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I use an ESP32 with a 3.3v->5v level shifter to send the info to the data line of a 150 led-strip (WS2812b).

It is recommended to use a 300-500 ohm resistor between controller's output pin and the strip.

But the problem is, if I add it, leds doesn't turn on and if I remove it, the leds turns on as expected.

Can I safely remove the resistor? I'm not sure if the level shifter is enough or adding extra resistance although don't see an additional voltage drop.

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    \$\begingroup\$ Yes, you can remove them. They can serve mainly 2 purposes: protecting your MCUs output, and possibly make the signal edges somewhat less sharper (less potential noise, etc). It is not clear to me whether you added the resistor between the MCU and level shifter or between level shifter and LEDs though. \$\endgroup\$
    – Wesley Lee
    Commented Feb 2, 2018 at 2:29
  • \$\begingroup\$ Hi @WesleyLee, added between level shifter and leds. Was thinking also in lowering it and try but not sure if any benefit. \$\endgroup\$
    – Mauro H. Leggieri
    Commented Feb 2, 2018 at 2:49

2 Answers 2

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It would be better to leave it in-it can prevent damage to the driving circuit if the ground bouncex below zero.

A lower resistance is better than nothing, but don’t cut it too close. If you have long wires running to the LEDs, put the resistor at the LED end.

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  • \$\begingroup\$ It is a 5 meter led strip (150 pixels). You are saying that putting the 100-ohm resistor at the end and to ground will have the same effect? \$\endgroup\$
    – Mauro H. Leggieri
    Commented Feb 2, 2018 at 3:21
  • \$\begingroup\$ IF you have long wires running from the ESP32/Level shifter to the LED strip, put the resistor at the LED strip end of the long wires. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Feb 2, 2018 at 3:37
  • \$\begingroup\$ But that kind of level shifter does not have a very strong pullup to +5 (10K) so it might just be the straw that's breaking the camel's back. \$\endgroup\$
    – Spehro 'speff' Pefhany
    Commented Feb 2, 2018 at 3:40
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This Might Help.enter image description here Wemos Lolin D32 With Ws2812B Led Strip.( With Logic Shifter )

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  • \$\begingroup\$ Hi @sagar, thanks for sharing. All new information is welcome. \$\endgroup\$
    – Mauro H. Leggieri
    Commented Jun 7, 2021 at 1:46
  • \$\begingroup\$ Are you sure this is correct? You appear to have VCC on the SN74HCT245 connected to 3.3V, so isn't the output of the B side only ever going to be 3.3V? (Conversely, you've got DIR connected to 5V, which now exceeds VCC) \$\endgroup\$
    – Alastair Aitchison
    Commented Aug 21, 2023 at 7:25

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