# Transistor current source \beta varies (AoE Ex. 2.23)

I am having trouble solving the following exercise:

Exercise: If $$\ \beta \$$ varies from 50 to 100 for collector voltages within the output compliance range, how much will the output current vary? (There are two effects here).

First one effect should be early voltage. Output compliance should be 0V to about 8.9V ($$\V_E = 1V\$$ then collector is 100mV above emitter if there is a 8.9V voltage drop across the load). There is a formula in the book for the effects of early voltage: $$\I_c = I_{c0} (1+ \frac{V_{CE}}{V_A}) \$$ where V_A = 50V - 500V (see p. 93)

So with this I could in principal calculate my 'new' collector current.

Question 1: How can I use my varying $$\\beta\$$? I have the strong feeling that simply doing things like $$\I_c= \beta * I_B\$$ is not the way to go (what is $$\I_B\$$? ). The load current in this example should be 0.67mA. So I could calculate $$\I_B\$$ with this when I assume a certain \beta.

Question 2: What is the second effect?