# 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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### 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 ...
5k views

### How to know positive and negative in breadboard

I have this breadboard, and there is no indication on it about what is positive/negative on it. In comparison, this other breadboard (pic from the internet) DOES have indications: Can anyone give ...
157 views

EDIT: Here are the links to the sensor spec sheet (http://www.omega.com/temperature/pdf/HX71.pdf) and manual (http://www.omega.com/Manuals/manualpdf/M4543.pdf) for your reference. I'm using a ...
442 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 ...
512 views

### Measuring voltage from -12 to +12 VDC

I'm making a -12 to +12V DC regulated power supply, on which I want to measure voltage and current with Arduino (through a voltage divider, of course). I'm not sure, how to either detect nor measure ...
598 views

### How to create a smooth change in voltage?

We are given two voltages A and B between 0 and 5V. So how do I generate a smooth/continuous analog change in voltage from A to B in a predefined time? The current with that varying voltage is 1 ma ...
137 views

### Controlling voltage and current from chip?

I'm well aware that this question perfectly showcases my spectacular ignorance, but oh well. It's a simple enough question, so here we go. I have a 595 chip (SN74HC595) wired up to an Arduino, fed by ...
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. ...
8k views

### Reading pressure sensor using Arduino analog

I'm using a Arduino Uno to read pressure and I want to know if I have wired/coded the sensor correctly. I'm not sure I'm getting the correct readings (it could be the right readings - I just want to ...
746 views

### How to understand the “power economy” of a voltage up-converter (boost converter)?

My online video Arduino instructor makes use of various devices to amplify signals, currents, and voltages. This seems like magic to me. For instance, he has 4 AA batteries with 1.2V each. He says "...
173 views

### Lolin NodeMCU V3 and 5V sensors

I am new to Arduino and electronics so please correct me if I made a mistake. Many sensors and actuators require 5V. The Lolin NodeMCU V3 has outputs of 3.3V. I want to have them working together. ...
196 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 ...
75 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 ...
2k views

### How does Arduino digital input pin measure its input voltage?

Just starting with my first Arduino project. In order to measure voltage in a circuit I connected my multimeter to two points in the circuit (for example before and after a resistor). I am interested ...
2k views

### PWM water pump flow control - in percent

I want to control flow level on 12V water pump with PWM pin, I'm using IRF520N MOSFET for that (and dedicated 12V power supply). I'm assuming, that setting PWM to full byte should give me about 100% ...
34 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 ...
120 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/...
193 views

### How can I make an AC analog voltage with Arduino?

I am trying to create an AC voltage in Arduino. Until now I have only managed to get a square wave. How can this be achieved with Arduino? If I try: int up; int down; int out = 11; void setup() { ...
184 views

### Smart way to map digital pins to a for loop over analogue pins

First post here and I have very little Arduino/c programming knowledge so forgive me my ignorance. I am processing 18650 cells for a little powerwall project. I am using an Arduino pro mini ...
51 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 ...
43 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 ...
125 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 ...
989 views

### Ams1117 worked fine on battery, up in smoke with 12v power supply [closed]

I have a circuit that worked fine on a a 12v lead acid battery for a day. Once connected to a 12v 3a power supply it didn't work properly and then the ams1117 5v burned up and so did a 3.3v one within ...
47 views

### Thermocouple and multimeter

I've put together this script that should allow my Arduino Mega to be show thermocouple readings on the serial monitor, whilst also showing readings of voltage and ohms across a given component. I'd ...
72 views

### How to Measure many voltages (Uno) - Analog extenders a good option?

I am trying to make a battery capacity tester (3.7v li-ion 18650 battery) using arduino uno. If possible i'd like to test 20 or more batteries at the same time. I need to measure the voltage of each ...
251 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....
167 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. ...
318 views

### NodeMCU ESP12 Voltage

I'd like to power an NodeMCU off of four 1.5v batteries. That's 6v. Depending on the source I've read that 5.1v will fry the board and, just a few clicks later, that the board will take up to a 20v ...
415 views

### I have cooked 3 regulators applying 12 V to RAW pin. Am I doing something wrong or did I get a bad batch?

I'm trying to make a simple keypad lock that has a 12 V magnetic lock. I supplied 12 V to the RAW pin on the Pro Mini with plans to actuate the relay with the 5 V from VCC pin. The lock was grounded ...
548 views

### Using voltage divider to read voltage from sensor

Good morning, I would like to use an Arduino Duemilanove to read the voltage signal generated from a current sensor (CSLA2CD). The datasheet for this sensor can be found here. The problem is that ...
231 views

### HC-06 RX pin usefulness

I have a HC-06 bluetooth module. The module has an RX and TX pin (the RX pin receives data and TX transmits data) which connect to the TX and RX pin of an Arduino respectively (in my case an Arduino ...
157 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 ...
39 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 ...
215 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 ...
815 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?
90 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 ...
74 views

### ADC pin shutting off on its own under certain condition

A0 pin not working when full PV system in use I am using the DFRobot Leonardo with Xbee R3. I am using the A0 pin to read a 0-5V voltage from my voltage sensor, which samples and steps down 130VDC ...
2k views

### Power Arduino with 12V while using Serial Communication over USB

I'm going to build a 8x8x8 Led RGB Cube, therefore I will need a lot of Power which the arduino can't handle, so I'm using a 12V 20A (I know 20A isn't necessary but I had one laying around). So the ...
144 views

### Automotive Lighting Control Module

I am looking for an Arduino-based solution for an automotive lighting application. System Requirements: Able to Operate in Automotive (Interior) Environment (12 +/- 2V DC Voltage) Minimum 3 12 V ...
1k views

### Logic level converter not working?

I'm trying to connect a 3.3v depth sensor to an Arduino uno. The logic level converter does not seem to send any current over (the sensor does not work and the voltmeter reads nothing). I tested the ...
133 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 ...
45 views

### Arduino voltage connection pins

On the Arduino power connector jack, which is the positive terminal pin and the negative pin?
73 views

### How to get the overall average of the data received

I have an arduino uno with two sensors. Voltage and current sensors. I need to get the average value of voltage and current each time the data is received. But i don't know how to add up the current ...
77 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 ...
39 views

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

The idea: Use an Arduino-like ĀµC 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 ...
39 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. ...
3k views

### Combining code for multiple sensors (Current and Voltage Sensors) in one program

I need to operate 2 different sensors (Current and Voltage) simultaneously. I have managed to run each one of them separately and I don't know how to manipulate the code so they could work together. ...
325 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:...