Questions tagged [voltage-measurement]

Act of measuring voltage

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Usage of peak-to-peak voltage and RMS voltage

Why are RMS values and peak-to-peak voltages common in use? For example RMS voltages in the context of noise. I see especially for peak-to-peak voltage no practical usage. Why should I need more ...
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Thermoelectric EMF problem for low voltage measurement load cell

The resolution of a load cell is highly dependent on its capacity. That's because the higher the resolution and the higher the capacity, the smaller the voltage change. For example, many companies ...
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How to measure change in TDS instead of absolute TDS through a TDS sensor?

I am using a total dissolved solids (TDS) sensor to measure TDS in an evolving solution system. The code below works fine to give the absolute TDS, but I would like to note the change in TDS over time....
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Do I need a precise voltage reference for my ADC if the what I am measuring shares the ADC voltage source?

I'm trying to design a basic measurement system using some phototransistors and ADCs to measure light absorption via a voltage drop. I've attached a schematic for a quick and dirty representation of ...
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1 answer
134 views

Cheapest way to detect low voltage of a battery

I have 29V battery which drops to 24V at about 30% capacity. I want to detect when the battery goes lower than 24V and generate a 12V signal. (I have 12V auxiliary supply for lights etc) Since I'm ...
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Is it possible for two MCUs to monitor the same analog voltage signal?

I was thinking about tying two separate microcontroller inputs together so that they would be on the same node and monitoring the same voltage signal. Both basically doing the same thing (analog to ...
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1 answer
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How to measure voltage with a floating supply?

In the example below, ground of a dual supply is referenced to +Vout. Assuming we have a MCU connected to VCC and +Vout, if we then try to measure the voltage at +Vout with the ADC, we're basically ...
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Current measurements for a DC motor being rectified when in reverse direction (differential low pass filter implementation)

Recently for a project I've been trying to capture voltage and current characteristics for a DC motor. To measure current, I'm using a single resistor (R1) in series with the motor, and feeding the ...
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Confusion of measuring the stator voltage of induction motor [closed]

I'm new to inverters and the only way I know how to measure the stator voltage of induction motor is to connect the multimeter to terminal of junction box. So could anybody please elaborate more about ...
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2 votes
5 answers
521 views

High precision resistance meter

I'm designing a high precision resistance meter, which will measure the change of resistance of a given remote resistor, which is not placed on the circuit PCB, against temperature. I want to do this ...
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4 answers
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AC volt meter using an Arduino not giving steady reading

I am trying to make an AC voltage reading system according to the circuit below which I found online. My voltage is coming out cyclical - why is that? Is the capacitor perhaps to blame for not ...
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How does a voltmeter determine voltage?

For example, using a battery. Does the meter place a small resistance in line with the two terminals, then measure current and solve for V using V=IR? I’m looking for the general theory.
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Arduino as a voltmeter

I need to read DC voltages between -2.5 V and 2.5 V with Arduino. I have read that an op-amp in inverting configuration (below) can be used to add a DC component. Therefore, I have thought about using ...
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1 vote
1 answer
52 views

Is it safe to connect an oscilloscope to a Power over Ethernet line?

I have found that PoE uses isolated power delivery. If I splice into my ethernet cable, will I be able to hook up a scope to one of the 8 lines inside safely without frying anything? The scope and the ...
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Using transformer secondaries for audio amp

I have a old transformer out of an audio amp and want to repurpose it for another DIY amp project using the LM3876. There is a 5 pin connector for the secondaries. I checked voltage potentials across ...
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1 answer
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Read in Arduino negative and positive voltages in a wider range

I need to read DC voltages on Arduino that can vary between -15V and 15V. As far as I know, Arduino can only read positive voltage values ​​between 0-5V. I thought of using a voltage divider with a ...
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2 votes
3 answers
97 views

How can I measure the output of a voltage booster circuit?

I made this circuit, which was described on-line as a "transformerless Joule Thief." I was able to light four LEDs of varying forward-voltage in series, but I couldn't figure out how to use ...
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Noise in measurement

I'm having a problem when I measure a voltage from a lead battery. I provide my circuit so you can understand better whats happening. For example I measure a 24 V battery, goes to a resistor divider ...
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3 votes
1 answer
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Voltage variation in the output of Differential Amplifier

I am working in low side current sensing differential amplifier circuit. VA is connected to ground and resistance R2 is also connected to ground but both the grounds are not same then there is voltage ...
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3 answers
89 views

Are Arduino inputs equivalent to voltage measurement?

I read somewhere that Arduino input pins basically (more or less) just measure the voltage at their pins with respect to ground (and then, based on that, create an analogue value or a digital HIGH or ...
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3 votes
2 answers
167 views

Is this op amp circuit a promising idea to measure 300VAC?

I need to measure 300VAC. I am using the following circuit and it is working good. In the circuit, I am using 2mA/2mA current transformer. More details about this transformer are available here. ...
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0 answers
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How do Fuel gauge ICs compensate for battery aging?

I came across this Fuel gauge IC recently and although I understand how the SOC is determined, I do not understand how the age compensation constant(the one used to determine the actual SOC) is ...
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What's the per phase equivalent circuit of induction motor with asymmetric windings?

We know that there's T equivalent circuit and inverse Γ-equivalent circuit for 3 phase induction motor(IM). When the IM is operating under normal situation, the windings are symmetrical, so all 3 ...
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5 votes
6 answers
618 views

Voltage drop over open circuit

I am still learning the basics of electronics and this confused me: I have a simple LED circuit like this (5V voltage source): The LED has a specified voltage drop of 3V, and is rated for currents of ...
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2 answers
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IV curve has non zero current in open circuit condition

I have an IV measurement program running in LabVIEW, where I measure the IV curve of a photovoltaic module using a programmable electronic load from a quick backward sweep (from Voc to Isc.) I have a ...
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Check if two voltages (with different grounds) are within 0.5 V of each other

I have designed the following circuit that should be able to detect if two voltages Bus Bar VBAT and VBAT that are referenced to Bus Bar GND and GND, respectively, are within 0.5 V of each other. On ...
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1 vote
0 answers
77 views

How to accurately measure average temperature of a heating element?

Problem I'm trying to very accurately measure the heat of a nichrome wire as current is passed through it. My approach thus far has been to monitor current and voltage across the heating element and ...
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3 votes
2 answers
169 views

Digital voltmeter reading half the voltage measured with Fluke multimeter

I recently purchased these cheap digital voltmeters from Amazon to display the output of my 2.5 kV HV supply. The HV supply has a dedicated 1/1000 output (0 - 2.5V)for monitoring, which I am trying to ...
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2 votes
2 answers
116 views

Voltage limit of differential amplifier?

I need to measure the voltage difference between two high-voltage points (~500 Vdc). I'm thinking of using a differential amplifier with a gain of 1/100. While it behaves as I want it to in the ...
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1 answer
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How do clamp multimeter sense presences of AC voltage?

If a clamp meter is taken near a AC supply line, it's AC voltage sense LED starts to glow. The same coil that is used for current measurement is used to sense the presence of voltage. As far as I know ...
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1 answer
71 views

How can I measure a battery's level in percentages using a voltage divider and an ADC?

I want to measure the battery level of 4 AA (R6) batteries using a voltage divider made of 2 resistors which goes into the internal ADC of a PIC16F microcontroller with a 10-bit resolution. Knowing ...
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3 answers
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Should ADC reference pin also be a kelvin connection?

Reasking this question with a proper schematic: I am doing a ratiometric measurement of a Thermistor. The thermistor is located over 5 metres away from the ADC and all other components. This is going ...
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1 answer
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What is the phase difference between phases in 3phase system, if system becomes unbalanced

Is the phase difference between the voltage phase 120 degree in an unbalanced system if not what how can we calculate it? I will try to explain this a litte more clearly. More specifically in this ...
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0 answers
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Help in understanding a Capacitive Voltage Transformer

I have been reading up about CVT’s and trying to comprehend some of the parts of the typical circuit which include: A potential divider (C1 & C2). An inductor tapped from the potential divider. A ...
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Vernier TDC: how to adjust every stage time differential to achieve 1 TLSB?

How do we get td1 - td2 = 2ns? I have no idea about how to adjust delay cell.
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60 views

How to measure the voltage of a battery under load to roughly estimate remaining charge?

I am designing a system where I'll need to use a micro controller to measure the voltage of a 12V lead acid battery to determine it's state of charge. I was planning to simply use a voltage divider ...
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1 vote
1 answer
195 views

Op-amp weird noise (asymmetric) [closed]

I have a discovery board and an ADA4528-2 op amp. These are connected together. PCB and schematic are in later. Acquired data from MCU ADC of stm32f746 is on the picture below. As you see the signal ...
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5 votes
1 answer
113 views

Why am I getting inconsistent voltages at op-amp's inputs in a simple DC amplifier?

I'm new to circuit design and am unable to figure out why I'm getting inconsistent voltage measurements under certain circumstances at the inputs of an op amp in a very simple non-inverting DC ...
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0 votes
1 answer
66 views

Impossible current readings while measuring motorbike lamps

I own a motorbike that runs with a 6V (yes, 6V) electric system and I'm designing some LED lamps for it. My current design is dead simple, here is a falstad simulation, it's just two 1W 2.5V drop LEDs ...
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0 answers
22 views

Query regarding MAX20480DATEJ/VY+ voltage monitor

I'm using a MAX20480DATEJ/VY+ voltage monitor for my design. Out of four inputs, I prefer to set IN1 2.5V at the same time for testing purposes. When I'm running my command, I'm constantly getting a ...
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2 votes
2 answers
147 views

Which theory do oscilloscopes or multimeters follow to measure RMS value?

For calculating RMS value , what I have found so far is that samples of a full cycle are taken then the ADC values are used to calculate RMS. Thus the RMS value stays independent of signal frequency. ...
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2 answers
54 views

Problem measuring waveform on an LED and a low side MOSFET switch

I'm trying to measure the waveform on the drain of a low side MOSFET used as a switch for an LED with an oscilloscope. I tried two different configurations with different components and power rail ...
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1 vote
2 answers
61 views

How to Determine Signal Voltage

How is a non-sinusoidal (I realize however all signals can be broken up into combos of sinusoidal waveforms) voltage measured? Let's say an interested party plays a standard shape G-chord on their ...
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1 answer
66 views

How do I display voltage on a Keysight DSOX1204G?

On page 37 of the manual, It clearly indicates the voltage in the top left hand corner of the screen DSOX1204G manual and hints that it would display the voltage for each channel next to the channel ...
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1 answer
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Can current transformer be used to sense voltage?

When searching for voltage sensing transformers, I've come across this device on the internet: ZMPT107-1. I far as I understood, this is a current transformer (it either uses a burden resistor or an ...
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-2 votes
1 answer
57 views

Testing on an intercom amplifier

I am trying to test a door phone intercom amplifier. How can I test that the amplifier is not faulty with a multimeter. I have a tested fully working amplifier and another faulty one. If I measure the ...
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1 vote
0 answers
78 views

Design-check; Finding practical accuracy of a DIY voltage-current-temperature meter

What I plan to do I'm building a DIY current-voltage-temperature meter. I felt the need for a mV meter, with a good accuracy down to 0.1mV, a mA meter with accuracy down to 1uA and an optional K-type ...
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0 votes
1 answer
62 views

Possible problems of AC energy metering using rectified waveforms

I'm building an energy metering circuit with discrete parts and precision is not a big deal in this case. One friend had the idea of rectifying both the voltage and current waveforms before sampling ...
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5 answers
197 views

Can I use 10A multimeter to test 445 watts solar panel

I want to know if I can use a cheap multimeter, model DT-830D, which has a maximum current rating of 10A to test voltage and amperage of a 445 watt solar panel with the following characteristics: <...
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0 votes
1 answer
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Connecting an Arduino to both panel and load side of charge controller, can this work?

I just joined this site because my searches haven't turned up an answer to this question, so apologies in advance if I missed something. I have an Arduino powered by the load side of a 12V solar ...
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