PNP transistor for backlight

[elgerg]

Hi,

First off nice board! I've been making mine using perf board but yours is a much nicer and cleaner solution.

The one thing that I think might be lacking is the ability to control the backlight using a transistor. The reason this is important is that the BL uses 5v whereas the ESP is only providing 3.3v meaning the screen is a little dimmer than it needs to be.

Do you have any ability to update the design to add the transistor and resistor as required?

The transistors I have been using are the 2N3906 which would also require 2 resistors, one from pin 32 (~ 1k) to the base with a ~ 10k resistor between base and emitter.

Let me know what you think.

Thanks!
Alex

[DustinWatts]

Hi Alex,

On my ESP32 TouchDown board I am powering the back light through a transistor, but still from 3V3. The reason I did that is because of the current draw. I didn't want to draw the LED current through the ESP32.

https://raw.githubusercontent.com/DustinWatts/esp32-touchdown/main/Hardware/ESP32_TouchDown_Schematic.pdf

You can easily drive those LEDs from 3.3V with a small dropper/current limiter.

I might update the board in the future and do a better design, but I would still keep the board just a PCB without the need for extra components. I could include some footprints and have a cuttable jumper to initially bypass those footprints.