Act of measuring voltage

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71 views

Why is voltage 0 after the last component in a circuit given electron current flows from negative to positive?

Perhaps a different way to ask my question is why does voltage drop occur on the negative side of a component and not the positive given what is known about electron current? E.g. in the diagram below ...
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1answer
34 views

dual ramp voltmeter meaningfully displaying the microvolt digit

How can a common dual ramp voltmeter meaningfully display the microvolt digit when measuring a DC voltage ridden by a 50 Hz signal of several millivolts captured from the power distribution network.
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3answers
107 views

Wheatstone bridge why not use a voltmeter?

I have been reading up on the limitations of a Wheatstone bridge, one of which is that for high bridge resistances any imbalances are hard to detect because of the small current that flows through the ...
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2answers
123 views

Bench DC power supply output

I recently purchased a ATTEN APS3005D Regulated DC power supply from eBay and I'm having some odd and potentially alarming results that I'm trying to get my head around. Note: I'm testing this ...
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1answer
60 views

Provide power if power is not present already (circuit inside)

I am designing a simple controller for an automotive application. As you can in the schematic below, they system is consisted of a sensor, a gauge and a controller. This particular sensor shorts its ...
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1answer
37 views

How to read a wider range of voltages into the SA ADC on a PSoC4?

I want to read in a larger range of voltages into the SA ADC on the PSoC4, however as stated on the data sheet for the ADC component the different modes can only allow a range of 0 to 2 - 3 V and I ...
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1answer
122 views

How does a smart phone measure the battery power?

A smartphone (assume Android) usually displays the battery percentage from 0 to 100%. I am assuming this is the usable power capacity of the battery. I have several questions: 1) How exactly does it ...
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1answer
59 views

Measuring the charge of a battery while charging

Determining whether a 12V car battery needs charge is as easy as touching its leads to those of a multimeter. While charging from a vehicle's alternator, the multimeter method fails to determine the ...
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2answers
132 views

1000 watts, 220 volt, 52" length, Coiled Nichrome wire

I need to use Nichrome wire for heating purposes. My heating temperature could be among 200 Celsius, voltage should be 220V, wattage should be approximately 1000 Watts, and length should be 52 inches ...
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10answers
2k views

Why can a voltmeter still measure potential difference if it has a (theoretically) infinite resistance?

I am a physics teacher who did engineering and hated all things electrical! Hence when my students sometimes ask me how a voltmeter can measure the potential difference between two points if there is ...
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2answers
69 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
52 views

pin connection added

I am trying to communicate 24 hall sensor via arduino & 8:1 Mux . I am using CD74HCt4051E 8:1 multiplexer. Instead of hall sensor i have used potentiometer 24 nos and connected to MUX IC devide ...
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1answer
43 views

Resolution Digital Voltmeter

If I have a 3 and half digital voltmeter operating on the voltage range of 40V then what would be its resolution? While trying to solve this I found in one of the books that only active digits ( which ...
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2answers
85 views

Series RLC measurement result different with theory

I am measuring the current and voltage in simple RLC circuit: However,the result that I measured show big difference with the simulation result using Multisim. Why is there are a big difference ...
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1answer
335 views

What causes inaccuracy over time on a DMM?

Here is a piece of information from a datasheet of a DMM. The accuracy rates seemed interesting for me. I wonder what causes difference in the accuracy, especially the changes after 24 hrs? Is it only ...
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2answers
72 views

Combining power [closed]

On a computer power supply can I add 12 volts and 5 volts supply to get 17 volt supply? **Edited for clarification
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1answer
73 views

Single Phase Energy Meter using Atmega32

Version 1 : We are trying to measure the input voltage from the AC mains (which theoretically should be 230 V). The circuit to measure this is a simple resistor divider network as shown below. The ...
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0answers
100 views

Voltage/current Monitoring - MAX4172 + ADC vs. INA219

I'd like to add some monitoring of voltage and current on the +5V and +3.3V supply rails of a development board power supply. I'm currently debating between two approaches. The first approach is to ...
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0answers
68 views

Node voltage analysis of PMOS charge pump

Why is it that the voltages at nodes A and B are 3.7 V and 7.4 V respectively at a certain phase, i.e phase 1? And just the ...
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1answer
78 views

Measure battery voltage

For a LiPoly-accu driven device using the Olimexino-32u4 board (includes LiPoly charger) I want to measure the accu state (voltage?). How to measure the voltage without the need for a current ...
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4answers
115 views

MiniQuadcopter ESC connection

I have a picture here, sorry if it's ugly .. but let's think, they are my ESCs for my mini-quadcopter. My mini quadcopter is 3d printed, and as much as possible, I don't want to use bullet connectors ...
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3answers
2k views

Why does an oscilloscope show a different voltage from a signal generator?`

I have a Rigol DS1052E oscilloscope and a Rigol DG1022 function generator. I have just changed the oscilloscope fan for a silent one, as I found, as is commonly reported, that the original fan noise ...
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1answer
62 views

Modifying a chip on a bought voltage measurer

I have bought a battery checker for my RC LiPo battery packs. The battery checker can measure and alarm at low voltages between 2.7 and 3.8 volts, however with LiPo batteries, the interesting range is ...
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2answers
1k views

RMS vs DC(mean value) when calculating power of pulsed or rectified signals

When I have either a rectified signal (like the unfiltered rectified sine wave out of a diode bridge) or say a fast pulsed signal feeding a LED and resistor, in which both the DC component and the RMS ...
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1answer
84 views

Frequency modulated voltage measurement with VFC voltage to frequency converter and counter

I would like to measure the voltage across a nonlinear high voltage pulsed power circuit. The pulse is an underdamped RLC discharge but with some non linearity in the inductance. A quarter cycle is ...
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2answers
332 views

How to measure microvolts of biopotential with Arduino?

I'm new to electronics, so don't judge me harshly. I need to measure the biopotential of a human. I will place special electrodes on the skin, and need to measure the voltage on it. Ordinarily, the ...
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2answers
55 views

How do I measure time delay from power ON to console messages

I am working on Microzed board (schematic is here). User guide is here I want to measure time elapsed right from Power ON to first message that comes on the console. The message on cosole comes ...
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1answer
117 views

Backward measurement of AVcc against reference voltage connected to ADC input

what you think about ADC backward measuring supply voltage in microcontroller? It looks interesting for battery-powered devices. The idea is: Connect constant voltage (some voltage reference IC) to ...
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2answers
132 views

Broken phono pre-amp, is op-amp bad?

The left channel of a phono input on a mixer is outputting only noise. It is measuring -8V DC across input terminals, while the other channel is measuring 0V. The dual op-amp, a 4580, is getting ~27V ...
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2answers
70 views

What is the function of the voltage meter in this circuit?

simulate this circuit – Schematic created using CircuitLab See the above schematic. I don't know if it's 100% correct, because it's my first time using it and some of the symbols are ...
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1answer
198 views

Nodal analysis independent and dependent voltage source and current source

After spending quite a few hours I am stumped with this problem while trying to solve for Vo, which is supposed to 0.5V and this was confirmed through PSpice. I have no idea what I am doing wrong or ...
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1answer
82 views

What is the distortion introduced by a multiplexer?

Question in short: If I have a multiplexer, and my selected input is X volts, I suppose that the multiplexer's output will be X+-ΔX volts. How can I calculate ΔX ? Question with more details: I ...
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1answer
220 views

Circuit to provide 0-5 V output proportional to 0-30 A from C.T?

I want to design a circuit to protect oveload current of 30A.I have a controller board(PLC) which accepts the voltage range of 0-5 as an input and C.T with 1:7000 turns which can maesure 0.5 -60 ...
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2answers
210 views

Understanding crest factor of a voltmeter

I was studying signals and systems and came across the crest factor which is defined as the ratio of Vmax of the signal to the rms value of the voltage with the dc component removed. It then proceeds ...
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4answers
551 views

What is the white wire for on this voltmeter?

I found this voltmeter on eBay, and I know what the red and black wires are for (live and ground respectively, or alternative names), but I have no idea what the white wire is for. As its top range is ...
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2answers
53 views

Galvanic Voltage and Current strength

This is a mouthful! I have a copper pipe fixed with zink coated (galvanised) saddles. I want to ascertain what the voltage would be in the dissimilar metal galvanic reaction between zinc and copper? ...
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3answers
296 views

How do you set the reference voltage for a comparator?

I know this is certainly a beginner's question but am a first year student so hopefully I can be forgiven. I was looking through a electronics booklet provided by IKES website, and it's talking about ...
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2answers
298 views

Multi-cell battery measurement design

The task is to measure the voltage of individual cells in a 48-cell battery pack of AA cells in series. The measurements serve to log performance statistics, warn the user if/when a cell dies, or that ...
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1answer
707 views

What does the moving iron voltmeter measure in a circuit, average voltage or RMS voltage?

What does the moving iron voltmeter measure in a circuit, average voltage, \$V_{average}\$, or RMS voltage, \$V_{rms} \$? \$V_{average}=\frac{1}{T}{\int_{0}^{T}vdt} \$ ...
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2answers
115 views

At what resistance do I not see a voltage drop across a resistor?

If I have a circuit like this and measure the voltage drop across the resistor I get a value, regardless of what resistor I use: However, if I stick a piece of wood in there instead of the resistor ...
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3answers
419 views

Computer line-in voltmeter

I'm about to make a voltmeter from computer line-in. In some strange way I can not see direct current from computer. Why does it work only with alternating current? What information does captured wave ...
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2answers
155 views

Can I use LIPO battery voltage checker for 12V lead acid battery? [closed]

Can I use the LIPO battery voltage checker to monitor voltage of my 12V 7Ah lead acid sealed battery? Currently I use a multimeter to check the battery voltage frequently as I am experimenting with ...
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2answers
78 views

Switching setpoints of a low voltage monitor

I'd like to build a low-voltage monitor that is adjustable by flipping a switch to one of two setpoints. There are plenty of sample circuits, below is one adapted from here I'd adjust the R2 and R3 ...
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1answer
132 views

Simple doubt regarding Half-Wave Rectifier voltmeter

In the book first this form of half-wave rectifier voltmeter is introduced and then the author says that there is a problem in this circuit that when the ac source is in the reverse direction there ...
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2answers
198 views

Use microcontroller to measure the microcontrollers voltage

When using an Analog to Digital Converter (ADC) I want to convert to millivolts (mV) afterwards. My microcontroller is running on 3.3V, but I want to measure more accurately to get better result. ...
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2answers
386 views

Convert 10.5V to 15V into 0 - 3.3V range for adc input

I need to measure a voltage range of 10.5-15V to 0.025mv accuracy. This is a resolution of 180,000 - which is huge i know. The reason for this is because I will be measuring the voltage drop across a ...
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1answer
869 views

Measure voltage and amperage drawn by an Arduino?

so I'm in a green engineering class in high school, and my friend and I have been tasked with a special project, measuring the amount of power drawn by an arduino so that we can determine the energy ...
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1answer
571 views

burden resistor and/or voltage divider in an energy-sensing CT setup

I want to (eventually) build myself a home power monitor using basic current transformers. While reading on various circuit designs, I've stumbled upon what must be a very basic question. If we look ...
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3answers
205 views

Reducing power supply ripple for GSM modem

I'm powering a SM5100B GSM modem from a 5A bench supply (peak current is 2A). The required supply range is Vmin=3.3V, Vnom=3.6V, Vmax=4.2V, so I'm giving it 4V. Every so often, the module will reboot ...
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1answer
158 views

How to use an ADC with a non zero lower reference voltage input

I need to convert, linearly, a voltage in the range of about 1v to 2v into the range 0 to 1v for input to an ADC. This is the background: I fiddle with electronics and programming as a hobby to give ...