Neopixel rings have "magic behavior" - Functions without GND

[GrandTheftAuto4life]

...So I have picked up a box of various components locally few days ago from a guy who have lost interest in electronics.

Nothing interesting, except for these nexpixel rings that somehow is able to function when using only two pins.






Only VCC and DataIN is connected. GNS is not connected.
If i connect GND, these will only light up randomly and be very dimmed.

I assume it's able to seep back to my arduino mega when the dataIN pin goes low. but in theory this shouldn't be possible.

Can someone provide a better explanation?

[james_s]

That has to be exactly what's happening, you have to have a return path for the current, there's no way around that. The surprising thing is that connecting ground causes them to malfunction. Are you sure the input pins are labeled correctly?

[amyk]

It's definitely drawing power from I/O and ESD diodes. Dave has a video about this.

[GrandTheftAuto4life]

That has to be exactly what's happening, you have to have a return path for the current, there's no way around that. The surprising thing is that connecting ground causes them to malfunction. Are you sure the input pins are labeled correctly?

yeah. it's just something i've never seen before