Act of measuring voltage

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52 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
41 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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0answers
49 views

Arduino: read voltage from circuit and prevent current flowing into add-on circuit

I have one of this led projectors which comes with a PIR motion detection sensor attached to it. I want to be notified when motion is detected and the projector is turned on. I have taken it apart ...
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1answer
23 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
76 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
324 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
46 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
63 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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61 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
68 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
105 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
1k 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
55 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
786 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
75 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
252 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
51 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
110 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
117 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
66 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
172 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
78 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
173 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
189 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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3answers
322 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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49 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
251 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
250 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
507 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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107 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
350 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
137 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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74 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
113 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
175 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
319 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
704 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
387 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
191 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
145 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 ...
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1answer
69 views

Determining Nodal Voltages

I have the following circuit, and have asked to be found the potential Vo: simulate this circuit – Schematic created using CircuitLab Using nodal analysis and Kirchoff's Current Law, we ...
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3answers
264 views

Nodal analysis with two voltage sources

EDIT: I am not removing the linked question and redoing the question. How do you formulate an equation on a node with two voltage sources connected in it, regardless if it is a supernode or not? ...
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2answers
576 views

Three phase rms voltage calculation

I am new in instrumentation and control. I am developing a hardware for a project and the following is my application. I have three phase stepped down voltages and stepped down currents entering my ...
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2answers
194 views

How to measure current with multimeter

I want to measure both voltage and current from an output expansion port, of the BeagleBoard-xM. I managed to measure voltage by putting measuring lead (red) to the expansion port and reference lead ...
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4answers
554 views

Connecting ADC pin to op. amp. output distorts signal

I am using a STM32 Cortex M3 microcontroller and have configured the ADC. I have verified that the ADC works by measuring different voltages on the micro controller eval. board. When I connect my ADC ...
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1answer
161 views

Battery measurement after charge

I got a Ni-Cd battery (8 AA) 9.6 V, 700mAh. After a 2 hours charge by an AC/DC adaptor (9.6 V, 250 mA) I take the following measurements by the multimeter: Voltage: 11.28 V (DC) Current: almost 10 A ...
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713 views

Converting variable capacitance value to variable DC voltage level

I need a simple method to convert a small variable capacitance value into considerable variable DC voltage. Capacitance value range = 0nF ~ 14nF DC value range needed = 0V ~ 6V What I've tried ...
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82 views

AD536 rms reader maximum voltage?

I want to use AD536 as rms reader. I have no experience on this specific device. According to its datasheet ( page 1 line 21) it is well protected against input over-voltage. In fact, what was ...
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2answers
110 views

Measure signals without connecting the grounds.

I have a board(BoardA) with a MCU which are powered from a battery. the board also has a buffer circuit for the ADC. I would like to measure a signal from an other board(BoardB) which is powered ...