Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [voltage-measurement]

Act of measuring voltage

Voltage is measured using a voltmeter. A microcontroller can also measure voltage using an integrated or external Analog to Digital Converter (ADC).

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Duracell PowerCheck - How Does It Work?

I've been using these batteries for a long time and I've never seen such a feature. There's a band on its outer wrapping having two ends: The white circle on the left side and the another one on the right side (not visible because it's under my…
Rohat Kılıç
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What is the voltage range of a standard headphone jack from a phone?

I want to connect the output from the audio jack of an iPhone to an Arduino. What voltage range can I expect to see on the audio lines from the iPhone? I assume that turning the volume up on the phone will produce a large AC voltage, but how large…
manuelBetancurt
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Why is the voltage measurement of this circuit different when the switch is on?

I built a simple circuit with two lamps and a slide switch powered by two 1.5 V batteries. When the slide switch is off, the voltage of the circuit measured by a multimeter is 3.15 V: However, when the slide switch is on, and the lamps are lit, the…
korppu73
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Multimeter exploded during ACV measurment - What did I do wrong?

simulate this circuit – Schematic created using CircuitLab A DT-830B meter. I bought a new transformer, and I was trying to measure the output voltage. I plugged the probes on 'VΩmA' (not 10 A) and COM. and set it to 750(not 100% sure if i put it…
user100933
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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 no current passing through the voltmeter. I can…
William Tabary-Peterssen
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Measure voltage with no current

Suppose I have a capacitor and I want to observe its charge decay over time. How can I do that without affecting its discharge rate through measurement? AFAIK a typical voltmeter runs current through a known resistance to determine voltage, but in…
feetwet
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Circuit for measuring high voltage DC voltage (up to 1000V)

I am a final year E&E student and I am trying to built a power meter that must be able to measure quite high DC voltages, up to 1000 V DC. I am measuring with a simple 12-bit ADC that has an input voltage range of 0 - 2.5 V. Would a simple voltage…
Eduan Shuda
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What value does ammeter or voltmeter measures (RMS, Average or Peak )?

What value does these meters measure? Is it RMS, Average or Peak value ?
Arun M
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Determine voltage drop over 10G resistors with cheap multimeter

I have two 10G resistors connected in series with a 3V battery. I want to determine the voltage drop across one of them, which of course is 1.5V. When I use my multimeter to check the voltage drop, it reads ~3mV, which I believe is because it has a…
John Smith
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Is it normal for DC wall adapter power supplies to provide voltages above the nominal ones?

When I measure a 9V DC wall adapter power supply with a multimeter it shows 11.8V. When connected to my board this voltage lowers to 10V. Is this normal? Should I be afraid of toasting my 1117CD-5.0 supplied board when using this adapter? Edit: This…
Jader Dias
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How does a smart phone measure battery percentage?

A smartphone (assume it to be an Android) usually displays the battery percentage from 0 to 100%. I am assuming that this is the usable capacity of the battery. I have several questions: How exactly does it measure the remaining capacity? Assuming…
navigator
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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 of the meter: I realized that by using my own…
Dakatine
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Why does battery voltage slowly return to the open voltage?

I'm doing some testing on a battery (MC002787). I've noticed that the voltage after a load takes a few minutes to go back to the open voltage (voltage without load for a long time). Can anyone explain why it takes so long for the voltage to…
Samuel Mathieu
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Monitoring voltage without a known reference

I'm working on a little sensor platform that runs off of batteries. I'd love to be able to trigger an alert when the voltage gets too low. The problem is that anything I use to measure that voltage will be powered by that same voltage source. For…
edebill
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High speed passive probe - contradiction between authors or different points of view?

In a document Hiscocks et al. describes some basics of Oscilloscope probe theory. The document is very understandable and seems coherent. Notice in particular that for him, the bad guy is the parallel capacitance of the coaxial cable and of the…
MikeTeX
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