally components behaviour changes with respect to temperature, e.g. a resistors resistance is a function of temperature, as is the saturation current of a BJT. When putting a ...
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1answer
1k views

AC relay coil current calculation

I am trying to calculate the current required to energize and hold a 24 VAC relay coil while switching no load. I did the same for a 24 VDC relay coil using ohms law which is very simple and matched ...
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2answers
252 views

How to effectively downscale input voltage of a device?

Oscilloscopes let us measure input voltage in a variety of input signal ranges (either AC/DC, +/- 500V or Gigahertz's of frequency). I am wondering: how they make it happen? Say, an oscilloscope has ...
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1answer
217 views

Measuring Vackar Oscillator Output Amplitude and High Frequency Effects

This is somewhat related to my previous question regarding why I wasn't seeing a clamp biasing effect with my JFET Vackar oscillator. I think I figured it out and I'm wondering if you guys agree. ...
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71 views

Measurement setup for power line spectrum

I've come across a setup for measuring AC power line spectrum. Here is the spectrum graph which shows 60Hz and harmonics in a power line voltage: And below is the setup and wiring for this ...
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2answers
412 views

winding resistance measurement - thing from literature that i dont understand

There is a thing that i dont understand... If i measure winding resistance of the transformer primary winding - will result depend if secondary is shorted or open? If yes - why? I also attach the ...
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1answer
31 views

Max allowed measurements error

Since it's not possible to know with 100% accuracy about what's going on in a circuit and its components, and I have to trust my multimeter on measurements, what's the usual approach to managing ...
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2answers
61 views

Insulation resistance tester: orders of magnitude difference in measurement depending on connection polarity

https://youtu.be/eGjd7HoYyz8?t=115 The man on the video is measuring a transformer's insulation resistance, the resistance measurements are very different depending on how the meter is connected: ...
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1answer
1k views

Converting negative DC voltage to positive equivalent

Requesting some input on this topic which has already been discussed (partially for my requirement) here: Negative to Positive Voltage Converter I also have a positive-only display and I need to ...
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3answers
241 views

Why does the capacitance of ceramic capacitors change with test measurement voltage change?

I faced a problem of measuring capacity in ceramic capacitors. Measurements did with Smart Tweezers ST5S. It has two output voltage levels that can be selected: 0.45 Vrms and 0.9 Vrms. The capacitor ...
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0answers
80 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
97 views

Mistake in reading a rms voltage

I got a really strange result. I've build a full-bridge rectifier with a capacitor filter. And I used the following values \$\text{C}=500\cdot10^{-6}\$ and as a load \$\text{R}=1000\$. The maximum ...
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1answer
913 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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1answer
134 views

Measure duration of a non periodic message on FPGA with VHDL

I'm trying to measure the duration of a non periodic signal(message) on FPGA, as below : I want to measure the duration of the measured signal by counting the number of reference clock's period. I ...
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1answer
87 views

How can I tell from a datasheet if a thermocouple amplifier IC will work with a grounded thermocouple?

There are several different solution available for thermocouple amplification such as the MAX31856, AD8495, and LTC2983. Some of these support grounded thermocouples (AD8495) and some don't (MAX31856)....
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88 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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1answer
89 views

Question about the RMS value of the real input power

I've the following circuit: simulate this circuit – Schematic created using CircuitLab I know that the relation between the input voltage and the input current is given by: $$\begin{cases} \...
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1answer
68 views

High impedance divider measurement with instrumentation amp

I'm having trouble with getting an accurate measurement with this circuit and I was hoping for some more help. See the circuit, which I have breadboarded and am testing. I step down a voltage through ...
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1answer
94 views

What is this strange artifcact on my inductive element?

I was looking at the Voltage/Current on an old inductive element, without any other components in the loop, and I got this weird artifact. Sadly, the xml file I saved was corrupted, so i had to ...
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1answer
237 views

Does the AD8495 thermocouple amplifier allow for grounded thermocouple probes?

I recently purchased a MAX31856 thermocouple-to-digital chip for a project. However, I discovered that the chip does not support grounded thermocouples. I am looking for an alternative and the AD8495 ...
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2answers
82 views

DFT: Designing a Schematic / PCB to allow measuring resistor values

Is there a standard method of schematic design to allow measuring individual resistor values on a PCB? Useful for general debugging, validating a new PCB shop, etc. Because, if part of your circuit ...
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1answer
95 views

Looking for an AC current sensor for less than 10A measurements

We are building a voltage and current acquisition system using NI hardware. While voltage measurements are done directly using the NI IO Module, current measurements need a sensor. We have a 100A (...
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1answer
132 views

The book I want that you may know about Electrical Measurements [closed]

I'm looking for the book that online version could not be found on the internet. The book called Electrical Measurements: Examples and Problems, 116 pp., Nicosia, 1999. by Ismayilov, Khalil Abbasoglu ...
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2answers
79 views

Calibrating DAQs

I'm using some of National Instruments' DAQs for some measurements, but their calibration is slightly off. To work around this I am hoping to factor in any imperfections into the measurements such ...
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4answers
2k views

4-terminal shunt resistor [duplicate]

What is the importance of a 4-terminal shunt resistor? What is real purpose behind using two seperate terminal for the voltage measurement across the shunt resistor?
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1answer
250 views

Connecting a spectrum analyzer without DC block

I have seen many spectrum analyzers with the warning on the RF input port: “!!! Avoid electrostatic discharge and DC voltage !!!”. Out of precaution I always connected my signal source with a DC ...
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6answers
2k views

What sensors to use to read gym machine selected weight [duplicate]

I'm trying to find a set of sensors (to build a solution) to determine how many weight blocks an athlete is lifting on the weight machine like this: I already tried this solutions: Put RFID tag on ...
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4answers
342 views

Reading dynamic resistance values over a wide range

I'm trying to measure a material which might fluctuate between 500-100k Ohms with an ADC (e.g. an Arduino or Raspberry Pi with something like the MCP3008). I'm a novice with electronics, and my go to ...
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2answers
714 views

Measuring 0.1mm accuracy of very short distance (< 5 or 10mm)

I need to measure a very short distance (< 5 or 10mm) of a rotating shaft which will eventually move to one side by a few mm. I would connect this to an Arduino or similar. Could someone recommend ...
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3answers
335 views

Distortion Elimination with Differential Transistor Pair

Most of you know that incorporation of negative feedback within amplifier is one of major considerations when designing a hi-fi amplifier. Till now, I have only dealt with differential transistor pair ...
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4answers
290 views

How are high-speed circuits tested if test equipment doesnt exist?

How was testing done for Ghz to THz range circuits and devices before fast enough scopes and frequency counters existed?
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92 views

A question about differential ended settings for single ended inputs

Reading this documentation, what could be the reason to use 10k if one uses differential ended input settings for signal sources?: I dont know why they recommend 10k but I had 6 channels going to ...