Transistor characteristic plotting

The circuit described here makes use ot a computer to plot the so-called output characteristic and determine the small-signal current gain, hfe, of an n-p-n transistor. These two transistor parameters are ot great importance tor classifying an unmarked transistor, tor a reliable good/faulty test, and for selecting matched transistors trom an available lot. Although the program that controls the circuit is written tor the Atari ST series of home computers, the use ot the Centronics port should enable owners of other micros to adapt their own version fairly easily.