Bipolar junction transistor BJT simulating adjustable forward biased diode voltage circuit fragment

A bipolar junction transistor can be made to simulate diode with adjustable forward voltage. I learned of this really cool circuit fragment while reading the book “The art of electronics”.

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In order to do so, all I had to do was apply a divided collector to emitter voltage to the base by using a 2 resistor voltage divider. In that way, I was able to adjust how much voltage the transistor blocked by simply varying the value of the collector to base resistor. The video below shows the testing I did.

Video tutorial

The video below can also be watched by clicking the following link. 2N2222 NPN BJT wired as a variable forward voltage drop diode bipolar junction transistor


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