Problem on Transistor circuits

[Velec741]

hi there...
have any idea on how to solve this one?
View attachment 60302

 

[ericgibbs]

hi there...
have any idea on how to solve this one?
View attachment 60302

hi,
Give you a few hints.

Its a current mirror, that means the same current flows thru both resistors, the left side transistor is connected collector to base which makes it a diode.

What do you think the answer is and why.?

 

[Velec741]

is it 27.8V?

Ir=(12-0.7)/10k = 1.13mA ........ (1)

Ir=Ic+IB1+IB2 ;
Ir=Ic+(2*Ic/Bo)------------->(beta)
Ir=Ic(1+2/Bo)

from (1),
1.13=Ic(1+2/100)
=> Ic=1.107mA

Ic of trans1 = Ic of Trans2 =Ic' =(50-V2)/20k = 1.107
=> V2=27.86V

that ok?

 

[ericgibbs]

is it 27.8V?

Ir=(12-0.7)/10k = 1.13mA ........ (1)

Ir=Ic+IB1+IB2 ;
Ir=Ic+(2*Ic/Bo)------------->(beta)
Ir=Ic(1+2/Bo)

from (1),
1.13=Ic(1+2/100)
=> Ic=1.107mA

Ic of trans1 = Ic of Trans2 =Ic' =(50-V2)/20k = 1.107
=> V2=27.86V

that ok?

hi,
That looks fine to me.

Well done.

 

[Velec741]

thanks ericgibbs...
learnt something new