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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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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
142 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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0answers
46 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
127 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
355 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
772 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
92 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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0answers
244 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
61 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
866 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
149 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
154 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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30 views

How can I create common mode interference for this setup?

I have a measurement setup where a battery is coupled to a single-ended data-acquisition board though a coaxial BNC cable. This board is powered and monitored by a laptop PC through a USB cable. The ...
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0answers
54 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
292 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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3answers
178 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
74 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
71 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
610 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
107 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
67 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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0answers
85 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
66 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
56 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
93 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
183 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
75 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
77 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
117 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
74 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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1answer
165 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
247 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
558 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
279 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
273 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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1answer
86 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 ...
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1answer
708 views

Measuring noise with an oscilloscope

What is the proper procedure to measure RMS noise with an oscilloscope? I have 2 standard resistors, 1k and 100k and a 1.5GHz BW, 5GSa/s Keysight DSO. I have a probe which offers 1:1 (1MOhm//100pF) ...
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1answer
85 views

What's the difference between measurement resolution and digits per second in time measurement devices

In time/frequency counters/analyzers in technical specifications you can almost always find resolution and digits per second values next to each other. What is the difference?
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1answer
76 views

How to measure weight at end of arm

I have a setup where I need to measure the weight at the end of an arm. The arm is clamped between two pieces of aluminum at one end. The Sensor S is mounted a short distance (5cm?) from the aluminum ...
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1answer
187 views

ADC MCP3421 sample rate problem

I am writing a driver for mcp3421 ADC IC and I have a problem when I measure in 12-bit accuracy. That is 240 samples per second. In the datasheet the min and max values are 176 SPS and 328 SPS. So I ...
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2answers
303 views

Ac voltage measurement

Hi! I got a simple problem. My objective is to measure voltage and power factor of a 16V AC through a differential ADC (ADS1115) that measures voltage difference between 2 channels. I only managed ...
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1answer
106 views

How to measure Oscilloscope's self random jitter

I want to measure how much noise is a certain oscilloscope responsible for. Up until now we (my team) have used the approach of inserting a square wave and measuring the random jitter RMS. This method ...
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1answer
41 views

Measuring electro-hydraulic drive's inertia

I have an electro-hydraulic drive – a hydraulic motor with coupled to it a synchronous generator. Also there is an encoder installed on the shaft of the generator. By using my DAQ unit I will measure ...
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3answers
1k views

How to measure RMS value of voltage using CRO?

I want to measure the RMS value of voltage of half wave and full wave rectified sinusoidal wave using CRO itself. How do I go about it?
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1answer
113 views

Calculation of active power and apparent power through sampling

I'm currently working on a power meter device based on simultaneous sampling of current and voltage values, I intend to use this system to measure the active, reactive and apparent power on a non-...
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2answers
102 views

How can I reduce an oscilloscope's bandwidth to that of an Arduino's ADC?

The typical sample rate of the Arduino Uno's ADC is ~10KSa/s. Yes it can be overclocked, but lets just consider the normal situation. I'd like to 'simulate' the levels of a white noise signal that ...
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1answer
140 views

Improved Differential Amplifier

I made this circuit as shown below: simulate this circuit – Schematic created using CircuitLab After those improvements with current mirror and constant current source were considered, this is ...