I keep seeing a not-transistor outlined like this:
(source: waitingforfriday.com)
But every picture of an actual transistor looks like this:
(source: nefarius.at)
I can't help but notice four lines exiting the diagram, but only three legs exiting the physical transistor. The same seems to be the case for all the transistors I've looked at. What's the missing leg?
Best Answer
You mis-identified what a transistor is.
The transistor is one component in that circuit that you referenced. The symbol for an NPN transistor is:
Look closely and you will see one of these in there.
Each of the "squiggly" components is a resistor. You posted a circuit consisting of 2 resistors and 1 transistor.