# logic circut bu BJT

Discussion in 'Homework Help' started by eng.mustafasalah, Mar 3, 2013.

1. ### eng.mustafasalah Thread Starter Member

Nov 10, 2011
41
2
http://im34.gulfup.com/CzXfF.jpg

q4 - in the circuit shown what is the minimum RL that the invert can drive with out causing the output drop blew 4 V when Vi = 0V ?

i don't understand what he want in Q4

how i solve question 4 ?

Last edited: Mar 3, 2013
2. ### Brownout Well-Known Member

Jan 10, 2012
2,364
1,000
I don't understand it either. In fact, I can't even read it.

3. ### eng.mustafasalah Thread Starter Member

Nov 10, 2011
41
2
i write the q4 ...
q4 - in the circuit shown what is the minimum RL that the invert can drive with out causing the output drop blew 4 V when Vi = 0V ?

4. ### Brownout Well-Known Member

Jan 10, 2012
2,364
1,000
OH, he wants you to provide the minumum resistance for RL which the inverter can drive without causing the output to drop below 4V when Vi=0. Vi is the input voltage to the inverter.

5. ### eng.mustafasalah Thread Starter Member

Nov 10, 2011
41
2
ok
how i prove that ? do you know ?

6. ### Brownout Well-Known Member

Jan 10, 2012
2,364
1,000
Well, when the input voltage = 0V, is the transistor on or off? If it's on, then you need to derive an expression for output voltage with the transistor on. If it's off, then you need to derive an expression for the output voltage with the transistor off.

7. ### eng.mustafasalah Thread Starter Member

Nov 10, 2011
41
2
thank uuuuuuuuuuuuuuuuuuuuuuuuuu