# Transistor

Discussion in 'General Electronics Chat' started by mazzi, Apr 8, 2012.

1. ### mazzi Thread Starter New Member

Dec 29, 2011
3
0
Hello
how can I calculate the drain current for transistor T1 and the base current for transistor T2 in the attached circuit. Given the following data

R1 = 102
R2 = 8
E = 15V
Vin = 12.3V
VBE = 0.6V
hFE = 12
Vt = 3.5V
S = 0.05A/v
Id = ?
Ib = ?

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2. ### panic mode Senior Member

Oct 10, 2011
1,328
305
using circuit analysis methods you have already learned (KVL, KCL, Ohms law, transistor models and modes of operation...)

Ve=Ie*R2 // Ohms Law
Vb=VBE+Ve // KVL
Id=Is=Ib+ Vb/R1 // KCL
Ie=(hFE+1)*Ib // BJT
etc.

3. ### Audioguru New Member

Dec 20, 2007
9,411
896
What is the value of R1? 102 ohms or 1k ohms? Sometimes a 1k Oriental resistor is marked 102.

Why did you list the Vt threshold voltage for the Mosfet which is when its current is only 0.25mA and it is almost turned off? Instead we need to know the gate-source voltage when it is turned on which might be 10V. Then the input needs to be +25V for the output to be at about +14V.