Questions tagged [voltage-measurement]

Act of measuring voltage

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1 answer
50 views

High current/voltage power monitoring in small form factor

I am attempting to build an I/O board to integrate with software I have running on a Raspberry Pi 4. I need the board to monitor voltage and current (power would be a bonus) on 8 circuits running ...
-1 votes
0 answers
44 views

ADC reading unstable at high current [closed]

What could be the reason and possible solution, for my ADC measurement on the microcontroller increasing more than the actual values, when high current is going through the circuit? I had just ...
1 vote
2 answers
854 views

Op Amp for DC Voltage Measurement

I'd like to measure 0-800VDC using the ADC of a PIC18F and opto-isolated from the high voltage. Since optocoupler's CTR is variable and non-linear, I'll use the IL300. Checking this application note, ...
3 votes
1 answer
532 views

Where does the 1 V voltage come from?

I have a PLC with many digital open collector outputs connected similarly to the schematic below. If I use a multimeter and measure the voltage between the two points in the schematic, it is showing 1 ...
0 votes
1 answer
480 views

Connecting multiple voltage sensors with the STM32 Nucleo board

I want to connect multiple voltage sensors to the nucleo board. Lets say 4 voltage sensors of same kind with same address. So, I thought I could connect all the 4 sensors with the nucleo board with ...
0 votes
1 answer
36 views

Coax cables, impedance matching and BNC extensions

I'm trying to understand how to do proper measurements with a Voltage Differential Probe ( TT-SI 9010. This probe has an output impedance of 50ohm and has a BNC (It doesn't specify it in the data ...
1 vote
2 answers
1k views

touch sensor for metal door handle

I was thinking if a current is applied to a metal door handled and somebody touched it that should complete the circuit to ground and be detectable but I'm not sure if this would work as the 'somebody'...
0 votes
1 answer
670 views

Monitoring external battery voltage with ESP32

I'm trying to monitor a battery that is unrelated to my ESP32. The battery powers my gate and the ESP32 is powered by POE. The battery is a 12v battery. I am using a voltage divider and the ADC to ...
1 vote
2 answers
99 views

Microcontroller that can do 10 UART? [closed]

I am currently working on a project that would require a total of 10 UART (rx and tx pins) to run 10 PZEM-004Ts for different electrical lines. I am thinking of using an atmega 2560 because it has ...
2 votes
2 answers
286 views

Measurement of high voltage

For research lab work, we use a high-voltage generator to create one pulse with a low intensity (< 4 mA). The voltage range is variable from 100 V to 3000 V and the FWHM of the pulse is ~1 ms. The ...
4 votes
4 answers
23k views

How to measure mains AC voltage with an ADC from a microcontroller?

I want to measure the Mains voltage (230V/50Hz) using an ADC channel from a microcontroller. This is my current approach ... Below I have two schematics that add two voltages (one direct, one ...
0 votes
2 answers
85 views

Why might my circuit's measured voltage drop when I add more load to it?

I have one of these power supplies: I also have an MCR-4V data logger: If I connect wires directly from the power supply to the data logger (red to red, black to black), then the voltage output on ...
0 votes
0 answers
24 views

On working principal of the low DC voltage charger of this certain behavior

How is the simple working mechanism or principal of the DC stage of a typically low DC voltage, ~ 5V, charger with the behavior: if a MM simply testing its voltage it gives 0 volt if a battery is ...
-1 votes
3 answers
118 views

Circuit for averaging AC voltage

I made a rl multivibrator with square wave output. The ton and toff of rl changes with magnetic field around. Normally the wave is symmetrical but on passage of magnetic flux, the pulse width changes ...
0 votes
2 answers
356 views

AC to DC conversion, how to keep the voltage same?

I have an amplifier board. The maximum input voltage is -40V 0 +40V DC. I have a 30V 0 30V 5 amp transformer. When I read the DC voltage after rectification, it shows around -45V 0 +45V. So what is ...
2 votes
1 answer
312 views

How do I scale a differential signal

I am trying to automatically measure the behavior of a batch of devices in order to guarantee that the current stays in the expected range for different supply voltages. For that purpose I am using an ...
0 votes
0 answers
32 views

Flyback transformer -measurement of average voltage

Consider buck-boost converter using self-osc. driving, in critical conduction mode, so the duty changes according Vin and Load. Does measuring the Vx as it is shown between collector and +Vcc, ...
4 votes
1 answer
180 views

How to check the high voltage of a electrostatic device?

I want to build a device with two metal plates which needs to have 3000 VDC between them. The way that I am thinking is to use a ferrite transformer from a 9 VDC transformer with a transistor that ...
0 votes
2 answers
501 views

Isolated voltage measurement with an ACS37800

I am measuring 250VAC with an ACS37800. It happens to be a PWM based output of a TRIAC. For testing purposes, I am varying the duty cycle and input voltage to validate the measurement circuitry. My ...
0 votes
2 answers
264 views

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

I'm doing a PV project with WiFi-enabled statistics. I'd like to monitor the power coming in and going out, the battery charge level, and the estimated battery charge and discharge time. I'm designing ...
3 votes
3 answers
457 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 ...
0 votes
2 answers
80 views

How to perform Kirchhoff's Voltage Law on an open circuit? [closed]

I am wondering how to perform KVL on an open circuit. For V_s = 10V, I have determined the V across R2 to be 10 Ohms but am confused about R3. The algebraic sum of the voltages around any closed loop ...
10 votes
2 answers
2k views

Reasons not to use these leads

I found the following note with a set of test leads we use for our Agilent 34461A[1][2]: This Test Lead Set is designed for use with the Agilent 34xxxA Multimeters, and also the U274A, U3401A, and ...
0 votes
2 answers
36 views

KY038 sound sensor: Voltage to SPL

I'm writing code to measure frequencies with a KY038 microphone sound sensor. It uses an LM393 voltage comparator. How do I convert voltage to sound pressure level (SPL)?
0 votes
2 answers
68 views

Measure transformer real power

I’m new at making transformers myself, and the ones that I designed had the correct output voltage, and when they were connected to batteries (previously rectified), they give me a an approximate of ...
0 votes
1 answer
59 views

What type of galvanometer is in this picture?

Does anyone understand the galvanometer in Faraday's experiment to the left in the picture below? How does it operate? It looks like it uses a magnet and some xy axis the needle swings over or maybe ...
7 votes
6 answers
4k views

Are there any tricks for measuring high voltages (~1000 V) efficiently?

The simple way to measure voltages above VDD is to use a resistor divider. However, once you get into the 100s of volts these dissipate significant power. For example, one of my current designs ...
0 votes
0 answers
61 views

Uncertainty for measuring a resistor

I am trying to calculate the uncertainty of a measure on a resistor. The expected value of the resistor is 45 mΩ. For measuring the resistor I used the two following instruments: SM500-CP-90 Agilent ...
1 vote
1 answer
2k views

ACS71020 Connecting and reading voltage properly

I am using an ACS71020 3.3 V I2C version hooked up to an ESP32. I have connected the IC as proposed in the datasheet. Rsense used is 1.8 kΩ as proposed in the evaluation board user manual for 230-240 ...
2 votes
2 answers
195 views

Why is the voltage across the LED negative, when the entire drop is positive?

I was changing the control board of my 3D printer. When testing the heatbed, I saw that the LED wasn't glowing (as with the old control board), when the heatbed was turned on. So I investigated with ...
0 votes
2 answers
138 views

How to extract voltage and current from this real-life circuit (with resistors)

I recently measured some voltages across two resistors as you can see in the images below. I used a triangle wave as voltage source and measured the voltages across the resistors with an oscilloscope. ...
0 votes
2 answers
314 views

Why would my true RMS multimeter give me a different AC voltage reading than my scope at frequencies above 2 kHz?

Here’s the circuit and my problem. My function generator is simply parallel connected to a multimeter and my scope. No load is connected and I am not using a scope probe, just a BNC connector with ...
0 votes
1 answer
52 views

Output voltage not changing with a constant current driver

If I attach a voltmeter to the output of this constant current driver and lower or raise the input voltage (100-230V,) the output voltage remains constant at 56V. Should it not fluctuate between 40-...
2 votes
2 answers
382 views

Which is the best method to measure AC voltage?

I am trying to make a UPS circuit. I need to have a high speed measurement for the input AC voltage (220 Vrms) (in order to know whether to turn on/off the inverter). I had tried using this circuit: ...
0 votes
0 answers
58 views

Which filter to use when measuring the voltage power line, common mode filter and/or differential mode filter?

I'm using an 78M6631 IC for three phase metering. For voltage measurement, the datasheet recommends a voltage divider. Researching through internet is recommended to include a filter, I don't get when ...
0 votes
4 answers
129 views

Isolated voltage measurement circuit or sensor

Which circuit or sensor can measure a voltage range of 24 V DC (the power supply for a motor)? The circuit is fully galvanically isolated from the ESP32 used. Does anyone have any ideas on how to ...
1 vote
4 answers
2k 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....
1 vote
1 answer
59 views

Current leakage when measuring battery voltage via Raspberry Pi and MCP3002

I have a project involving the following components: Raspberry Pi Zero W MCP3002 (Datasheet) Adafruit PowerBoost 500C (using a TPS61090) The Setup: The MCP3002 is connected to the Pi via SPI0 (pins ...
11 votes
9 answers
2k views

Is it feasible to measure voltage drop across 0-ohm jumper resistors to determine excessive current draw?

We design very low-power devices which in standby mode use about 8 µA of current. They are powered by 3 V lithium primary cells and are designed to last for many years. Every now and then we see a ...
3 votes
4 answers
1k views

Max amps and voltage CAT5e

I have CAT 5e running throughout a house. Trying to use the wiring to connect a CCTV camera. The camera says it uses 500 mA and needs a 12 V adapter. I do not know if it needs a full 12 V to run. I ...
0 votes
3 answers
189 views

Eliminating Negative Voltage Pulses (≤ 840 mV)

I have obtained a voltage signal from a Weigand sensor (a sensor that creates a low voltage signal when placed in a rotating alternate magnetic field), which generates a positive pulse of 1.2 V and ...
0 votes
0 answers
84 views

Parallel/Series Resistors Voltage measurement

I want to know the value of the resistors here. There are three conditions in this picture. Its getting really hard to fulfil the correct resistor values. Thats why i decided to post it here
3 votes
4 answers
4k views

Measuring voltage across 1 ohm resistor

This might be a very stupid question, but I can't seem to figure this out and I'm going nuts thinking about it. Assuming you are trying to adjust the fixed bias of a tetrode push pull pair in a tube ...
0 votes
0 answers
74 views

How to capture a damped sine wave with an oscilloscope?

Basically what I'm doing is feeding a resonator with a sine wave at roughly 1 MHz coming from a signal generator for a certain time T. After that, I'm switching off the signal generator and what I ...
0 votes
1 answer
72 views

PAC1921 power monitor issue

I'm trying to measure voltage, current and power by PAC1921 IC. This is a PAC1921 datasheet: PAC1921 DataSheet This is my schematic: 3.3V_Input is input from simple AMS1117 3.3 V regulator and +3.3 V ...
1 vote
0 answers
111 views

INA226 Vbus voltage reading has a 1.5% error on all measured voltages

I have an INA226 module with a 0.1 Ohm shunt resistor, here's the schematic: Device powered from 3.3V (ESP32 regulator's voltage). Since I only wanted to test the voltage monitoring function, I ...
0 votes
1 answer
84 views

Observed voltage unexpected in simple test circuit with one resistor

I have a 1.65v regulated source (max 50mA). I'm observing 1.71v with no load. I've added a 178 ohm resistor (verified with VOM). I'm observing 1.60v 9mA across the resistor pins. V = IR; V = .009A x ...
1 vote
0 answers
58 views

Measuring 12V car battery voltage precisely from the output of an ideal diode controller

I'm designing a device that will be plugged into the OBD2-port. One of the features is reading the battery voltage on demand directly from the diagnostics port. In order to protect the device from a ...
0 votes
2 answers
79 views

Comparator as a current detector with shunt resistor v2

I have a comparator with a shunt resistor that measures the voltage and when the voltage of 12 V from the source exceeds the Vref (1 V in my case) it switches to "high" output. I would like ...
3 votes
3 answers
4k 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 category of methods one can include ...

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