# Simple Circuit

1. Sep 14, 2006

### ravenprp

http://img153.imageshack.us/img153/9007/untitledvb8.png

That is my TTL circuit. I forgot to add +5v and a circle at the top of the diagram, so pretend it's there.

Do I have to use the voltage divider equation to get the value of Vout?

(5v)(Rl)/ (Rl + Rc) where Rl = 1kohm, Rc = 100kohm?

2. Sep 17, 2006

### Staff: Mentor

Not exactly. You need to assume some Beta for the transistor, then write the equations for the base and collector currents, assuming some number for the Vbe drop. Remember that the emitter current is Ic + Ib (it's easy to forget that small adjustment and assume that Ie = Ic).

BTW, this is not a TTL circuit. It is an emitter-follower circuit as you have drawn it. The emitter voltage follows the base voltage, minus the Vbe drop.