fuzzybabybunny:
I'm trying to understand transistor amplification here.Uhhh... I don't see how a transistor is "amplifying" anything. If an NPN transistor gets ~0.7V+ across its base the collector and emitter begin to allow current to flow through. The collector and emitter are hooked up to a completely separate power source. For example, it's not taking the 0.7V produced from my 5V USB power supply and amplifying that directly into a 12V power source. How is this amplification?
Its amplification because a small signal controls a large signal with more power.
It's about as much "amplification" as my little Arduino is doing by sending a 5V signal to a relay that "amplifies" a 120V AC circuit connected on the other side, but I don't ever hear people say that a relay is amplifying voltage or current.
But they do, but not as often because amplifying a digital signal is normally called "fanout" or "buffering" or "boosting".
It seems to me that a transistor is merely controlling a greater voltage or current with its own smaller voltage and current. Am I missing something? I can't expect to take a single little 5V 1A power supply and through a transistor turn it into 12V or 5A, right?
There's nothing mere about controlling, that's how nearly all amplifiers work (lasers and masers are the
exception). What's amplified is the power in the signal, we don't care whether that signal shares a
power supply with the input signal, we only care about the actual signal.