Questions tagged [voltage]

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8
votes
3answers
9k views

Calculating resistor value for transistor

I'm creating a circuit with an infrared led and a transistor connected to a gpio pin. I'm currently using 5v with a 40 ohm resistor (four 10 ohm resistors chained) but I'm not sure what resistor to ...
6
votes
2answers
6k views

TP1/TP2 equivalent for Raspberry Pi 3 B

Is there "old" TP1/TP2 equivalent for Raspberry 3 Model B to measure voltage?
6
votes
3answers
23k views

Get reading of RPI supply voltage

On the most recent pi I've been playing with I've noticed the under-voltage lightning bolt warning, discussed on this question. My question is whether there's a way I can access the voltage reading ...
5
votes
1answer
2k views

Undervoltage symbol

So I have this undervoltage symbol on my raspberry 3+, and it's annoying. Now I have a powerbank with 5V and 2.1A(fast charger) and the symbol is there as well as on the old pi-2b+ AC adapter. So ...
4
votes
4answers
1k views

Voltage monitoring of battery pack (i.e. before voltage regulation)

I am looking to use four 18650 batteries and a step-down DC-DC converter to power my Raspberry Pi 4. The negative terminal of the DC-DC converter is common for the input and the output. I would like a ...
4
votes
3answers
2k views

Powering a sensor using an external power supply board

In my Raspberry Pi project, I need to measure a distance. To do that, I have an ultrasound sensor called "AJ-SR04M" (it is basically a waterproof HC-SR04 I believe). Characteristics of the AJ-SR04M: ...
4
votes
4answers
4k views

Raspberry Pi GPIO input voltage Limit

I am doing a project in which I have a component that outputs a 5 Volt signal. Since the Pi is only able to handle 3.3 V I connected the signal to a voltage divider. I used a 4.7 kiloOhm and a 2.2 ...
4
votes
2answers
1k views

Reading Voltage Input on ADC

I'm thinking of using the Waveshare ADC board with a RaspPi 3 to monitor the current driving a DC brushless motor. I've run through the waveshare examples, and I can handle reading inputs ...
4
votes
2answers
2k views

Water Level Detection Sensor 3.3 Volt vs. 5 Volt

I'm using a classic Water Level Detection Sensor or sometimes called Rain Water Level Sensor together with a RPI 3+ to detect water in a Pot (Link). So I don't need any analog reading but only the ...
4
votes
2answers
4k views

Pi 3 Model B+ doesn't boot - Power Supply or broken?

I just bought a Raspberry Pi 3 Model B+. I also bought a power supply that the reseller sold specifically for the Pi - it delivers up to 3A. However, the Pi doesn't boot. I gives me the rainbow screen ...
3
votes
2answers
4k views

What happens to the GPIO voltage after shutdown?

I don't have a Raspberry Pi laying around at the moment and I would like to detect if my Raspberry Pi is shuted down. My Idea is that maybe after the Pi shutted down the Voltage at the 3V3 pin will ...
3
votes
1answer
115 views

Raspberry Pi's reaction to 7.2 Volts applied to a GPIO pin?

I was using a Raspberry Pi 3 model B in a project. The Pi was connecting to a web socket and receiving data from the user on a PC or whatever device connected to the same socket. It was fine at first....
3
votes
3answers
2k views

What is the correct (internal) voltage range for a RPi 4?

When running vcgencmd measure_volts on older RPi's, a normal reading is 1.2v However, on my new RPi 4, the voltage reading is: 0.8648v Does this indicate a power issue, or is this normal, and the ...
3
votes
4answers
464 views

Low voltage warning despite using official power supply tested at 5.2V

I bought the Official power supply but when I use it in my Pi 3 model B I get a warning saying: "low voltage, please check power supply". I have checked the voltage on the Pi using a ...
3
votes
3answers
984 views

GPIO to detect if external 5v source is turned on or off?

I'm using a Pi Zero W and I'd like to connect a 5v source to a GPIO pin to detect if the 5v is on or off. I know the GPIO is only digital I/O and 3.3v max, so is a simple voltage divider enough or do ...
2
votes
3answers
886 views

Rpi Reading MCP3008 10 bit ADC Result Problem

I want to measure some battery voltage in a range 0V-4.2V with MCP3008(VDD=VREF=3.3V). I used a voltage divider with R1=2.7MOhm and R2=8.2MOhm, but it didn't return correct value, I used resistors ...
2
votes
2answers
1k views

Convert 12V to 5V to power RaspberryPi

I have an Eleksmaker laser cutter which has a board with a 12V output (see top of image). I would like to power my RaspberryPi using this 12V output. What is the advantage of powering the ...
2
votes
1answer
2k views

GPIO Voltage tolerance for input

I have not been able to find the input tolerance on I/O pins, especially on the Input pins. If I apply a voltage 3.6v (3.3v +0.3) on an input will it be dangerous or is it ok ? Does somebody have a ...
2
votes
3answers
917 views

Detecting 5v from external source using voltage divider

I'm working on detecting whether or not an external 5v supply is on or off and found a few helpful related questions, specifically this one: Detecting 5V output from USB charger via Raspberry Pi From ...
2
votes
2answers
146 views

raspberry pi fan don't start to spin without hand help!

Raspberry Pi has recently added fan control feature in its raspi-config tool. This made me curious to add a fan to my RPI 4. I did it recently with a 680-ohm resistor, 2N2222 transistor, 1N4007 diode, ...
2
votes
1answer
63 views

Use Raspberry with two devices that require 3.3v pin

I'm planning a project with an RFID reader that connects to the GPIO pins on a RPi2 and will use the 3.3v pin. Additionally I wanted to add an active buzzer, which also would require an 3.3v pin. Is ...
2
votes
2answers
130 views

Measure Volt, Amps, Watt and Kwh of an external 12V system

I saw online some cheap hardware ~10$ that can measure Volt, Amps, Watt and Kwh and display the results on an LCD screen. I could buy and plug these on my 12V solar panel system to monitor it. (5 of ...
2
votes
2answers
590 views

Voltage on undefined GPIO pin

If I do not specify the output of GPIO pin (like GPIO.output(4, False)), I always have a voltage of 1.3V on this pin How can I set all pins to 0v? and why are undefined pins have this voltage of 1....
2
votes
1answer
820 views

GPIO pins are always low

I'm using a Raspberry Pi 3 Model B running Raspbian Stretch Using it somewhat like an RC car with an L298N H-bridge motor driver to control two DC motors. It was working fine until a few days ago ...
2
votes
1answer
480 views

How can Rpi I2C read a Coulomb Counter, up to 18V, 10A?

I"m building an autonomous boat with a solar panel. The heart of the boat is a Raspi zero which contains a small program doing the navigation. I've got a 3S li-ion battery of which I'm already ...
2
votes
1answer
61 views

Cannot detect interrupt properly on a pulled up line

This is my simple setup simulate this circuit – Schematic created using CircuitLab This is my test program, using nodejs and rpi-gpio. var gpio = require('rpi-gpio'); gpio.on('change', ...
1
vote
1answer
485 views

Raspberry Pi 4 - Booting with 3 USB attached Harddrives causes Crashing

I use my Raspberry mainly as a fileserver. I've attached 3 harddrives, 1 of them being an SDD and 2 Mechanical 3.5 Drives. When powered on, everything seems to work. However, when booting, the initial ...
1
vote
3answers
89 views

Voltage dropped significantly on GPIO 4 with a relay coil

I have a Raspberry PI 3 B+, and when I activate the GPIO 4 as output and checking agains a multimeter I get its 3.3V as expected. If I connect the GPIO4 to one end of a coil (http://www....
1
vote
2answers
143 views

Slight dip on the GPIO 5v line when LEDs are on

I have my raspberry pi set up to do two main things: control 16 LEDs via 16 transistors each connected to an out pin. The LEDs are collectively fed the 5V from the GPIO. power a chip also on the 5V ...
1
vote
1answer
243 views

Supply voltage 5V issue from Raspberry Pi 3

I have a sensor connected to a Raspberry Pi 3 and I see some variations of the signals which is not expected. These variations seems to be due to the supply voltage 5 V from the Raspberry Pi. ...
1
vote
3answers
31 views

Avoiding voltage drops when simultaneously using multiple DRV8833 motor drivers

I am using three DRV8833 motor drivers. The power supply is currently a usb cable with the ground and power connected to a breadboard with the three motor drivers attached to them. When powering all ...
1
vote
2answers
409 views

can undervoltage damage Pi 3?

I was running a Pi 3b model from an "insecure" power source, aka unknown car radio USB, no idea how many amps it gives. but the lightning symbol appeared on the HDMI screen, then the screen flicked a ...
1
vote
1answer
264 views

Issue with a 12v switch via GPIO output

I am a beginner when it comes to electronics so I would appreciate your help with a simple project I am working on and have been struggling with for several days. The idea is that I have a PIR Sensor ...
1
vote
3answers
1k views

How can Rpi GPIO read the 12V output signal from a Guardline Security Alarm?

My new Guardline Security Alarm can send a 12-volt output signal to an accessory device. I would like to send that signal to my Raspberry pi and have it send an email to my iPhone. I bought a SMAKN Dc/...
1
vote
1answer
306 views

AC Current sensing giving low readings (SCT013)

So now that I feel comfortable with using ADCs, I am attempting to measure the AC current with the SCT013 clamp with AC current sensor. Setup: I clamp the SCT013 around the HOT wire of a table lamp ...
1
vote
1answer
110 views

Wiring that won't damage my pi [closed]

A while ago, I decided to wire up a Raspberry Pi (Zero W) to a few peripherals, but it stopped working shortly afterward (not entirely, but I think it was undervolting the power rails). I had ...
1
vote
1answer
840 views

Precision of Raspberry Pi GPIO outputs voltages [closed]

Raspberry Pi has several output voltages, GPIO outputs theoretically giving exactly 0V for False and exactly 3.3V for True, 3.3V line and 5V line. However, how precise are these outputs? Can the ...
1
vote
1answer
1k views

3.3v to GPIO input using relay

I'm exploring various ways to detect higher voltage using the Pi and have come up with a circuit where the 5v would energize the coil of a relay which would switch 3.3v from the Pi's internal 3.3v ...
1
vote
1answer
36 views

Programatically Establishing When RPi Supply Voltage is Too Low

Responses to this post: How does RPi "know" when it hasn't got enough power indicate that there is a digital input somewhere on the RPi which indicates what the supply voltage has ...
1
vote
1answer
105 views

Can Rpi GPIO pins be used to drive a DC motor? [closed]

I tried to GPIO pin to high and I cannot see output voltage. I try every solution but no one works for me. import RPi.GPIO as g g.setmode(g.BOARD) g.setup(16, g.OUT) g.output(16, g.HIGH) I look GPIO ...
1
vote
3answers
114 views

Best voltage for a Raspberry Pi 3B

I have 5.0V 3A and 5.2V 3A regulated supplies that I can repurpose for my Raspberry Pi 3B project. Am thinking of using the USB power jack. Which should I go with? 5.2V would seem to be within the ...
1
vote
1answer
185 views

powering a sensor usin external power

I' m not electronic or electricity specialist , i'm a developer who tries to make fun stuff on raspberry pi , and this is why i burned two rpi 3 . i'm using my rpi with many electronic stuff , pir ...
1
vote
1answer
47 views

PowerBoost 1000 5V with a 3.7v LiIon/LiPoly battery

I am very new to electronical components, and I am not sure if I can do the following: I am planning to start a project where a RPi Zero W would record 720p and/or 1080p videos (60fps ideally, else ...
1
vote
2answers
128 views

do RPi3 3.3/5V pins output constant voltage even if the RPi power supply is changing voltage?

I want to power my RPi with a lithium ion battery. The RPi will be powering some devices which require constant voltage to power them. If I use a battery as supply for the RPi (which changes as it ...
1
vote
1answer
4k views

Seeed ADC (ADS1115) with Raspberry Pi 3 B+to read voltage values using python3

I'm using a Seeed 4-Channel 16-Bit ADC (ADS1115) for Raspberry Pi with a Stretch installed Raspberry Pi 3 B+ and successfully configured following below guidelines & GitHub. http://wiki....
1
vote
2answers
289 views

Ground running back through logic shifter?

Sorry if this is a silly 'beginner' question, but I'm still only just getting into working with the Pi. I have a Pi Zero that I want to use to drive a module of a few WS2812 LEDs. Because the GPIO ...
1
vote
2answers
888 views

Rpi interfacing MCP4725 12-bit DAC pproblem

I am using raspberry pi 3. I am trying to run the AC induction motor for that I want an analog pin. In raspberry pi model doesn't have an analog pin. All pins are digital IO pins. So I have tried MCP ...
1
vote
1answer
677 views

Inconsistent i2c bus address listings causing sensor reading issues

I am using a raspberry pi 3 with an Atlas Scientific DO sensor to try and create a wireless sensor network for an aquaponics system. Everything works fine when I am running the system in my home in a ...
1
vote
1answer
52 views

LEDs won't follow pattern (voltage issue?) with Pi 3

First and foremost, let me say that I'm new to electronics and the Raspberry Pi. I'm a programmer. I have never done this type of project before. Now, I have a Raspberry Pi 3 model B that controls my ...
1
vote
2answers
3k views

How to check if 16x2 LCD is 5 volts or 3.3 volts?

I got a 16x2 LCD display but I have no clue if it's 5 volt or 3.3 volt logic. I'd like to use it on a Raspberry Pi but I'm afraid to just plug it into the 3.3 volts if the display is 5 volt. The ...