Transistor design done, just have a problem

Thread Starter

Tahmod

Joined Feb 23, 2013
12
I have built this circuit, but the problem is that I dont know how to find the emitter and collector resistor to provide me a 250mA.

This is found from the circuit by measuring:
Rc=24ohms

These are my Start value taken from the datasheet:
Vce=1.2
Ic=0.3A
Ib=1.5mA
Hfe=200


KVL load:
Vcc-vc-Vce-Ve=0
Vcc-Vce=IcRc+IeRe
Vcc-Vce=IbBRc+IbBRe
(Vcc-Vce)/IbB=Rc+Re
(6-1.2)/(1.5*10^-3 *200)=24 + Re
16ohms=24ohms+Re
16-24=Re
-8=Re


1.-I got a negative resistance what is wrong with this resistor? :)2..
2.-Maybe is the data, I took from datasheet is wrong?
 
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