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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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Digital bathroom scale circuit - how it works?

I'd like to understand how the digital bathroom scales work. I was able to gather that there are four three-wire load cells connected into the Wheatstone bridge as suggested below. The load cells have ...
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4answers
3k views

Big capacitors measurement(LCR meter related)

I digged up some capacitors from amplifier and decided to test them, one of them is said to be 8200 uF, the other 4700 uF. I measured them with LCR meter and it gives very strange numbers. If LCR ...
11
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3answers
857 views

Methods to measure inductance with high (1%) precision using standard equipment?

I am modeling the fine behavior of interacting oscillatory circuits. I have looked up a couple of methods for measuring inductance. I believe I am following the procedure faithfully, but the values I ...
4
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3answers
5k views

Measuring transistor beta (hFE) - Ib anomalies explanation needed

I've been struggling with details of building accurate (\$\pm1\%\$ tolerance maximum) beta meter. The simplest idea I came with went to a diagram as shown below, with R set to a value providing a \$0....
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4answers
1k views

Why do LCR meter manufacturers give the details of measurement frequency to us?

When you want to purchase a DMM, more probably you don't see at what frequency the DMM you considered would work, but in the situation you're considering to purchase an LCR meter, manufacturers give ...
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0answers
25 views

Can I use a RF and/or Time-domain reflectometer to find 'wet contact'?

Friends of mine have a circuit where the RCD trips but only after prolonged rain. There are a number of garden and security lights on that circuit so I very much suspect there is a junction box where ...
0
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2answers
101 views

How isolation is achieved in isolated channel oscilloscopes?

I tried to search something about this but found only a small amount of information. What confuses me is that all isolation amplifiers, optocouplers etc. I could find usually work at much lower ...
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0answers
70 views

Darlington Transistor TIP142 same type but different values

I have a bunch of Darlington NPN Transistors TIP142 that are removed from two separate identical boards. The 1st one have the TO−218 CASE (left side of the image) and the 2nd the TO−247 CASE (right ...
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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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0answers
52 views

Measuring current in the case of bridge amplifier at several MHz

Is there a way (or some chip) to measure current at about 5 MHz when the bridge amplifier is used? The output is a sine with amplitude 15 V. I need to measure accurately both amplitude and phase (the ...
0
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2answers
166 views

Biased single-source relaxation oscillator not starting

Vcc is 5 V , first op-amp LM358 provides 2.5 V ground for easiest possible relaxation oscillator build with MCP661 (2.5/5.5 V supply, 60 MHz operational range). I wanted to use it to measure values of ...
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4answers
836 views

Detect and measure fog outdoors

Currently working on a project requiring me to detect fog, and measure the amount of fog. It doesn't have to be accurate but it has to give a sense of how foggy it is. The device (probably Raspberry ...
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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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3answers
3k views

Why are null measuring methods considered to be very precise?

I heard a professor saying "it's a null method, so it is very precise". He was talking about the force balance pressure measuring method. I think in this cathegory of methods one can include the ...
1
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1answer
59 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) ...
0
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1answer
27 views

Measuring a magnetic pulse using a coil, and circuit adjustments

I have the following circuit, I am using it to create a pulsed magnetic field, in the coil. I am trying to measure and verify the magnetic field in the coil. I am testing it with 40 V to drive the ...
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2answers
67 views

Non-intrusive measurement of current and voltage

Sorry if this question is too basic for this forum... I'm an interested amateur but far from a professional. I'd really appreciate information from someone more informed than myself. Hypothetical ...
1
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2answers
70 views

Measuring Inductance

I have been looking the number of methods to measure inductance of a coil if you don't have an LCR meter available, and I have had some difficulty. I designed and built a coil and I would like to ...
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3answers
95 views

Which components can be measured while soldered on a PCB board already?

I am assembling nonlinear oscillators on PCB boards for applied math research [Colpitts (100 kHz, 3 V_pp), FitzHugh-Nagumo (100 kHz, 15 V_pp)]. I am working with some other people that want to do ODE ...
1
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1answer
59 views

Measurements using spectrum analyzer

I need to measure the following characteristics of a frequency synthesizer using a spectrum analyzer: Frequency range: 2.286 GHz to 2.346 GHz Output power: -2.5 dBm to 2.5 dBm SSB phase noise: ...
2
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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 ...
1
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1answer
36 views

Voltage Measurement with ST Microcontroller

I want to measure DC voltages from 1mV to 10V. I will be using STM32L053C8T6 Discovery board. I want to use 3.3V reference voltage. I know that if you want to measure voltages bigger than reference ...
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1answer
41 views

Measuring Frequency Synthesizer specifications

I need to measure all the electrical specifications of the Frequency Synthesizer KSN-2346A+ from Mini Circuits that appears in this datasheet: https://www.minicircuits.com/pdfs/KSN-2346A+.pdf but the ...
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1answer
33 views

Series/parallel combination of resistance/capacitance in an RC circuit (wrt LCR meter readings)

I have this equivalent circuit I am working on. I have to find out individual values of all components in it. I can measure resistance, capacitance and impedance of the whole circuit. I am not sure ...
0
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4answers
68 views

Oscilloscope coupling and effects on the measured signal

I have a basic understanding of the of coupling settings on an oscilloscope, but I need some help to understand what I am seeing on scope. I have a signal generator, with an arbitrary function set, a ...
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1answer
43 views

Problem in LC series resonance

I'm trying to experimentally verify my calculations on resonance on a simple series LC circuit. To prove resonance, I'm measuring the amplitude on the series resistor. When the amplitude is the ...
0
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2answers
51 views

Estimating torque of AC motor

Given voltage, measured current draw, and RPMs of an AC motor, and an estimated efficiency rating, is it possible to calculate the actual instantaneous output torque? Or is other information required? ...
0
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4answers
712 views

How does 3-wire RTD or resistance measurement works in bridge of wheatstone?

I cannot understand how 3-wire measurement will improve the resistance measurement. They say that IF lead resistance \$ R_L \$ is the same, it will compensate. How can this happen? If bridge is ...
3
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2answers
106 views

Oscilloscope: when to use coaxial instead of probes?

I understand the difference between passive and active probes, and between x1, x10, x100, ... I also understand that at high frequencies the capacitance of the oscilloscope has to be considered, so a ...
0
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1answer
46 views

RF measurement setup

I'm trying to take a simple measurement of ~2.4 GHz (WiFi land) with an RF spectrum analyzer (Tektronix RSA607A) but have so far been unsuccessful. On the RF In ...
0
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1answer
78 views

Measuring phase shift between current and voltage with microcontroller

I am trying to understand how this design is used to measure phase shift between current and voltage of an AC signal. From my understand there should be a PWM signal generated on the output. Resistors ...
0
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4answers
107 views

Multimeter, outlet and a Spark: the question of simple Voltage measurement

So I got a TekPower TP4000ZC MultiMeter. (Image source) It has COM port and two red ports: V-Ohm-etc. set at 600V Max and 500mA Max Fused 10A red fused port. Unlike other multimeters, there are no ...
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2answers
86 views

Measuring 0805 Capacitor values under 1nF

Other than investing in an expensive tweezer type meter for SMD components, what would be a good method for the layman to find the capacitance of an 0805 ceramic capacitor whose value is below 1nF? My ...
2
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1answer
70 views

Zero-crossing in AC with DC offset signal

Introduction I have a project about measuring the voltage, current and power factor of an electrical system. I had designed a system that allows the microcontroller to measure the peak of an AC with ...
0
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1answer
36 views

R&S Spectrum Analyzer Voltage Measurement Error

I just got FPC1000 spectrum analyzer that goes from 5 kHz to 1 GHz. I didn't had any spectrum analyzer experiences before this one so everything is very new to me. Among few things that I don't ...
0
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1answer
52 views

How to determine operating frequency range of an unknown 2-port device (with VNA)? [closed]

I have a question on hand: "You have an unknown 2-port device, the black box. Find the operating frequency range. Show how to do this with a VNA. Think of the settings, why?" VNAs can have a very ...
2
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1answer
84 views

How to measure a 100 ohm differential signal on a spectrum analyzer?

I have a pair of 1.5V PCML differential signals coming out of an Altera Cyclone V GX FPGA, terminated on the FPGA in 100 ohms with common mode voltage = 0.65V (also provided on the chip). I need to ...
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0answers
55 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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0answers
93 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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2answers
61 views

Modelling a temperature measurement system

The accuracy of a measurement system can be significantly reduced by loading effects in the system. A thermocouple is used together with an indicator to measure temperatures. The thermocouple has a ...
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0answers
32 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. ...
0
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0answers
32 views

Queries regarding multiple reflections

I have a measurement set-up as depicted in the figure below. The measurement settings are as following: Both Generator 1 were having carrier frequency 1 GHz and output power 0 dBm. No modulation as ...
0
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1answer
50 views

Is this current clamp meter measuring correct according to its specs?

A 24V DC power supply is supplying around 2.4A to a pure resistive load. The input voltage is 230Vrms. So I estimated the rms current drawn from the power network as: P/230 = (24*2.4)/230 = 250mA. ...
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1answer
221 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 ...
1
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1answer
50 views

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 ...
4
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2answers
3k views

Measuring accelerometer frequency with an oscilloscope

I've got a VTI CMA3000-D01 digital accelerometer and I'm controlling it via SPI from a Texas Instruments CC2540 chip using the embedded 8051 MCU. In the datasheet for the CMA3000, it mentions that ...
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1answer
593 views

Battery current measurement with shunt resistor

I want to use a shunt resistor to measure the current that flows from and in a battery. The current is set by power supply for charging(positive current) and by electronic load for discharging (...
0
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1answer
532 views

How does temperature compensation work for strain gauge in wheatstone bridge

Wheatstone bridge is used for temperature compensation for strain gauges If 2 strain gauges are connected like this figure. Due to temperature variation; the resistance Rg will change in the same way....
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1answer
70 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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1answer
66 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 ...