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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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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How can I measure the power in mW of a radio signal?
I would like to build a small circuit to measure with my oscilloscope the power emitted by the 5.8GHz video transmitters mounted on my drones. On searching, I found this answer.
The question ...
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Translate voltage between line/neutral potential and ground potential (between primary and secondary side of PSU)
I would like to know how to translate a voltage difference between two independent reference potentials, as accurately as possible.
backstory:
We are building a active power measurement station for ...
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Precision current source and mΩ measurements
I'm trying to measure some resistors in the 3-5 mΩ range. I want to use a precision current source (picture below) and an AD7791 ADC for that purpose. I also want to use a 1.2 V reference voltage (...
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Why does the measured capacitance value of some ceramic capacitors keeps on increasing?
The capacitance of two ceramic capacitors were measured using an LCR meter (Agilent E4980A) at 1 kHz. The measured capacitance values of 100 pF and 100 nF capacitors are shown below.
The value of 100 ...
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Need to monitor a Li-ion battery using a 0-10 V output
I have an ebike with a weird proprietary BMS which is broken.
I want to replace it with a standard BMS, but there's a pin coming out of a connector on the battery that sends between 1 and 10 V to the ...
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Hysteresis measurement voltage behaviour
I am currently doing a hysteresis measurement using the below depicted measurement setup, however with different values.
The odd thing is that I have different VM2 values, depending on how I connect +...
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Low noise virtual ground, voltage reference or LDO + op amp?
I'm doing some sensitive signal measurements in 1~10kHz range where I amplify and filter (multiple active stages) a small voltage signal by hundreds ~ thousands of times and then sample it. A negative,...
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Source impedance influence on DC/DC converter input impedance measurement
simulate this circuit – Schematic created using CircuitLab
I have been tasked to verify the input impedance of a medium powered DC/DC converter (<1kW), and no experienced colleagues to ...
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Contact measurement
I have a mechanical assembly that is to be mated to another surface. To ensure that my assembly is correctly mounted before installation, I have a test piece I insert into it. When everything is OK ...
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Is it safe to briefly short the secondary of a power transformer to measure the maximum fault current at the primary?
I have a bunch of salvaged step-down mains power transformers (220V-240V primary voltage at 50Hz), with powers ranging from a few VA to maybe 100VA. In order to use them safely in my projects I need ...
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USB meter does not detect current in very basic USB circuit
I have a USB LED light (for plants) that draws 5 V @ 1.16 A when I plug it in, as measured by my USB volt/amp meter.
EDIT: The problem was caused by the specific USB tester model KWS-MX18L. See answer ...
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