I am working on a project that involves a Raspberry Pi 3B+ and multiple sensors (temp/humid DHT22, pH probe and EC probe from atlas scientific, cameras....).

I am trying to figure out how to power my sensors using an external power supply as I faced many issues with the Pi, with it shutting down whenever I run my python scripts for a while. I tried to narrow down the problem and found that it wasn't necessarily a software issue that I am aware of so the only logical explanation is a power supply issue. That is why I started to outsource the power supply away from the Pi for a bunch of sensors. Now I have found this helpful but I do have a question to make sure I got this right and I don't screw my system up: Power multiple sensors with external power source

  • What does Mohamad mean when he says to connect the GND from the Pi directly to the Negative line of the barrel jack? I understand that the sensors need to have a common GND but couldn't I just connect the sensors to the external VCC (barrel Jack) and the GND to the Pi directly?
  • So clearly from my previous inquiry, I have much to learn! After much reading, I figured out that, yes, you need to ground your entire circuit. So if you want to connect sensors, pumps or anything together and want to perform according to your specs, then make sure they are all grounded together. Connect the GND of your power supply with the GND of the Pi. From what I understand, this applies to all DC circuits regardless of voltage (not sure whether it translates to higher voltages than 12V as that is what I tried so please take it with a grain of salt until you verify for yourself).
    – pharaouk
    May 24, 2018 at 21:45

2 Answers 2


This sensor works from 3.3V to 6V. If you are using it with raspberry pi then use the 3.3 V pin of raspberry pi.


Do you have an ammeter? what you could do is separate all sensors from the Pi and measure their current first; then measure the current of the Pi itself. Also if you have a voltmeter please keep an eye on the voltage you are offering the Pi, anything below a certain value (say 5V) may cause it to shutdown or reset.

Your case seems to be one of an underpowered power supply, but I may be wrong.

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