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I am trying to drive an LED strip (10 LEDs) from the output of an ESP8266 GPIO pin. I measured the short circuit current from the GPIO and got around 40 mA. My question: Is it recommended to include an emitter follower stage to isolate my ESP8266 and my load (LED strip)? I don't want my load to draw a large current from the MCU pin which could alter the logic level.

A crude circuit is shown below (component values are not as per calculation)

schematic

simulate this circuit – Schematic created using CircuitLab

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You do it as simple as this:

schematic

simulate this circuit – Schematic created using CircuitLab

The 1kΩ resistor at the base of the transistor feeds about 2mA@3.3V into the small signal NPN transistor, that's enough to saturate it for a collector current of up to 100mA. If you need more than that, consider a darlington NPN instead. VLED may be up to 50V or so, whatever your small signal NPN offers.

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