littletransistor
New Member
Hey there,
I'm doing a small revision of BJTs - and including the difficult Darlington pair calculations. Oh - I'm not asking for any answers - I did my homework already, but I got stuck into a point. Any assistance will be very great.
Okay, the question asks me to find the current gain. Here's what I come up so far:
V base = 4 V where Vcc * (R1 || R2)
V emitter = 4 - (0.7 * 2) = 2.6V
Overall beta ac is 150 * 100 = 15000
the emitter current IE is 1.733mA from 2.6V/1.5K
total of input resistance (Rin ) is 33k || 22k || 15000*1.5k is 13.192k
and input current Iin is 1V / 13.192K = 75.8 micro amps
Current gain = 1.733mA / 75.8micro = 22.86.
And unfortunately, the answers in the book reveals 8.8. Any which part I'm missing?
I'm doing a small revision of BJTs - and including the difficult Darlington pair calculations. Oh - I'm not asking for any answers - I did my homework already, but I got stuck into a point. Any assistance will be very great.
Okay, the question asks me to find the current gain. Here's what I come up so far:
V base = 4 V where Vcc * (R1 || R2)
V emitter = 4 - (0.7 * 2) = 2.6V
Overall beta ac is 150 * 100 = 15000
the emitter current IE is 1.733mA from 2.6V/1.5K
total of input resistance (Rin ) is 33k || 22k || 15000*1.5k is 13.192k
and input current Iin is 1V / 13.192K = 75.8 micro amps
Current gain = 1.733mA / 75.8micro = 22.86.
And unfortunately, the answers in the book reveals 8.8. Any which part I'm missing?