Transistor (transistor being a semiconductor capable of amplification) designed like a sandwich with semiconducting material on either side of a “base” semiconductor in the middle (the semiconducting material used for the base is different from that used for the “sandwich bread” one being p type and one being n type); bipolar transistors are commonly found in high-end amplifiers. The two semiconducting materials on either side of the base are known as the emitter and collector. As a small signal input is placed on the base to emitter relationship (a small amount of current is applied – the input signal coming into the amplifier), either free electrons or holes are transferred from the emitter to the base (the type of semiconducting material determines if so-called holes or free electrons are transferred). There is an attraction relationship between the base and the collector, which allows most of the free electrons or holes released by the emitter into the base to flow from the base into the collector. This transference creates amplification as a small signal sets the process in motion resulting in larger movement of energy. hink of this process in terms of three office buildings standing in a row, the middle office building is brick and is red and the outer two office buildings are made of glass and are blue. As a person enters the middle office building, this person is the input signal. That person moves from the middle brick office building to the glass building on the left, the emitter building. The job of the emitter building is to send people out so as the one person comes in, the building manager sends twenty people over to the brick building. The glass building on the right, the collector building, has the job of collecting free people from the brick building, the base building. So the collector building’s manager allows 18 of the 20 people to move into his glass building, the collector. The overall process between the buildings results in a single person creating the movement of 18 people to the final building, which is the output. Thus an input signal of one person results in an amplified output signal of 18 people.