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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48 views

Under water distance measurement

For a laboratory / field test, I'm looking for an easy solution to measure the soil surface elevation. The test runs a flow on a bed. When the erosion takes place the sediment concentration goes high ...
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1answer
50 views

Characterization of Power Harvester

I have chosen a power harvester to power a few things as part of a wireless system. This one is the one I have and it seems to be operational: http://www.powercastco.com/PDF/P2110-datasheet.pdf ...
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4answers
359 views

Is this true RMS?

This question is about obtaining a true RMS voltage reading from a running sampling ADC. Does this give me a true RMS reading, or where did I made a mistake? Construct a ring buffer of an large ...
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1answer
60 views

Measuring Output Amps From a Power Supply

I am in the quest to build a cheap bench power supply, i have successfully designed, built and tested the entire voltage circuitry. The device includes a graphic LCD screen that displays the voltage ...
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2answers
27 views

Technique to measure/infer Vf for LED given If

This isn't the normal resistor question, and I'm familiar with the theory and Which is better: using a resistor with an LED, or "precisely" matching the Vs to the given LED's Vf rating? ...
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1answer
56 views

How to measure the quality of a USB charging cable?

I have a set of USB cables (data and charge) and I noticed that, for a given charger, the charge time differs by cable. What would be a good way to measure the charging fitness of a USB cable? ...
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1answer
55 views

Abstract Datasheet Dimension Notation

I am attempting to create a footprint for a Surface Mount Component and I am using the manufacturer's datasheet for reference. They include PCB dimensions but the notation used is a bit confusing. It ...
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0answers
43 views

how work this flow meter

As you know , The principle of operation for the magnetic flow meter is based on the Faraday’s Law of Electromagnetic Induction.An electrical current (I) is applied to a coil package inside the flow ...
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0answers
26 views

How to calculate distance between two objects(robots)?

If I have two soccer robots, and want each robot knows the distance between itself and it's teammate, how can I do that? (without external supervisor camera)
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2answers
81 views

How to break out SMD chips in-circuit?

For a current project I am attempting to amplify and cross-wire the signals from the address pins of SMD RAM chips. Basically this means I am trying to break out the pins of a SMD chip, similar to how ...
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5answers
152 views

How measure the voltage over a large resistance?

I know initially this question might come across stupid and obvious but all is not as it seems. I want to measure the voltage drop over a 10M ohm resistor but my voltmeter's probes have an ...
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0answers
40 views

IR temperature Sensor reading ambient temperature in a room

I bought a product that has a IR temperature sensor and I want to receive a "good quality" ambient reading of a room. I have an idea how to use the IR sensor for the ambient, even though it would be ...
0
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3answers
120 views

How to measure nano-amps easily?

I want to measure the stand-by current of the PIC, but my DVM has minimum 2000micro (u) amper switch. It shows 0 micro amps when in 2000 u amps mode. Without building circuit a complex (more than 3-4 ...
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1answer
84 views

Anyone may suggest a temperature sensor technology that will work to a max of 200ºC?

Cheapest sensor technology as possible, up to +- 5ºC or 5% of accuracy. Better if it doesn't need complex (and costly) additional circuits.
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1answer
47 views

Uncertainity Calculation

> How can i calculate the absolute uncertainty dt in the following case T=(P/A)^1/4 if ...
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2answers
56 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 ...
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2answers
64 views

Full wave AC Voltmeter Vs True Rms Voltmeter

Does a full-wave rectification AC Voltmeter give the same indication as a true rms voltmeter when you measure a 50 Hz sine wave?what happens if the the sine wave is clipped by an inadequate ...
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1answer
99 views

Is using a transformer at reduced voltage a bad idea?

My Google is failing me. I want to make an isolated AC voltmeter capable of working at 120 or 240 VAC. I've found a suitable 240 volt to 5 volt transformer to use (current capacity doesn't matter - ...
3
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1answer
62 views

Power supply noise measurements

Im working on a project where I need characterise the noise from a power supply so I can then design some filters. The power supply provides 5V, 12V and -12V to a set of analogue sensors (hence the ...
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2answers
97 views

Oscilloscope measuring of PMT in photon counting mode

I have a setup as drawn below: DC source of 15V connected to high voltage (HV) source of 1500V connected to photomultiplier tube Hamamatsu, R1-R3 are resistors builtin the socket of PMT (there are ...
3
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1answer
122 views

How can one measure extremely low-uf capacitors?

I'd like to measure (to a few percent precision) the capacitance of a 0.8-0.06pf variable capacitor (eventually to be read by a 120mhz 32-bit microcontroller, if that's any help). I realize that one ...
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1answer
87 views

Measuring inductance and ESR of a motor using LCR meter

I am building a circuit, where a MCU will drive an unipolar stepper motor through MOSFETs and constant current source (not included in the schematic). simulate this circuit – Schematic ...
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1answer
74 views

Would adding an LED to a multimeter's LCD screen affect readings?

I purchased a TekPower TP4000ZC multimeter, which has no backlight for the LCD. I wish to add one myself, perhaps a single led at low current, driven directly off of the two AA batteries. I'll add a ...
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1answer
72 views

Long term voltage change - analog voltmeter, op-amps and logarithmic scale

I want to display one minute voltage change on analog voltmeter. Voltage change: from -0.5V/min to +0.5V/min. My analog voltmeter has 0-10V scale (I will replace it with homemade printed scale). ...
2
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1answer
159 views

Why is the capacitance changing while measuring?

I have 2 different 100nF capacitors. Let's call them A and B. My dad told me that B is "better" than A. I've tried measuring their capacitance using a Metex multimeter which has the option of ...
2
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1answer
89 views

Transformer frequency dependence

I have a transformer that I've taken out of scrap. I'm trying to discern it's electrical specifications. In my setup I have a function generator hooked up to the primary winding, and an oscilloscope ...
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1answer
54 views

Multimeter capacitance

I am using Multimeter Voltcraft M-4650B to measure the voltage in the test point of a high voltage circuit. I want to find out the stray capacitance of my cable and for that I need to find the ...
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2answers
96 views

TTL signal: output impedance, overshoot and other characteristics

I have an assignment for my Electronic Measurements and Instrumentation course, specifically me and my group were asked to perform time and voltage measurements using reflectometry on coaxial cables. ...
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1answer
78 views

Measuring components of current

When measuring input current to a primary winding of a transformer with an inline true RMS multimeter, can no-load current be measured, then full load current be measured, and then simply subtract ...
3
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3answers
267 views

What is the test voltage of a ohmmeter?

Ohmmeters don't appear to make LEDs conduct which gives overestimates in the resistance measured (tested with a R1//(R2+LED) parallel circuit). So what is the voltage they apply to the circuit, ...
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1answer
79 views

How to measure power/energy with analog circuit?

I would like to measure either power (running average, for example exponential average with a certain time constant) or energy (power integrated over time) with an analog circuit. The setup I have ...
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2answers
85 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 ...
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0answers
20 views

Sony Ex Data Acquisition Frontend

I am looking for information on a third party driver for the Sony EX-IF10 data acquisition frontend. I know sony made drivers for Matlab and Labview as it was advertised in promotional materials. ...
2
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2answers
198 views

Why not use audio codec chip as measurement ADC/DAC?

I am working on a project that needs simultaneous ADC/DAC. The specs of the on-board ADC in typical microcontrollers are pretty weak, and separate ADC with good specs are much more expensive than ...
6
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1answer
541 views

How to set the oscilloscope to measure potential between two points that aren't ground?

We have to measure the voltage across a-b in this circuit with an analog oscilloscope, but neither of these points are grounded. How should we put the channels of oscilloscope to perform the ...
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1answer
134 views

Why does the GND of the Arduino oscillating as well?

I have an Arduino Uno and what it does is simply output an oscillating signal of 1 MHz on PIN11. I measured the signal using a oscilloscope and a probe with a ground clip. First, I connected the probe ...
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0answers
46 views

How do you measure a distance along the Z axis in Altium?

If you hit CTRL+M, it's easy to take a measurement along the x or y axis. If you want to measure along the Z axis (for instance, the height of a 3D body), how do you do it? I googled "measure the ...
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1answer
121 views

resistance measurement problem with digital multimeter

I accidentally caused a short circuit with DMM common lead while measuring 220 AC voltage. then when I tried to measure resistance it gives me a reading of 3500 ohm while there is no resistor ...
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0answers
38 views

Implementing Peltier temperature controller in a circuit

I need to measure the temperatures of semiconductors using a Peltier temperature controller. I am using a DT9818 (it's a USB collection board from what I have learnt). I would need to use software ...
2
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3answers
166 views

How to identify if noise is coming from circuit or scope?

Occasionally, I'll be probing a circuit and would expect to see something specific and sometimes I see either crap or the signal im expecting with crap. This video from EEVBLOG is a good example of ...
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1answer
135 views

Can I increase inductance using permanent magnet ?

I know that when I insert a ferromagnetic core inside an air-cored coil, the inductance increases. What if I inserted a permanent magnet with a cylindrical shape into an air-cored coil, does the ...
3
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2answers
90 views

How to measure coils without Inductance measuring device?

I have a multimeter that can measures Capacitance, Resistors, voltage and current. If I have a known coil and unknown coil. Can I measure the ratio between the inductance of the two coils ? Is it ...
2
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2answers
105 views

Do LED and photodiode rise times matter for time-of-flight (TOF) measurement?

Do I need small rise times of an LED and a photodiode/APD when considering time-of-flight measurement? Given I know rise time of both diodes I am always able to count time of flight by subtracting ...
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2answers
98 views

Measuring internal resistance of a battery while it's being charged

I was startled to hear that there are devices out there that can measure the internal resistance of batteries, in circuit, while the batteries are being (trickle-)charged. For example, Hioki markets ...
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3answers
137 views

Very wide range high voltage measurement with optical isolation

I have a voltage source I'd like to measure, it is from 0V to 1kV, any value in that range. The accuracy isn't that important, but measuring with an accuracy with 1-5% would be perfect. This has to be ...
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2answers
110 views

How much power does a GPU actually use when only doing PCIe I/O, or only compute?

I hope this is the right sight to ask such a question, if not please be kind and direct me elsewhere. I have some discrete GPU with a TDP figure of X watts. Now, sometimes the GPU does Only ...
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2answers
300 views

How to measure current practically in a circuit

I have to measure this circuit, I have done the theoretical calculations using Kirchhoff's 2nd law, but I'm having troubles in measuring the current in each part of the circuit: I have to measure ...
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2answers
203 views

Measure LPG (LP Gas) level using an ultrasonic sensor. Which sensor?

I need to measure the liquid level of LPG through a thick 4000/8000/45000 stationary tank. They already have flowmeters but they are easily tampered. I need to be able to know how much Gas is in the ...
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0answers
60 views

Li-SoCl2 battery state of charge

I'm developing a data logger powered by Li-SoCl2 (http://www.100y.com.tw/pdf_file/02-SAFT-LS33600.pdf) battery and I have no idea on how to overcome the problem of estimating the residual charge of ...
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2answers
58 views

Measuring band-limited noise coming from an amplifier

I have a strain gauge amplifier and from my analysis, it will produce a low level of white noise above approximately 1kHz i.e. the power spectral density is flat above 1kHz. If I measure the output ...