4L.8 Transistor switch
Lamp: 0.15A, 6.3V
BJT: MJE3055
What is Ib?
I=U/R=5V/470Ω=0.010A=10mA
What is the minimum required β?
Current permitted by lamp=0.15A (Ic)
Ic=β*Ib
β=Ic/Ib = 0.15A/10mA = 15
Minimum β of MJE3055 is 20, so the transistor is saturated.
