Logic level shifter with 12V strip

Hardware
1

Hi,
I’m trying to improve reliability of a 12V WS2811 strip, I’ve got WLED running fine, but am getting pulsing of brightness (which is turn is borking things as it overloads my PSU, ignoring any current limitations I have set and resetting my ESP8266 in the process).

In terms of where to put the shifter I’ve got (BSS138), and its direction, I’m at a bit of a loss, I’ve basically just cut the gnd and signal lines and put it between them, with the HV side on the Wemos and the LV side on the strip. But this has resulted in the strip not functioning.

logic-level-shifter-setup
logic-level-shifter-setup1920×886 242 KB

Any advice appreciated.

Hmmm, just saw this topic, maybe it’s not the right hardware for the job?

1 Like
2

Use wiring instructions and recommended shifters from KB.

3

Your shifter have no power from low side and high side.

1 Like
4

And that kind is likely too slow.

5

Note, just to avoid damage: the level shifter is the same SN74AHCT125N as for 5V Leds.

6

2 Issues I can see (have not played with one of these btw) I think your meant to run the 12V to VH and 5V to VL and then run the data through the device connected from the Wemos to VL1 and out to the strip on VH1. so you have it backwards and you dont have voltage lines connected, and the data is in the wrong place.

7

THIS IS NOT CORRECT FOR ADDRESSABLE LEDS!.

All addressable protocols are 5V regardless of whether your LEDs need 5V, 12V, 24V, etc. VH should NEVER be higher than 5V for your levelshifter. You risk destroying your LEDs otherwise.

Unfortunately (as others have mentioned) your BSS138 based shifter is likely to cause more trouble than it solves. As per the Knowledgebase, use either a TXS0108 or (preferably) a 74AHCTxxx based device.

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Ahh, ok, but still need need to run the shifter as 5V on high side, see: [SOLVED] Wemos D1 mini - 5v and 3.3v pins - Microcontrollers - Arduino Forum

9

Yes of course, that’s the whole point of a levelshifter in the 1st place, change the ESP3.3V GPIOs to 5V (ONLY 5V) compatible for the LEDs.