bjt-current_source-poor PUBLIC

Not provided.

A bipolar transistor makes a "poor current source"

AoE, page 73: "collector current varies very little with collector voltage (it behaves like a not-too-great current source)".

Even though the resistor is varied from 1 .. 20.000 Ohms, the current through the transistor changes only from 1,3 .. 0,5 mA. Factors of 20k vs. 2,6! (A perfect current source would show a straight line, having a factor of 1.)

n.b.: As stated in AoE, page 72: "A circuit that depends on a particular value for beta is a bad circuit." This is confirmed by this case: The beta ranges from 160..55! Furthermore, AoE, page 74: "You can expect [beta] production spreads of +100%, -50%."