Act of measuring voltage

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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
63 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
124 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
99 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 wire wire is for. As its top range is ...
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2answers
42 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
121 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
87 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
161 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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87 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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224 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
64 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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1answer
42 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
71 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
117 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
118 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
94 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
67 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
111 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
86 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
59 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
130 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
302 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
129 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
258 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
124 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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252 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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54 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
91 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 ...
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2answers
276 views

Why does a multimeter put more voltage to measure a smaller resistance?

I noticed this behaviour on two different multimeters (different models and brands as well). At first I did not put a multimeter in the way to measure how much voltage changed for the different scales ...
3
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2answers
259 views

Voltage divider to sense voltage on arduino

I am working on a DC voltmeter for monitoring my solar panels. Total voltage of my panels can go up to a maximum of 50 volts. I designed a voltage divider with 100k and 10k resistors. For full voltage ...
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3answers
313 views

DC step-up regulator wiring

I'm using a pololu step-up voltage regulator (http://www.pololu.com/catalog/product/2117) to go from an unregulated battery (VIN line from an Arduino, powered by a 3.7v LiPo cell) to 12V. No matter ...
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1answer
454 views

how to monitor the voltage level and protect the 3 phase induction motor against high/low voltage fault? [closed]

how to monitor the voltages of all 3 phase in 415v 3 phase system. i like to monitor the voltage whenever it is greater than 436v and whenever voltage gets lower than 394v. if the voltage exceeds or ...
0
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1answer
198 views

Can I use Arduino to alert by sound or LED when it detects a certain voltage

Can I use a Arduino board to alert me when voltage reaches 2.4v to 2.5v DC? Can I use a Arduino board to alert me when voltage reaches 0.7 mV sine or co-sine Ac? Or will I need sensors?
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1answer
114 views

Can current still be (alternatively) measured with a blown multimeter fuse?

With a blown fuse in a multimeter, is it still possible to measure current of a device by somehow measuring voltage and resistance? If so, how would this work? Do specific probing/measuring points ...
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1answer
168 views

Depletion region's length in diode

Assume that the \$C-V\$ curve of a Silicon diode is the following The equivlant \$\dfrac{1}{C^2}=f(V)\$ is shown next The slope will give me \$slope=\dfrac{2}{\epsilon q N_d}\Rightarrow ...
9
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1answer
818 views

Arduino: Measure external voltage

I have a "problem" while trying to measure the external voltage from a coin cell. I have simplified my circuit, but basically I have a DS1307 real time clock powered by the Arduino 5v output, and a ...
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2answers
288 views

subtract two AC voltages with instrumentation amps

I'm implementing the so-called "3 omega technique", where a thin metal line is excited with a sine current. The metal has a high TCR which causes a 3rd harmonic oscillation, and I need to measure the ...
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0answers
79 views

adjustable battery indicator

I've got a simple circuit powered by one 18650 LIon battery. Now i want to light up a LED when the battery voltage drops under a specified value (e.g. 3,4V) I know it would be easy with a ...
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3answers
188 views

Measure current on a constant current source

I need to measure current on a constant current source(LM317), because I am using a 3v3 chip I also need a voltage divider to read it. Will this circuit work Or will it wreak havoc trying to increase ...
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2answers
1k views

ADC for measuring 0-5V but connected to 3.3V device

I have a BeagleBone (BB) and want to connect the analog output of a motor controller to it. The motor controller creates an output in the range of -4V to +4V and the BB anlog inputs only accept ...
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3answers
322 views

How do I calculate the input voltage based on an ADC reading?

+UB is a 12V power supply. I have to find the voltage on U_KL30. I take this U_KL30 as an input at PortA<1> of my MC9S08DZ60 and use an ADC to get a ...
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5answers
370 views

Flow of current in a simple inverting amplifier circuit

I am considering a simple circuit like the one below. Let us say that the voltage source suddenly turns on (from 0V to 1V), then current will through through the resistor R1, correct? But assuming ...
2
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1answer
334 views

Why does my PSU die everytime I test with multimeter

I've set up my PSU to use as a "lab power supply", I'm trying to obtain 12 Volts at 14 amps. I have the red, orange, yellow, black wires separated, and connected the green wire to ground to keep the ...
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1answer
139 views

Battery Monitoring IC for 24V 480Ahr SLA

I'm building a battery monitoring system for a large automotive application. Is there any IC tuned to measure a Lead-Acid battery pack's voltage, current and state of charge? The closest I got was ...
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1answer
118 views

Why do my 3 custom voltage pulses stop working as soon as I plug in the A1362 Hall-Effect sensor?

Why does the Vout pin in the diagram below receive 8 volts with Vcc = 0 volts, but becomes 2 volts when Vcc=5 volts. If switch SW9 is closed, circuit theory says Vout should always stay at 15 volts ...
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106 views

Embedded system-current draw logging

I have an embedded application that wakes up every 15 minutes and performs some specific function for a period of two minutes. I need to log the current consumption of this specific function on the ...
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0answers
134 views

Need help with generating a bi-phasic current

I'm trying to generate a symmetric biphasic current pulse using a Grass S88 Stimulator. Here's a diagram: SG is a signal generator with two outputs, S1 and S2, which are generating a periodic ...
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2answers
486 views

Measuring external voltage on Arduino

I have a Logitech Steering wheel which I would like to interface to an Arduino whilst using it on a Playstation. My aim in the have the inputs from the gas and brake pedals light up a bar graph to ...
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1answer
353 views

Lipo battery monitor for 1s-6s packs

I want to be able to output lipo battery voltage to a display the remaining juice in the battery much like a fuel gauge. It has to work for 1s to 6s batteries and it would be ideal to work using an ...
2
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1answer
2k views

Measure 12V 35Ah battery level in arduino

I am building an arduino device controlling a solar power system. I am a beginner and would like to know what kind of part I would need to connect to the board to acheive this.