# Questions tagged [voltage]

Voltage, otherwise known as electrical potential difference (denoted ∆V and measured in volts) is the difference in electric potential between two points (adapted from Wikipedia). Voltage can be constant (DC) or varying (AC).

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### Electrical circuits homework

I am pretty new to circuits analysis and I have the following problem as homework: ig2(t) = 4sin(ωt + π/4), e3(t) = 12sin(ωt + π/4), R1 = 10 Ω, ωL1 = 4 Ω, ωL3 = 3 Ω, 1/(ωC2) = 6 Ω I have to calculate ...
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### Convert [-24V,24V] range analog signal to [0V,3.3V] range for ADC

I need to realize a circuit that converts an analog signal from [-24V,24V] to [0V,3.3V] before sending that signal to an ADC "MCP3208". I found the circuit in the picture below and it works perfectly ...
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### Output voltage not stable - What is compensation with respect to DC-DC (buck converter)?

EDITS: Input voltage range: 24V to 48V. Changing the load current from 0.38A to 1.018A increases the mean output voltage from 12.779V to 13.26V. The supply should be producing 12.5V. I'm using this ...
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I built a circuit around a ESP32 powered by a LiPo battery (I tested with 1800mAh and 4400mAh batteries), a MCP73871 to charge it and a TPRT9080 to regulate voltage. When I use the ESP32 without Wifi, ...
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### LDO voltage regulator malfunctioning as passthrough after 24/7 usage

I have designed a custom pcb utilizing the ENC28J60 ethernet chip to be used with raspberry pi. The board has 5V in which powers both the ENC28J60 (through a AMS1117-3.3 LDO regulator) and the pi. ...
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### How to interface buzzer with LED in this circuit

Below is the circuit where I want to integrate the buzzer with the red LED. The task is to add the buzzer, where the red LED is, in such a way that when the red LED (which is driven by the LED driver)...
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### Is it possible for one oscillator to drive two ICs?

I have this oscillator IC with which I plan to drive a KSZ8795 and an LAN9500A without clock buffer. The TG2016 output load drive is 10pF for the capacitor. The KSZ8795 can have a crystal load ...
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### Is 1800A a realistic current for a mains wire?

(Moved this question from the Physics SE since it's apparently not suited there) I recently encountered this elementary physics question: A mains wire outside your house is 15m above the ground. The ...
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### How to indicate an android tablet is actively charging with LED?

I am a rank beginner, and I do feel like I am missing something pretty obvious here, as the problem doesn't seem that complex. (I know... famous last words) Problem: Android tablet (in a completely ...
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### LM339 LED voltage indicator behaving opposite of expected

I have built the attached circuit and am pretty confident it is correct with no short circuits. When it's powered up with a 9V battery, all 4 LEDs light up with no input voltage. As the input voltage ...
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### frequency of MCP3008

I built BOOST CONVERTER, I sample the output voltage with A/D and control it using RASPBERRY Pi3, I set the switching frequency of the BOOST CONVERTER 70KHz, and the frequency of the MCP3008 1.35MHz, ...
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### Arduino Every Nano with 3.7V Li-Po - Reading voltage

I have Arduino Every Nano and 3.7V Li-Po battery (Akyga LP903759). I want to read the current voltage of a battery using analog pin. If I use a 50 kOhm and 200 kOhm resistor (in voltage divider) I'll ...
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### 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 ...
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### Activating a relay when certain voltage received (Water injection system)

I decided to build a simple water/methanol injection system for my car and now I'm thinking about a simple way to activate the water pump only from certain boost level. For the boost reading I'm ...
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### PSpice VSIN frequency - how to set it in rad/s?

I know, that if I want to set FREQ, I need to set it in Hz, not in rad/s. I know, that 1 Hz = 2*pi rad/s, but how to do this in PSpice? What should I enter exactly? and btw. if I want to set VOFF (...
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### Estimate susceptibility of circuits to external electrical field strength

I will be soon testing a product to an electric field spectrum requirement (i.e. in the 100's of dBµV/m vs MHz), and it shouldn't be a problem because of how small the values are compared to the ...
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### If I were to run a motor slower, would the battery drain less?

This might be a dumb question, but I'm using a 48 V, 18 Ah battery to run a 48 V, 1800 W brushless motor. I calculated a predicted 34.6 min runtime at full throttle, however, I need it to be able to ...
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### Crystal Load capacitors & ESR

In the KSZ8863 datasheet, the crystal specification is given (table 9-3), page 85. Here the ESR is specified to 40ohms with no minimum nor maximum marking. Load capacitance is specified to a max of ...
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### Can I use a voltage divider instead of an external battery with an SCR?

I have this circuit 12VDC battery boost converter up to 390V DC-DC capacitor 1000 uf 450V diode 10A10 thyristor BTW69-1200 (I gt 8-80 mA / V gt 1.5v max) I managed to make this circuit work with an ...
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### Connecting digital ground and chassis ground

I have an Ethernet connector whose chassis or shield ground I need to connect to the digital ground. I read that it is a practice that is followed in many designs. My questions: Why should they be ...
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### ESD problem and how to solve

We have a problem with contact discharge of 3kV on a housing part. The PCB with the PHY are installed in an aluminum lower part with plastic upper part (dimensions approx. 80x80x80mm). The contact ...
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### Will this Battery Voltage Monitor with on-the-fly calibration work?

I am trying to make a voltage monitor for my RV battery as the one included with the RV is not very accurate. I would like the result to be accurate to +/-0.01V and intend to use an ESP32 and ...
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### Use 24 AWG to jump LED strip tape?

I have 12 V LED strip tape, actually running with a 9 volt source. I need to use a short amount of wire to connect two strips. I've seen some people use 22 AWG stranded, but I would prefer to use 24 ...
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### How can I graph the bias voltage vs capacitance in ADS?

I am trying to model a bias tee and control the capacitance of the varactor by varying the voltage. How do I plot the voltage vs capacitance/charge in a graph in ADS using AC simulation?
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### How to prevent voltage spike from BLDC motor in ESC circuit

I'm implementing the circuit below by modifying it using STM32 (Bluepill) and adding some decoupling capacitors (100nF) to the bluepill and LM339 with the supply from the battery also connected to the ...
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### Can I use a 1-phase analog electric meter rated for 230V to measure 120V current? would my readings be off by a factor of 2? or would it fail?

I am buying some cheap german 1-phase analog electricity meters and plan to use them in Central America. the german meters are rated for 230V and feature the old turning disc mechanism. In central ...
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I'm fairly unexperienced with electronics, but I'm currently working on what should be a relativly easy project, but I have a few questions and maybe you can help me. I recently found an old beard ...
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### What voltage difference should I use for 10BASE-T?

Looking through some resources about the electronics behind ethernet, specifically the 10BASE-T standard, I've found some conflicting information about what the voltage differential should be for the ...
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### Supply turn-on voltage spikes - best practices for protection

The problem I recently had a situation where a board had a destructive fail event from turning on a 53V battery which appeared to have had a voltage spike at least over 80V, most likely well over 100V,...
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### What is the effective value of the current of the voltage generator?

I need help with this task, if anyone had a similar problem it would help me. The task is: A voltage generator is connected to the primary of an ideal transformer, transformation ratio n rms values ​​...
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### Question about outdated "amplidyne" technology

Can someone please help me understand something better about "amplidyne" technology that was used back in the day. What I know It appears to be a dc motor generator that acts like an ...
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### Auto Voltage Selection between 12V and 5V for Irrigation Controller

Background I am working on a hobby project, it will be a general purpose open source irrigation controller. I haven't built the PCB yet but I want to power the board either through the USB port for ...
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### Differential Signal Measurement best practice

I have 4 differential signal pairs (LVDS Data lines and Clock) running between my Microcontroller and TFT. There are no test points over the lines. Can someone tell me what is the best practice and ...
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### Beginner trying to resolve transistor issues

I have designed a basic transistor circuit with the EveryCircuit simulator. The idea is that when the switch is open, one LED comes on and when the switch is closed the other LED lights up instead. It ...
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### Circuit operation

I have the below input protection and filter circuit. I want to understand how it works. Can someone tell me the purpose of R0101 and D0102 and D0104? As far as my understanding level, when the ...
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### Buck converter current

I have this synchronous buck converter. Input voltage - 8.7V Output voltage - 5V Switching frequency - 350kHz to 450kHz Output load current is 2A Schematic: I have an input capacitor of 68uF and an ...
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### Solar panel simulation for 7 solar cells in series

I have this question about the circuit that I am working on for quite long and it is just not working. Please help, i have already tried every thing i could understand. I followed a YouTube tutorial ...
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### Best way to manage multiple 12V inputs and outputs from Arduino?

For a bowling alley I am going to make a circuit using an Arduino Mega to turn on arrow lights(1-4 bulbs in each) given the bowling pin lights that are lit up at the moment on a masking unit. AMF no ...
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### Is capacitor voltage coefficient a function of frequency?

I have learned that the value of capacitance in a capacitor can vary slightly compared to nominal based on the voltage across it. This is called voltage coefficient of capacitance (VCC) It is actually ...
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### Why does my lightbar draw more current when connected to a battery than a power supply

When I measure the current draw of the lights when connected to a car battery, they draw about 2.4A However if I connect the lights to a 12V power supply, they only draw around 0.8A. Even though the ...
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### ESD Capacitor Calculation, 330Ohm Series Resistor and ESD Clamp Voltage

I have a input power filter circuit. It has ESD Protection capacitors which help to protect the downstream circuit from ESD Pulses. ESD Capacitors Specifications : C0001, C0002, C0003, C0004 = 47nF, ...
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### Strange levels on UART TX

I am trying to get the boot chatter from a UART on IOT device. When powered up TX line goes high as expected (3.3V), but when it starts "talking" - scope shows that hi/lo levels swings are ...
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### Replace USB diode with something else to reduce voltage drop

So I've made this circuit with a MOSFET and an Op Amp to select a voltage input to my battery. I sort of based it off the voltage selector circuit on the Arduino Uno board, but inversed since that ...
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### Voltage sensitivity coefficients for unbalanced radial distribution feeders

I am wondering if my implementation of voltage sensitivity coefficients for unbalanced three-phase-four-wire radial distribution feeders is correct. We got $\bar{V}$ for phase(s) of all the buses ...
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### PCB with Mixed Analog and digital

I am in the process of designing a new ADC\DAC PCB with a digital interface and analog front end. I have tried to separate the different grounds in my circuit to reduce the noise as much as possible ...
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### ADC in STM32F103 drops ouput voltage from unity buffer

I'm building a signal analyzer based on STM32F103RB6 placed on a noname board with the following schematics: I'm trying to normalize the AC input signal initially centered at 0V. The amplitude is 2....
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### Is the quantization error and random error included in the of-range error for multimeters?

When I am looking at a datasheet for a DMM (Digital Multimeter) to calculate the accuracy of a measurement it specifies two error sources: of-range and of-value (also called of-reading). For example ...
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### MOSFET Gate driver - negative voltage with Zener circuit

I was reading about minimizing MOSFET switching loss when I came across an article by Texas Instrument on how to use negative voltage, instead of ground, to faster discharge MOSFET gate capacitance. ...
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