PNP BJT emitter follower circuit – Transferring weak signal voltage with a diode voltage shift

Bipolar Junction Transistor (BJT) emitter followers take a weak signal voltage, and transfers that voltage (with an approx. 0.6V diode difference) to the load while providing the needed power/current to hold that voltage across the load.

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Basic PNP emitter follower circuit properties:

Simple PNP BJT emitter follower bipolar junction transistor common collector circuit schematic diagram by electronzap electronzapdotcom
Simple PNP BJT emitter follower bipolar junction transistor common collector circuit schematic diagram by electronzap electronzapdotcom

In relationship to ground, the voltage at the emitter will be about 0.6V higher than the voltage you set at the base.

The load doesn’t go to ground with the PNP BJT emitter follower. Instead it is between Vcc and the emitter.

Therefore the voltage at the emitter is actually subtracted from the Vcc voltage as far as the load is concerned.

2N3906 PNP bipolar junction transistor BJT schematic symbol and pin layout diagram by electronzap electronzapdotcom
2N3906 PNP bipolar junction transistor BJT schematic symbol and pin layout diagram by electronzap electronzapdotcom

 

Video

Quick PNP BJT emitter follower common collector electronics circuit set by trimpot

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