Brief NPN BJT emitter follower set by trimpot using 2N3904 bipolar junction transistor

Table of Contents

Emitter follower using the NPN bipolar junction transistor, outputs 0.6V less than the input voltage that we give it. The input voltage just needs to provide a very small amount of current, so it will hold it’s voltage really well no matter how much current the load needs. The BJT will provide the power needed for demanding loads.

Diagram

Simple NPN bipolar junction transistor BJT emitter follower set by trimpot divider schematic diagram by electronzap electronzapdotcom
Simple NPN bipolar junction transistor BJT emitter follower set by trimpot divider schematic diagram by electronzap electronzapdotcom

Emitter resistor and load builds up the voltage at the base with a 0.6V difference. It will be 0.6V less than ground due to the base to emitter diode drop.

The current through the emitter resistor and load will depend on their resistance (and voltage drops if applicable).

The emitter resistor is not always needed. Some loads however will throw off the voltage without the emitter resistor, so it is best to just always use one.

Video

Quick NPN BJT emitter follower set with trimpot voltage divider using 2N3904 transistor

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