# 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 ...
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/...
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 ...
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 ...
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 ...
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 ...
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 ...
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?
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 ...
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 ...
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 ...
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-...
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 ...
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 ...
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 "...
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 ...
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 ...
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: ...
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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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 ...
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: ...
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 ...
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 ...
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. ...
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 ...
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 ...
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 ...
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)....
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,...
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} \...
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 ...
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 ...
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 ...
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 ...
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 (...
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 ...
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 ...
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?
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 ...
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 ...
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 ...
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 ...
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 ...