Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [voltage-measurement]

Act of measuring voltage

1
vote
0answers
16 views

Using a switching DC-DC converter in high dynamic range current/voltage sensing

I'm thinking of making a power meter circuit which will have a high-side current-sensing amp (LTC6102), a resistive voltage divider for sensing the voltage, a dual op-amp (OPA2365) as a buffer for the ...
0
votes
0answers
57 views

Circuit that averages voltage

Suppose we have an oscillating signal V(t) with V(t) >= 0. I'm looking for a circuit that averages this signal over a given time so that I can read out the average value directly using a simple ...
0
votes
1answer
30 views

Voltage drop across buck converter

In my robot, I plan to have a GPIO pin on my Raspberry Pi connected to the insertion detection pin (pin 3) of a barrel jack (schematic here) so that my code can tell when the robot is externally ...
0
votes
2answers
73 views

Elimination of interfering voltage

I have a problem deriving a formula I will be using in my bachelor thesis. It's about eliminating interfering voltages during measurement. To understand how the interfering voltage is going to be ...
17
votes
3answers
2k views

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 ...
0
votes
3answers
323 views

The Ohm's law calculations of the parts do not agree with the whole

In the circuit below, the Ohm's law calculations of the parts do not agree with the whole: the voltage drops of the parts do not add up to the total voltage, and the current does not calculate to be ...
2
votes
3answers
72 views

How to measure voltage of each bank in a Marx Generator?

If I have a 10 stage Marx generator with each stage at 2.5kV, when I erect all the stages the last stage's negative terminal will be at 22.5kV with respect to ground. If I want a voltage ...
0
votes
2answers
44 views

DC test equipment to see voltage extremes? [closed]

I want to experiment with magnets and coils to produce voltage. I need test equipment to find the highest positive voltages and the lowest negative voltages obtained during tests. My needle driven ...
0
votes
0answers
49 views

20 kV 100 mA Voltage Current Sensor

like the title says, i need to measure 20 kV 100 mA line. For the voltage part i found this:http://www.koncar-mjt.hr/en/docs/koncarmjtEN/documents/61/1_0/Original.pdf and this:https://www.hivolt.de/...
5
votes
3answers
5k views

How do I measure a voltage greater than 5 V with Arduino? [duplicate]

I want to measure a varying voltage with an Arduino and real time data plotting has to be done. But the supply voltage will be 10 V and the Arduino is not supposed to have more than 5 V. Is there a ...
1
vote
1answer
46 views

Differences in voltage measurement at the input of a circuit

I am trying to understand the difference I am seeing in voltage signals, that I am applying to my circuit's input. So the basic layout is shown in the diagram, I have a connection, A from my function ...
0
votes
3answers
53 views

Power determination for resistive load

I am a mechanical engineering student and i need to measure electrical output. I have some voltage and current measuring instruments. I used them to measure the voltage & current of a blower(...
0
votes
0answers
44 views

How to connect photo-transistors to trigger Arduino event

I'm busy doing my finals project, and I need to have 5 photo-transistors come together on the same pin to trigger an event whenever one of these transistors drops it's voltage because an object is ...
1
vote
3answers
81 views

Possible reasons for differences in voltage between garage opener circuit and Raspberry Pi

I am attempting to use my Raspberry Pi's GPIO to activate a garage door opener (specifically Craftsman 139.5364812). As far as I can tell, the garage door is operated by shorting two terminal screws ...
8
votes
1answer
1k views

Is it normal for a lithium ion battery to read with a very low voltage on a multimeter?

I have a PS Vita and I suspect the battery is dead and needs replacing, as the Vita won't charge at all. But the issue could also be the charge circuit, as when plugging it in to charge the charging ...
1
vote
2answers
78 views

Non-intrusive measurement of current and voltage

Sorry if this question is too basic for this forum... I'm an interested amateur but far from a professional. I'd really appreciate information from someone more informed than myself. Hypothetical ...
2
votes
3answers
1k views

Measuring a small resistance, ~0.001 ohm

I have a low resistance resistor that I would like to use to measure the current through another circuit, but first I need to accurately determine its resistance. Its data sheet says it is 0.001 ohm +...
0
votes
1answer
32 views

What would happen if you measured voltage between power strip GND/neutral an external object?

Probably a totally stupid question but I'm a novice trying to understand fundamentals. If I stuck one multimeter test lead into ground or neutral on a live power strip with some things plugged in, ...
1
vote
1answer
153 views

Calculating a voltmeter reading

I'd like to preface with saying that I'm quite new to this. Given emf E = 9 V, and that both resistances are equal, R = 1 kΩ, ...
0
votes
1answer
135 views

Opamp Buffer output voltage offset

I am building a system which will measure and record the voltage of batteries. There are 8 channels in the system with each channel being capable of measuring 0-35V. The accuracy we have decided upon ...
0
votes
1answer
24 views

Trying to Build a voltage-driven smart shunt/threshold switch

I'm trying to build a smart DC switch that measures the input voltage (3V to 40V)1 and determines to which output pin to send it, similar to this threshold switch idea or a SIP3242 for Vin, not load ...
1
vote
4answers
249 views

Ultracapacitors as a battery; how long will they last?

I would like a formula to be able to calculate how long it would take 6 2.7v 350f ultracapacitors connected in series to degrade from 14.4 volts to 11.5 volts given a parasitic draw of a specific load....
0
votes
4answers
73 views

Oscilloscope coupling and effects on the measured signal

I have a basic understanding of the of coupling settings on an oscilloscope, but I need some help to understand what I am seeing on scope. I have a signal generator, with an arbitrary function set, a ...
1
vote
2answers
75 views

Voltage readings in Transistor used as switch

I have been trying to understand the operation of transistors for a while now. Today I thought to put what I learnt into test. Cutoff operation of a NPN transistor. As I read in one of the transistor ...
2
votes
1answer
96 views

Simple way to avoid current draw on resistor divider sense?

This is a simple, but complicated question. I measure voltage on several lines, more than 3'000. The lines can be up to 100V. I only need to measure at certain time, and would like to avoid current ...
-3
votes
3answers
263 views

How can I create voltmeter with Zener diodes?

simulate this circuit – Schematic created using CircuitLab 5 LEDS One LED is to remain always on when current is passed through. One LED will turn on when voltage is between 50 to 90 volts. ...
0
votes
1answer
45 views

Why is there a minimum input resistance?

I was looking at this multimeter, and it says, Output rate:     0.1 V/A (use with a device having a 1 M-ohm input resistance or higher) Where can I read why this minimum resistance is required? ...
0
votes
1answer
93 views

Invert Voltage 0-2V

I need to invert voltage from the one sensor. So the ting is that I have DC signal from sensor: 0%-100% range of 0V-2V I need: 0%-100% range of 2V-0V I have LM324 level indicator and it is showing ...
0
votes
1answer
85 views

Help simply the resistor usage in this voltage summer and divider circuit

Can someone help simplify the resistor usage in this circuit? VS is a constant 5v supply. Flex is a variable voltage between 0 and 5v. The resistors above have been brute forced to achieve this ...
0
votes
2answers
66 views

Is it possible to lower an ADCs input range?

I'm trying to use an ADS8504, a 12-bit ADC, and get as good a resolution as possible. The ADC accepts inputs in the range of +-10V. However, my circuit is limited to only having a power supply of 5V ...
0
votes
2answers
81 views

Question on brushed DC motor voltage measurement

I'm operating a brushed DC motor via PWM at 5 kHz. It's a big motor rated at 125V/27A. I don't have an voltage acquisition circuit. Just a multimeter. But I want my microcontroller to know what the ...
0
votes
0answers
60 views

Measurement of high voltage with low voltage circuit

Is it possible to make a high-impedance, precision measurement of a 10V DC signal (dynamic range requirement is only ±1V with a DC-1kHz BW) using amplifiers and an Sigma-Delta ADC supplied only by +3....
0
votes
1answer
47 views

Optimization voltage divider measurement

How to design a voltage divider to optimize the measurement error? Intuitively I would take the same ratio $$\frac{load}{divider} = \frac{divider}{measurement}$$ As follow: the voltage is roughly ...
1
vote
2answers
53 views

Measuring battery voltage in PV scenario with MPPT charge controller with inverter

So I'm doing a PV project with wifi enabled statistics. I'd like to see the watts coming in and out and the battery charge level, estimated battery charge and discharge time. I'm designing PCB to ...
0
votes
2answers
115 views

My multimeter probes are too big to measure a laptop battery

I'm having laptop battery problems, and the hardware manual gave diagnostic instructions involving measuring the voltage in the battery. So I bought a multimeter (never used one before in my life) and ...
0
votes
1answer
52 views

Multimeter temperature coefficient - Specified accuracy

I want to calculate the temperature coefficient for a digital multimeter. The datasheet I read it is calculated as: 0.1*(specified accuracy)/°C (<18°C or >28°C) Do you know what specified ...
0
votes
2answers
85 views

Voltage sense multi range - how to switch with no voltage drop

I have an application where I need to measure precisely (<0.05%) a voltage level which can be from 1V up to 500V. To do so, I use several voltage divider that are then multiplexed to a ADC. ...
-2
votes
2answers
148 views

Protecting against over voltage but with minimum leakage current

I have a circuit where I sense an input which is a voltage divider with resistor. Since the voltage divider needs to have high impedance, the current flowing through is in the range of 10's of uA. I ...
1
vote
5answers
109 views

What kind of tool is used to record a voltage over time to a PC file like a waveform?

I don't have any training but am doing some hobby electronics. I would like to record a change in voltage over time, sampled at around 100+ kHz. Ideally, I'd like to record around 20-30 min of two ...
1
vote
2answers
45 views

Measuring floating gate potential with minimal leakage current

I am working on a sensing device where the voltage of a floating node is dependent on the quantity to be sensed, as well as the net charge stored in the node. I would like the device to be only ...
0
votes
1answer
90 views

Can I add an INA219 voltage\current sensor to this USB powerbank?

I have a Raspberry Pi Zero in a small robot that I have been powering off a USB powerbank and it works great. Unfortunately when the USB battery goes flat the power is cut and the Pi crashes. I want ...
6
votes
4answers
2k views

Measuring AC voltage without a transformer using a microcontroller

As I have no practice with AC voltages, I'm asking if the following circuit is reliable for measuring AC voltages about 110Vca and 220Vca 50Hz/60Hz. I have already made it with a small transformer. ...
1
vote
1answer
64 views

Measuring input voltage with 3.3V ADC MCU

I am designing my very first DC motor driver circuit. Right at the start, I want to be able to measure the input voltage to the system. The system supposed to work with external DC power supply from ...
1
vote
1answer
92 views

Is it appropriate to use a 300V RMS CAT I rated oscilloscope to measure 230V RMS of a power inverter?

Yesterday I decided to look at the waveform of my portable power inverter. The inverter specs are the following: Input: 12 V DC Output: 230 V RMS Rated power: 300 W I powered my inverter from a ...
2
votes
4answers
51 views

Measuring SuperCap current leakage avoiding voltages drops in ADC

I have a circuit with a SuperCap used as a battery. I want to know the curve of SC voltage in time to finnaly measure its self-discharge. Is this can be done with a simple arduino or another ...
0
votes
1answer
102 views

How to determine DC input voltage of a device without its charger? [closed]

Had a MotoMaster (Canadian Tire) 27/3 LED flashlight for 4 years now. Model was discontinued 2-3 years ago. Lost the charger at least 2 years ago and the light's battery FINALLY died today (!!) I ...
0
votes
1answer
494 views

INA219 measure voltage of battery with RPi

simulate this circuit – Schematic created using CircuitLab I want to measure voltage of 12V battery powering something by INA219 connected parallel to this battery and read it with RPi via I2C. ...
0
votes
1answer
101 views

Is there some way to measure mains voltage with the ACS712 sensor?

Last year I went to a maker event where some guys used an ACS712 sensor with an Arduino to monitor the mains voltage and current to monitor the energy cost in the house. One thing I saw there is that ...
1
vote
2answers
209 views

Why do I measure (almost) no voltage between 230V phase and my body?

The other day I was experimenting with a multimeter and checked the voltage in one of the electric plug at home. Without surprise I measured around 230V between phase and neutral and also 230V between ...
0
votes
2answers
111 views

How come no voltage is meassured across my electrolysis tank?

I've built myself a electrolysis tank, using a plastic barrel as the container, rebar as the sacrificial cathode, a 12v 15A car charger (DC), and a Sodium Carbonate solutions as the eletrolyte. The ...