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# Questions tagged [voltage]

Voltage is the difference in electric potential between two points of an electric circuit, measured in Volts (V). Voltage can be constant (DC) or varying (AC).

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23 views

### How much current needed to power arduino uno?

I am planning to build an rc car based on arduino uno. I will use 3S 11.1 V Li-po to power whole circuitry. So my question is; First, can arduino be powered directly with 11.1V from its Vin pin? ...
43 views

### Have I fried my arduino uno?

I made a smart dustbin using arduino, servo motor, & ultrasonic sensor. It worked pretty well for a few number of days. But once I don't know how but the Arduino 'ON' light started to become dim ...
238 views

### Detect power interruption on NodeMCU

Im using a 5v 1A power supply and connected to VIN pin on the NodeMCU. I also use 18650 battery to keep NodeMCU running in case the power supply shuts off due to power interruption. I'm planning to ...
60 views

### Why Arduino pins don't output 0 volt?

void setup() { pinMode(5, OUTPUT); } void loop() { analogWrite(5, 0); // or //digitalWrite(5, LOW); } Output is 0.003V and the tiny voltage causes the circuit to draw 20uA. Is there anyway ...
53 views

### Turn on/off low current device (LED) with Arduino

I am just starting with Arduino and my first project consists in switching a LED light with Arduino. I know a relay must be use to control AC high voltage device (i.e. 240V), however, as my LED seems ...
1k views

### Read frequency of input in digital pins

This is a somewhat theoretical question: Let's say I have some sensor that sends digital signals to one of Arduino's digital ports. Now, I don't know the frequency it sends those signals in. For ...
109 views

### Arduino Micro not providing regulated power

I have an arduino micro that works fine off USB. I need to power it from an external 12V power supply. When I connect the 12V supply to the adjacent VIN and GND pins, the arduino will not power up. ...
40 views

### Why voltage drop cause changes in analog reading of hall-effect sensor?

The sensor is a hall-effect UGN3503 sensor and I'm using a TL431 shunt regulator as voltage reference for analog readings. I'm using analogRead() with setting the analog reference to external ...
98 views

### Have I fried the voltage input on my Arduino Nano?

I tried using my Arduino Nano in a circuit, switched on power to the circuit and heard a crack and smelt a bit of burning - something shorted. I have plugged my Arduino into my PC with a USB, the ...
308 views

### Can I power a Wemos D1 R2 via the VIN and GND pins?

Can I power a Wemos D1 R2 via the VIN and GND pins? If so, at what voltage?
28 views

### 3.3v pin on a 5v Pro Micro?

I have a arduino pro micro that runs on 5v. I also have a Max4466 that needs 3.3v, however the pro micro doesn't seem to have a 3.3v VCC. Is there any way to attach the max4466 to the Board?
74 views

### Transistors to use for eight voltage sweeps from two PWM Arduino pins

On my Arduino Mega, there are two PWM pins open. There are eight analog voltage inputs to a datalogger. They are connected through a PCB, and I need test them with a DC voltage sweep. (There are many ...
37 views

### Load Resistor Use for Voltage Sensing by Arduino

I connected a piezoelectric film to a Arduino Uno board via analog input. However, as I was getting very high voltage values (reaching 5 volts without much movement). Therefore, I added a 1 megaohm ...
184 views

### measure +3V and -3V through resistor divider and switch on/off by digital pins

I've seen that resistor dividers can be used to read negative voltages, but I'ld like if there is a way to accomplish this with less components and having a way to turn this off. I was thinking if ...
71 views

### Handling arduino output current

I need to power an actuator that requires 12 volts and consumes between 5 and 10 amperes depending on the weight it is charging. Therefore I bought a power supply of 12 volts and 10 amperes. My ...
29 views

Usually when you sense AC voltage, you get a sinusoidal waveform. However, for AC voltage sources, Arduino analogRead ( ) only presents positive voltage values. So what's basically happening? Is it ...
52 views

### AC Voltage Sensing using Arduino Uno

Is it possible to sense AC Voltage using analog input for Arduino Uno or can it only read DC? I mean I've tried connecting an AC voltage source to analog and I'm reading some numbers. However, I don'...
35 views

### Maximum power rating for Arduino UNO revision 2 (SMD)

I have located the 5V voltage regulator chip on my Arduino board which I am hoping to use to power an attached device (which draws up to 500 mA at 5V). The chip is next to the plug for the external ...
260 views

### Voltage sensor Calibration

We had used a voltage sensor unit to measure the voltage of the odroid board using an Arduino Uno. wWhen I uploaded the sketch and got the output, the value which was being displayed was around 4.7 to ...
60 views

### Low voltage security

I'm building a circuit with a GPS sensor and an esp32. My input voltage is designed to be 5V but I experienced some issues where people put lower charger in input (<4V). As a result my esp32 will ...
237 views

### How to connect L298N motor driver to 5v input supply? [closed]

I'm trying to connect 5v supply to a L298N motor driver at it's 12V-35V input pin but it's not working. If I'm connecting to 7.2V supply it's working. Is there any way to connect 5v supply? I want a ...
231 views

### Connecting 5V arduino logic with 12V car logic

I need to connect arduino to K-Line in my car's OBDII port. I used an L7805 to power the atmega but how can I interface 12V car logic with 5V arduino logic? The problem is, the connection has to be ...
34 views

### Some noob questions regarding Arduino Nano based drones [closed]

Foreword: I am doing my Bachelors in Aerospace Engineering and part of the requirements to graduate (and get a good grade) is that I must complete 3 projects of my choice, and it must be unique. So in ...
227 views

### Generate a ramp input with an Arduino Uno

Is there anyway to generate a ramp input from an Arduino Uno? A visual depiction of the pulse I am looking for is as follows: With other microcontrollers, I was able to use their in-built DACs, ...
33 views

### How to measure multiple voltages (Thermocoupes)

How would one measure many (20-100) small voltages in the 0-80mV range with an Arduino? I will need to amplify them and put them into the ADC. But i also need to switch between them. I want to ...
29 views

### How do I supply either (1) dual voltage or (2) negative voltage? [closed]

Sorry in advance if this question already exists--I tried to search but my keyword knowledge is shaky. I have created a Colpitts oscillator on breadboard using AA batteries as the power supplies. I ...
147 views

### Measuring battery voltage [closed]

I am trying to use this way to measure my battery voltage at least approximately, but I am getting weird results. I am running breadboard atmega328p with internal 8 MHz and powering it from a LiPo ...
44 views

### Making a voltmeter for PV system over 60 VDC

I'm trying to make a voltmeter for my PV system that can range from 24 VC to 120 VDC. I'm aware of the fact that we have Arduino modules available that can work for 25 VDC system. However in my case ...
182 views

### Digital I/O threshold voltages for ATmega32u4

What are the voltages on a ATmega32u4 (eg Arduino Leonardo) such that a HIGH or LOW is read? I want to ensure that I'm reading the chip reference manual correctly, where Table 29-1 says: VIL: Input ...
255 views

### Arduino controlled light dimmer software

I found this software: /* AC Voltage dimmer with Zero cross detection Author: Charith Fernanado <a href="http://www.inmojo.com"> http://www.inmojo.com </a> Adapted by DIY_bloke License:...
26 views

### How to build an µC controlled power regulator?

The idea: Use an Arduino-like µC to control a set of CPU fans by control the voltage the CPU fans receive. My question: How can I do this in an easy way? Yes, I know, there is PWM but this is not ...
47k views

### NodeMCU - Vin pin as 5V output?

I know that Vin can be used to power the board but have also been reading that it can be used as a 5V output. Is it possible to assign Vin as an output as I would any other GPIO? If I want to power ...
67 views

### Arduino UNO socket

As I learnt so far is that Arduino UNO board has a socket for power input. The available power input range is between 7V - 20V, but the optimal usage range is 7V-12V. Here I am wondering: ---> if ...
1k views

### Difference between 3.3v & 5v

Im quite new to arduino in general and i'm sorry for the beginner question. could someone explain what the 3.3v and 5v on boards do? I know their voltages. but can you run one on the other? whenever ...
89 views

### How would I go about measuring an analog signal on my arduino mega that has both positive and negative voltages

I have a signal that fluctuates between -70mV and 50mV. How would I get the arduino to read this.. Ultimately I am trying to graph the data in real time so it looks like this. https://imgur.com/a/...
38 views

### Powering arduino and node mcu [closed]

I want to power up my Arduino and my Nodemcu via 12 V , 1 A power adapter (it's an AC to DC power Adapter). Recently I have two voltages regulators: a 5 V for nodemcu and 9 V for Arduino Uno. The ...
257 views

### Arduino DigitalWrite() Super Basic Circuit measure voltage with multimeter

I am having a problem measuring the voltage with a multimeter. I am not sure if arduino is even sending out a voltage from the Pin. I will try to create a really basic circuit drawing for reference. ...
114 views

### Can the Arduino be hurt by connecting too many LEDs in serial?

Today I learned about Vf for leds, after founding out that 3 leds in series driven by 5 V did not make them light up while 2 did. However, I also read that it is quite bad for a power source to use ...
92 views

### 3.3V from 5.0v outlet

I am working with an Adafruit Feather 32u4 FONA board. I want to connect a GPS module I have worked with before (3.3V required) but am not having much luck. I have studied the pinout of the board and ...
78 views

### How to produce multiple DC voltages for a single project

So the title pretty much says it all, but for an example, I have an arduino board, 5-12 V, an LED bank 18 V, and an ultrasonic mister 24 V. I know some brute force methods to power ...
1k views

### Convert from 3 V to 5 V

I'm new to Arduino, electronics, and this forum. I have made up a little project that connects an HC-SR04 ultrasonic range detector, and displays the distance on a 4 digit, 7 segment LED display. ...
33 views

### Different voltage sources across Vin and DC jack

So I understand that the USB VBUS circuitry turns off provided there is a high enough vin voltage using the PFET and comparator. I can see that the DC jack is connected to the Vin pin via a diode. ...
44 views

### Using a DFRobot Voltage Divider

I'm reading on the DFRobot website to implement this Voltage divider: Analog Voltage Divider SKU: DFR0051 void setup() { Serial.begin(9600); } void loop() { float val; float temp; ...
116 views

### Why does reading an analog pin give a different results when interfacing with Processing?

I am interested in measuring the voltage over an analog pin (A6). When I use the Arduino IDE to print the results through the serial I get values around 300. Here's the code void setup(){ Serial....
592 views

### Will Nodemcu support 4AAA

Will Nodemcu support 4AAA batteries which is 6v approx, or should i go with 3AAA batteries which is 4.5V approx. And one more question , is it ok to use AA instead of AAA ?
427 views

### Arduino Nano off 9V : is there any change to output?

I'm building a test circuit on an Arduino Nano that consists of a simple 220 Ohm resistor and an LED on pin D2 which is routed back to GND (ground). It's as simple as this: It's running a very ...
81 views

### Need Input: Wait for voltage input to begin script & when voltage maintains 0V for X amount of time Reset and wait for Voltage Input

So I'm currently working on an automotive set up. I'm using a 555 timer to emulate a turn-signal alternating voltage pulse (12V to 0V and repeat) for debugging purposes which is output to turnPin/A1. ...
116 views

### HC-05 3.3 voltage regulation

HC-05 Bluetooth RX requires 3.3 v (TX has a regulator built in) I understand my uno and nano are 5v Ive connected a 3.3v Zennor in series with a led and resistor and with multimeter established the ...