Solution to problem 2:

To determine RBL :

VBB = VCC - IRBL x RBH - VBE(ECL)

- 2.3 = 0 - IRBL x 0.35 - 0.75

IRBL = 4.428 mA

IRBL = [ VCC - 2 ( VD(ON) ) - VEE ] / ( RBH + RBL )

4.428 = [ 0 - 1.5 + 5.2 ] / ( 0.35 + RBL )

RBL = 0.4856 K