What’s everyone’s feeling about how I’d go running signal to WS2812Bs over 3-4m of 0.75mm^2 unshielded cable?
(Normal domestic power cabling—+/- 12V on two conductors, 5V signal on a third. I know, I know, don’t cross the streams 
Would I get away with unshielded cable at these distances? Plan on using 4-pole Neutrik connectors at each end, and using 74HCT245s to shift up from the Teensy’s output.
I run my clocks on 3x0.34mm^2 on 3 meter unshielded USB cables. Works just fine but don’t turn on all led’s at full…
I’m not so worried about voltage drop as I am signal interference. Are you sure the USB cables aren’t shielded?
(These are also going to be running on a stage, possibly a more RF/electrically noisy environment than where you’d typically have a clock set up
yep, positive. signal interference is less a problem. most problems are caused by voltage drops and spikes on the voltage lines. fast switching led’s cause huge spikes. use capacitors on both sides of strip. “insert” extra power on long strips.
@Robert_Atkins A while back, I did some quick tests with a 30 feet ( ~ 9 meter) of 3-wire unshielded 22awg wire. (I don’t know what that is in mm²) but it is too small for domestic power cabling.
At the far end I only had a single WS2812 LED but it worked great. The voltage drop on the +5Vdc was about 0.3 volts. If I had just a few more LEDS, it is obvious that my +5Vdc drop would have made this setup totally unusable but the data signal itself was OK for that long length (that is really what I was worried about!)
In my opinion, unless you somehow picked up a lot of noise from external sources, you should not have any problems.
Awesome @JP_Roy , thanks for the data point.
@Robert_Atkins Since you did not mention the number of WS2812b, I assumed that you were not worried about DC voltage drop on the power carrying wires. You may need to modify that setup if you plan on powering a lot of LEDs.
my led string is fed with 30 feet of 3 core .7mm mains wire. no problems so far.
@JP_Roy Yeah, I’ve got a good story for that—running 12V through the long cables feeding a 5V, 10A DC-DC converter right next to the strips.
@Robert_Atkins yeah, that’s what the Xmas lights crowd do. Local DC 2 DC conversion. Where the signal does fade, they use a null pixel. I.e a driver chip, but no led.