# 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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### 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? ...
42 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

### 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 ...
144 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 ...
338 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 ...
245 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 ...
102 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 ...
47 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; ...
589 views

### PC Fan Speed Control [closed]

I am working on a project to blow air gently through a number of pipes and variable speed. I would like to use a standard PC case fan and have control of whether the fans are on/off and also what ...
1k views

### CH340 3.3v stability

I want to use the 3.3v on a cheap Arduino Nano clone as my ADC analog reference voltage. The 3.3v comes from a regulator inside the CH340 USB serial chip. I've measured the voltages (My DMM is NOT ...
2k views

### Powering a DC motor with an external battery

I'm working on a project where i need to control a 6 volt motor with an Arduino. The motor that I'm using requires 6 volts so I'm using a 9 volt with a voltage divider to get those 6 volts. My problem ...
578 views

### Connecting ACS 712 30A to my Solar Panel with Arduino

I am trying to connect my Solar Panel (array of 2 x 265Wp 24v panels connected in series) to my Arduino UNO R3/Nano so that I can make a current/voltage measurement system that can be connected to the ...
24 views

### Logging PAR with quantum sensor and Arduino

I want to link a PAR quantum sensor (either Licor or Skye Instruments) to Arduino to log PAR, in order to measure light in a forest. I have an Arduino Uno + data logging shield (with RTC, SD card and ...
36 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 ...
60 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 ...
508 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?
304 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 ...
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 ...
125 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 ...
51 views

### Designing around Output pin limitations

I'm new to Arduino and am working on a project with my son. We are using the LillyPad USB board (schematic) to drive a bunch of LEDs (LED Datasheet). Our project is based loosely off of the 'Turn ...
115 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. ...
15 views

### Attempted to disable autoreset - now the voltage regulator only outputs 4.0v

I followed the guide from the Arduino website, by placing a 10uF capacitor between GND and Reset. However, now the voltage regulator only provides 4v (Vin=13V). It correctly has 5V when being powered ...
434 views

### Too low voltage on digital input on attiny45

I'm using one of my attiny's pins as digital input. I use it with a pulldown resistor. As input I use simple square wave generated by a separate waveform generator. igh state for square wave is 5V, ...
201 views

### Max current per pin is 40 mA. But it is always 40 mA?

I need to calculate resistor for a PNP transistor. To do this I need to know the voltage and current. I know voltage is 5 volts as it is easy to find in the internet, but how about current? I mean ...
48 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 ...
275 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. ...
56 views

### need at least 5 volts but 3.7 lithium polymer battery does not supply enough Voltage

I am building a device using an Arduino Nano, an OLED display and infrared thermometer sensor. I want to make it rechargeable so I am using a 1 cell lipo battery and a tp4056 circuit protection board, ...
32 views

### Batteries and amps in parralel [closed]

So, i am about to buy a brushless motor a ESC and a 18650 batteries for my arduino. The batteries "specs" is 3.7v and 20a, if i would to put 2 and more in parallel would i get 7.4v 20a or 7.4v 40a? ...
48 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 ...
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 ...
104 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 ...
903 views

### Understanding schematics: resistors attached to Attiny85 pins V-USB

I'm currently trying to create my own Attiny85 usb thumb(to mimic an joystick). I understand that I have to limit the voltage on the attiny's pins that are connected to the D+/- pins from the usb. In ...
100 views

### Multiplying the voltage output

I'm working on a project where my arduino is receiving a voltage 0-5V, I need the output to be 10V always. Is there a way to do that?