#### circuit975

##### New Member

I am faced with such a question

1) Calculate and determine the value of the resistor RE that will ensure that VC=6 V.

2) Redraw the transistor model of the equivalent circuit for small amplitude AC signals. Determine the voltage gain Av of the circuit.

I solved the question as follows ;

VB = [24K / 24K+82K] x 16V = 3,62 Volt

RB = 24Kx82K / 24k+82k = 18,56K

6 = 16 - ICx5,6k

Ic = 1,78mA

IC = ßxIb = 150xIb

Ib = 11,86 microamper

IE = 11,86x10^-6 x 151 = 1,79mA

re = 26mV / 1,79mA = 14,5

VB - VBE - IBxRB - IExRE = 0

3,62 - 0,7 - [ (11,86 x 10^6) x 18,56K ] - 1,79mA x RE = 0

RE = 402K

Av = -ß x Rc / ßre + (ß+1)RE

Av = -150 x 5600 / 2,175 + 0 (The reason why it is 0 is because the Re resistor and capacitor are in parallel, I know that it is an ineffective element in AC analysis.)

This is my solution, are my solution steps correct? or if there is a point where I made a mistake when converting units, can you warn me, I need to correct my shortcomings and learn the right one. thanks a lot in advance