James Sweet wrote:
Alec S. wrote:
You'll want to read up on basic transistor theory, that should clear
things up a bit. Essentially, bipolar transistors are current-driven,
that is in the case of the NPN type you show you need to have a voltage
on the base which is positive in respect to the emitter with the current
limited by a resistor to turn the transistor on. Often these days
MOSFETs are used instead for applications like this which are voltage
driven and a little simpler to work with. If you look up H-bridge there
should be lots of examples out there you can simply copy, there's even
single IC's which incorporate an entire bridge for you.

Actually, I need more advanced transistor theory, I've already got the
basics: a switching device that controls electric flow. What I need is
more information on the different types, the internals (what's causing
the drain), etc.

I'm aware of all the things you mentioned, but it won't help because I
don't have the money or resources to buy anything. I'm using
components that I'm scavenging off of old electronic equipment.

I'm currently looking around for some MOSFETs that I can salvage.