Raspberry Pi Stack Exchange
Raspberry Pi Stack Exchange

Questions tagged [voltage]

151 questions
10
votes
3 answers

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 used to trigger this warning, so that I can see how…
kabdulla
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8
votes
3 answers

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 put on the transistor. The only transistor I have…
user61421
7
votes
2 answers

TP1/TP2 equivalent for Raspberry Pi 3 B

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

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 RPi 4 operates on a lower core voltage than earlier…
Mtl Dev
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5
votes
1 answer

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 wtf is up with that? What does this require? I'm…
stefanw1337
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4
votes
2 answers

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 information about the presence of water. I tested…
Peter S
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4
votes
2 answers

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 programmatically. I did an initial bench test without the pi,…
CDog
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4
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3 answers

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: Supply voltage: 5 V Working current: 30 mA Max.…
GuiTeK
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4
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2 answers

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 with the yellow bolt - indicating low voltage.…
DisplayName
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4
votes
4 answers

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 kiloOhm resistor. 5V * 4700Ω/(4700Ω+2200Ω)= 3.4…
adriankroeger
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4
votes
4 answers

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 multimeter and it displays 5.2 V, suggesting that it shouldn't be…
Cai
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4
votes
5 answers

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 way to monitor the voltage of the battery pack…
mr_tuna
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4
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2 answers

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 drop and I can detect this. And if this still works…
Freygeist
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3
votes
3 answers

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 I need anything else? I've read this other topic…
SofaKng
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3
votes
1 answer

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. But I mistakenly touched -for a moment- a GPIO…
Mustafa Usama
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