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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Matching network for two-port with internally matched inputs/outputs
Background
I had a lab in school where we were given an LNA with inputs/outputs matched to 50Ω, that will be connected to a 50Ω system:
The task was to design the input and output matching networks:
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How can I describe the loading effect of an ohmmeter?
How can I describe the loading effect in an ohmmeter? I've been given an assignment with this question, and I tried to look it up on the internet but could find no other material apart from loading ...
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Tension load cell options
I'm designing something similar to an electronic hanging scale (think a heavy object on the bottom, with a scale attached immediately above it). I am not that familiar with what the most typical way ...
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Test lab noise floor variance and emission limits
I have recently taken part of noise floor measurements for emission tests from two separate EMC labs, both well known and international companies. The thing that shocked me is the dramatic difference ...
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Contactless measurement of internal time base
I'm currently trying to measure the internal time base of stopwatch (both mechanical and digital) to ascertain the expected accuracy of the device. I have looked through many articles related to the ...
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How do I calculate the minimum deflection I can sense with a strain gauge, like the BF350-3AA?
I have a strain gauge (the BF350-3AA), and I will be connecting it to an HX711-based amplifier sensor.
From its low-quality datasheet, I've pulled out the following figures:
Nominal Resistance: 350 ...
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How can I correlate a RSSI value to a distance measurement more efficiently?
I want to develop a trilateration algorithm using 3 fixed advertising beacons in different parts of a room and a mobile receiver which continuously gets the RSSI values of the 3 fixed beacons and ...
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HLW8032 energy meter circuit showing power usage at no load
I am designing an AC energy metering circuit. The circuit has to measure voltage, current, power, power factor and energy used for two channels (from the same source). The HLW8032 transmits 24 bytes ...
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Can I use 12 V and -12 V together?
I am sorry if this question is pretty easy but I am a beginner.
I have a PC PSU that provides two lines:
12 V 11A
-12 V 1.5A
If I used them together will I get 24V, and how many amps can they provide?...
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Measuring flyback SMPS feedback loop response
I'm trying to measure the feedback loop on a isolated flyback SMPS. My goal is to determine the phase margin and 0 dB cross-over frequency.
The most common circuit I have seen is the one recommended ...
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AC leakage issue with high impedance measurement setup
I am having an AC leakage current problem with my measurement setup that I typically use for lock-in measurements.
I employ a 100 M\$\Omega\$ resistor as a voltage-current converter, and in series, a ...
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Measure power & energy usage in tapped line
Here is the schematic of the circuit in question:
The horizontal lines are from the AC mains. Ammeters and wattmeters are connected at any 2 points in the main lines. I am trying to detect if the ...
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Measurement of relay characteristics so can detect before failure
I am working with a very large safety system which was designed around 30 years ago. It has a system of relays interlocked together in a logic configuration so that it will failsafe if any relay ...
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Debugging PLL STW81200TR not locking
I need a bit of debugging help with SWT81200 PLL that I am using on my custom designed PCB. I am able to configure registers through SPI communication, but the problem is that I am not able to achieve ...
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Criteria to see if a battery was over-discharged in the case of Li-ion cells and NiMH batteries
Consider a Li-ion pouch battery from an RC model. Is there any reliable way to determine by measurement if the battery was in a over-discharged state in the past. (In particular I am looking for ...
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Connecting LVDS to oscilloscope using ferrite bead to isolate GND/SHIELD
I want to measure LVDS signals with a scope.
Will my solution work? (Shown at bottom.)
I know of other ways of doing this, but I am hoping this way is cleaner and easier.
Specs:
Frequency:~100MHz
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S11108 Circuit Design Logic
This is my first post and also my first dip into electrical engineering, and I wanted to ask if you have any suggestions on the circuit I have designed. As a background, I'm a Computer Science student,...
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Using a DAC to measure system gain
I am using a Wheatstone load gauge through an AD8295 op-amp to a SAMD21 uC ADC. The op-amp uses a resistor to set gain. An analog switch is used to change gain. Since the resistors are not exact (G = ...
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How to eliminate internal circuit current consumption from the measurement in bi-directional current measurement circuit?
I am comparatively new in this domain. I am trying to design a bi-directional current measurement circuit. This is a 5V to 9V DC system. I have two USB C female ports at both ends. Which means I can ...
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Can I measure pinholes in a dielectric layer using LCR meter?
I have a thin dielectric film (~1 um) and I want to measure the quality of the film in terms of not allowing leakage current through pinholes. Can I use an LCR meter for this purpose? If yes, how? If ...
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How do you characterize the noise in a fluid velocity measurement device?
I have designed and built a measurement device that detects the velocity of a fluid flow (a constant-temperature anemometer). I wanted to experimentally characterize the noise performance of the ...
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Optical distance measurement idea [closed]
Ok, so I posted this using my phone some time ago, more than a year ago. However let's just take it from the top, integrating the criticisms that I remember.
I am a cnc machinist by trade and we ...
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Questions about connecting ADS1115 for voltage measurement
Purpose: to measure the voltage on the DC bus (about 600VDC).
ADS1115 Datasheet
I looked at the use cases and saw two connection options (in the first case, we use two inputs, in the second, only one)....
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Sigma-delta modulator (ADC), can it be used without sinc3 filter?
Purpose: isolated measurement of DC voltage (about 600V).
For these purposes, I found two options:
ADS1115 (I2C ADC) + I2C digital isolator
CA-IS1204 Isolated Sigma-Delta modulator
I am considering ...
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74LS283 4-Bit Adder doesn't work as I expected. It sets some inputs to high voltage
I bought a few cheap 74LS283 chips. They don't work as I expected.
For some reason it sets the A1 pin to high voltage (5V) at all times. Considering the A1 and B1 pins are supposed to be input pins, ...
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Generating Double pulse using Tektronics Function generator AFG31000
I have Tektronics AFG 31000 function genertor with built in double pulse test app. I want to generate two pulses for my double pulse test but this so simple task is becoming a mountain to climb for me....
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Why can't capacitors on PCBs be measured with a multimeter?
While looking at this article, it mentioned that one cannot test the capacitance of a capacitor while it is on a PCB. The explanation given is:
The reason is, that when a capacitor is inside the ...
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Current measurement in every 20ms
I want to measure the current in every 20 ms and record the measurement. I was using the Fluke DMM and in that I am not able to measure something less than 125 ms. Could someone suggest any methods ...
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A question about scope's channel affecting other
I have the Digilent's USB scope and when I couple different signals to Ch1 And CH2, the channels affect each other. I didn't observe this with another USB scope.
If both are coupled I get the ...
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measuring frequency with opto-isolator
I have a circuit where 220VAC mains is stepped down by transformer to 48V and through an 5k1 resistor I'm activating optocoupler that drives a LED through a resistor on the other side. I am measuring ...
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Is a semi anechoic chamber with absorbers on the floor a fully anechoic chamber?
I have a question about radiation measurements according to EN 300 328. According to the ETSI EN 300 328 V2.2.2 (2019-07) standard, measurements can be performed at one of the following three test ...
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Power transmitted from Arbitrary Waveform Generator
I have an arbitrary waveform generator. The arbitrary waveform has 2x CW tones of same amplitude. I'm only able to configure the overall power of this waveform, and the generator's manual says this ...
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How much of installed solar power is usable on average?
1 GW is the equivalent of 8.76 TWh in a year. When you say that you installed 1 GW of solar capacity do expect that it will generate 8.76 TWh in a year? On average, how much would 1 GW of solar ...
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Current drop with capacitor
I'm new to electronics, and there's something I can't figure out.
Can someone explain to me why, when I add C1, the current drops drastically in R3?
I was thinking that the impedance will be the same ...
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At what point along the active region should hFE be measured?
I know that hFE is not a particularly informative or reliable piece of BJT data and consequently the best designers create designs which function well without much regard to it but...
Out of interest, ...
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Error in current measurement
I am measuring the error ratio and phase displacement in a CT. The experimental circuit is the next.
The results with the oscilloscope show that the error ratio is not within the limits of the class ...
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How do I read a load cell just with this data?
I have a load cell (capability = 23 kg or 50 lb.) Its output is 2 mV/V. I have read that that means 2 mV per each excitation volt.
The power connection of this load cell is +15V-GND, so 0.002 * 15 = ...
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Standards for measuring analog audio signal devices
I'm making a Analog Channel Strip for a project. I'm searching for standards that let me or give me an advice of how to measure Dynamic Range, THD and THD+N, SNR, Frequency Response and input/output ...
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Frequency analyzer for loop gain measurement - Why should the injection point have low output impedance and high input impedance?
@5:08 The video mentions:
"The insertion point should have a low output impedance and high input impedance"
What is the background for this condition?
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How to achieve coherent sampling in practice
In the context of measuring a sinusoidal source with an ADC, coherent sampling (i.e. capturing an integer number of periods) allows the use of a rectangular window without spectral leakage.
How does ...
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Crystal detector power measurement and SWR measurement - How are they related?
I'm researching the application and behavior of crystal detectors, like the HP 423B. I understand the core principle of a detector: extraction of the 'video' signal that is amplitude modulated on top ...
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Is it necessary to implement a sensing resistor plus pre-amp with Faraday cage on a PCB if I would like to have the range about 10nA measurement?
I put a 60 kΩ sensing resistor plus low-bias current amplifier with a gain of 500 into an aluminium bag and tied it to AGND for EMI shielding. The second stage is an ADS1256 24-bit ADC. The purpose is ...
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Measuring output impedance of Widlar current source
I have designed the circuit shown below for a reference current of approximately 1mA and an output current of approximately 100uA. I have observed that I am able to supply approximately 100uA to load ...
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DC voltage 48 - 58 V to 0 - 10 V scaling
I have four 12 V lead-acid batteries in series and want to measure the total voltage. I'm interested in the 48 to 58 V range. How can I convert the range to represent it with a 0 - 10 V volt meter?
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Making earth pit in swampy area
I recently made an earth pit in a swampy area. I dug the earth up to 5 feet as water was available at 4 feet depth. I poured charcoal and salt in the ratio of 3:1 . After braising the copper plate ...
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Grounding issue causing problem with capacitive soil measurement
I am using a MonkMakes board to measure the wetness of some soil in a pot. This board measures the capacitance of the soil, converts this into a wetness percentage, and sends this value to the ...
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Keysight bandwidth and rise time
According to the following application note from Keysight, one way to know what device to take for measuring a signal is to measure the rise time. Then according to the rise time of the system under ...
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Getting Energy values from the Allegro ACS37800
I am currently using the Allegro ACS37800 IC to monitor power, from what I found on the datasheets and from the internet this IC is capable of calculating the voltage, current, and power. I actually ...
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Differential capacitance change measurement (sensing) with 74LS628
I'm researching the possibilities to accurately register the capacitance changes of a big metal plate (area 10 m2) to the ground (GND, yes - earth, soil). It varies around 100-200 pF.
For now I'm ...
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Need help with validation of the design of a capacitance sensor array for soil moisture measurement
Product Description
The device is a soil moisture sensing and analysis device that uses capacitance sensing technology to help manage soil moisture in your garden. One probe set at the bottom of the ...
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