A transistor is a semiconductor that is used to amplify an input. A transistor can take a small input signal and control a much larger one. There are various types of transistors. MOSFETS, BJT to name a few. The transistor that we are mainly concerned about for the purpose of building our first robot is a BJT (Bipolar Junction Transistor). There are mainly two types of BJT: n-p-n and p-n-p. BJT transistors have three connections: emitter, base and collector. The base is where the input signal is fed. In an n-p-n transistor the base has to be "more" positive than the emitter for the current to flow from the collector to emitter.Here, the collector has to be more positive than the emitter. In a p-n-p transistor, the emitter has to be more positive than the collector and the base has to be "more" negative than the emitter.
In the next post we will discuss about the applications of transistors. In case you missed
the previous posts in this series, go here.