Hi!

can anyone help me about this DTL circuit in the photo below?

thiis circuit is about finding the minimum HFE value

Fan-out is = 20 and the other values are in the photo below,there's missing one Rc value and it's the same Rc=1k

The hfe has to be about 11, hfe=11, but...
i solved it and I get hfe =7

what's the problem????

please HELP!





http://g.imageshack.us/thpix.php

 

What assumption are you making about the thresholds for a logic 1 and a logic 0. You need to take into account the beta of the transistor, the base resistance and the collector resistance none of which you have provided.

 

Look at the attached schematic.

EDIT: Hmmm, I probably should have just given some hints. I forgot this was a homework problem.

 

thank you very much Ron!!!!