How to drive a LED Garland

Using Arduino Project Guidance
1

Hello there!

I started electronics quite recently and I am having so much fun! Yesterday, I decided to convert a poorly working solar powered LED garland to a battery operated, Zigbee driven garland!

Thanks to the ESP32-H2, the Zigbee part was a breeze but when I hooked my relay to the garland, I realized that only half of the lights were on. After some investigation, half of the LEDs are connected using one polarity, and the other the other polarity. I guess, it's a way to allow "light animations" using polarity switch. Why not after all.

However, I am having trouble figuring how to have all the lights turned on at once. I got the impression that I have to create a -3V / +3V square wave but I have no idea how to do it. My reseach shows that I cannot do this with an arduino only (can't I really?) and I am looking for a "not too complicated" way of driving these LED.

Any advice?

2

@madmaxime
You would generate the +/- voltage with a H-bridge circuit.
However, I'm almost 100% certain that there is no off-the-shelf module/board that will work at 3V.
You may be able to build something with a few ICs, resistors and capacitors on a breadboard if that is the way you want to go.

3

Hey @jim-p, thanks a lot for your quick answer!

A H-Bridge should work but it feels overkill especially when looking at the original board (the other side is only two buttons and one condensator):

IMG_1156
IMG_11561920×1227 237 KB

This very simple board handles:

  • The solar charging of the li-ion cell
  • On/Off
  • The switch between light animations (still, alternative, etc.)

I am pretty sure I am missing something and obviously the references on the ICs are nowhere to be found online...

4

With surface mount components and a custom PCB it would certainly be possible.
Is that what you want o do?

5

I want to drive these LEDs. Whether it takes a custom PCB or not is not really an issue thanks to our favorite Youtube sponsors (aka PCBWay) but first I need to understand how it works so I can recreate it.

Do you know what are the components in the pictures and what they do?

6

No but I'm sure that U2 or U3 is a custom IC for doing all the LED functions, that's why it looks so simple.
I'm not going to design a circuit for you maybe someone else would be willing

7

The key was a L293D IC, here is the schematics for the next one with the issue:

image
image751×617 46.4 KB

I will release the PCB Gerber file once I am done with it but since it's my first one, it will take some time :smiley:

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