Act of measuring voltage

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4
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2answers
303 views

ATTINY85 measuring internal voltage

I'm using an ATTINY85 for a portable application that uses a Lithium-ion battery; therefor I need to monitor the battery voltage so I don't kill the battery. Is there a way to go about this without ...
0
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4answers
66 views

LED Voltage Drop Confusion

Please take a moment to checkout the simple circuit below: simulate this circuit – Schematic created using CircuitLab As you can see, this is a simple circuit consisting of three LEDs in ...
1
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2answers
73 views

Measuring voltage between two points…wirelessly?

I want to measure voltage between points A and B. Let's assume that there's some obstruction/difficulty in simply attaching cables between those points. Is it possible to measure the voltage ...
0
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2answers
48 views

Low voltage cutoff circuit

I'm powering an attiny45 from a lithium ion battery; using these batteries the voltage cannot get below 3volts or it will damage the cell. How should I go about cutting the voltage out? Software, or ...
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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 ...
0
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5answers
77 views

Why does ammeter or voltmeter measures RMS value

When there's an alternative voltage, why does the voltmeter measures rms value instead of the value at that specific time?
0
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1answer
77 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 ...
0
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1answer
38 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
132 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
171 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
76 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 ...
0
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1answer
51 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
158 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 ...
0
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1answer
66 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 ...
0
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2answers
200 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 ...
21
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10answers
3k 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
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 ...
0
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0answers
56 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 ...
0
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1answer
52 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 ...
0
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2answers
94 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
337 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
91 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
118 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
70 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 ...
1
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1answer
81 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
123 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
3k 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 ...
0
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1answer
69 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 ...
-1
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1answer
94 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 ...
0
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2answers
373 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
57 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 ...
3
votes
1answer
119 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
143 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
71 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
240 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 ...
0
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1answer
84 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 ...
0
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1answer
253 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 ...
2
votes
2answers
218 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 ...
0
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4answers
679 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
54 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
333 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
330 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
886 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} \$ ...
0
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2answers
116 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 ...
3
votes
3answers
456 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
172 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
82 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 ...
2
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1answer
138 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 ...