1
\$\begingroup\$

I am an absolute novice when it comes to electronics. I want to use a PC to control an Arduino UNO clone that will in turn control a strip of 122 neopixels. My fear is that I will somehow damage the PC.

These are the WS2812B LED strip and Arduino UNO clone I plan to use:

https://www.amazon.com/dp/B09736VKNN

https://www.amazon.com/dp/B016D5KOOC

This is the external power supply I plan to use to power the LEDs:

(5V 10A) https://www.amazon.com/dp/B08763VWXM/

My questions are as follows:

1. Should I wire the power supply to the LED strip directly or should I use the power jack on the Arduino UNO directly?

2. If I use power jack on the Arduino UNO what will happen if the LEDs are powered on and the external power supply is disconnected before the USB?

3. What do I need to do to protect the signal pins on the Arduino UNO?

\$\endgroup\$
3
  • \$\begingroup\$ >My fear is that I will somehow damage the PC. ... I too. So I use an isolated USB. And a "another" pc. Not my notebook. \$\endgroup\$
    – Antonio51
    Jun 21 at 7:54
  • \$\begingroup\$ Or alternatively, use a BT or Wifi transmission. \$\endgroup\$
    – Antonio51
    Jun 21 at 8:01
  • \$\begingroup\$ Counter questions : 1) Is the arduino you have rated to pass 8 to 10 amps via the PCB? Does the board have any manual, specs, datasheet or schematics to have info how it is supposed to be used? 2) It depends how you wired it or plan to wire it. We don't know unless you tell us. 3) Protect Arduino signal pins from what? It would help to know what protection it might need. \$\endgroup\$
    – Justme
    Jun 21 at 8:09

1 Answer 1

0
\$\begingroup\$
  1. Should I wire the power supply to the LED strip directly or should I use the power jack on the Arduino UNO directly?

You should wire it directly to the LED strip. The LED strip and the power supply form the "real" circuit. Whereas the arduino will be supplying only a low power digital control signal.

  1. If I use power jack on the Arduino UNO what will happen if the LEDs are powered on and the external power supply is disconnected before the USB?

The LEDs will draw excessive power from the USB port. The port would probably shut off due to internal protection. I don't think anything would be permanently damaged, but it's possible. Regardless, you are right to want to avoid this situation.

  1. What do I need to do to protect the signal pins on the Arduino UNO?

It's actually pretty simple. The arduino and the LED strip need to have their grounds connected, but they don't need to share a power supply.

  • First connect the LED strip directly to the 10A power supply with decent gauge wires, like 18-22AWG. This is the "power" part of the circuit.

  • Connect your arduino to the LED strip using 2 wires. GND, and SIGNAL. You can add a series resistor to the signal line for additional protection. A 1k will probably work.

Now one additional thing you need to look out for is ground loops. The ardino and led strip are connected by a tiny ground wire, and if the ground potentials of those 2 systems are slightly different, it will cause problems (probably unreliable communication). The simplest way to prevent this is to plug the power supply and the PC into the same outlet or power strip.

If you can't do that, or it's not sufficient, you can add an opto-isolator between the two signals, but don't worry about that until you've tried everythign else.

\$\endgroup\$
2
  • \$\begingroup\$ The answer is confusing. If you wire power supply to LEDs, they don't consume power from USB as USB power is not wired to LEDs. Arduino power jack can't be used anyway as it requires more than 5V input as it goes to regulator, which can't handle more than maybe few hundred mA. \$\endgroup\$
    – Justme
    Jun 21 at 9:13
  • \$\begingroup\$ And about ground loops, if both the PC and power supply are referenced to mains earth and not floating, and if the 10A ground return breaks/disconnects, the 10A tries to go through USB ground wire and via PC, likely vaporizing something on the way. \$\endgroup\$
    – Justme
    Jun 21 at 9:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.