Transistors  The Transistor was invented in 1948 and  The New York Herald Tribune announced the invention of the transistor as the … “Electronic device that will change our very life's existence".  The reason for this life changing label is because these small components are only controlled by other small components. This is known as micro - electronics.

 Three scientist John Bardeen, Walter Brattain and William Shockly at Bell Laboratories in New York City worked with materials such as silicon or germanium to produce crystalline materials (aka chips) that would function as semiconductors.

 Semiconductors are chips that, in their natural state, are solidly insulators, but when salted with impurities such as boron or phosphorus they become excellent conductors.  By using semiconductor chips, scientists could duplicate electronics processes that the vacuum tubes were doing yet without warm-up time, less cost, less, power, faster, smaller, longer life, and less weight.

 Also a Semiconductive transistor is able to work as anyone of three fundamental processes. A switch, it could amplify current, and able to convert DC and AC.  The first Transistor emerged on the market as a bipolar transistor. It worked with the idea of junction voids and bridges. Lets look at this concept.

 Remember, that a Semiconductors can be formed to have a negative charge and allow current to flow by electrons or can be formed to have a positive charge and allow current to flow by solid-state holes. These are known as N-type or P-type materials.

 Transistors are basically a configuration of two solid-state diodes back to back and combines three layers of N-type and P- Type materials alternately so they form both types of transistors; negative, positive, negative (NPN) negative, positive, negative (NPN) positive, negative, positive. (PNP)

 NPN and PNP transistor configurations work just the same except that they allow current to flow in opposite directions.  The term that defines the polarity connection of the transistor is bias. If it is connected in forward-bias then the component will function correctly, if in reverse-bias the transistor will restrict current flow.

 In order to define the bias of a transistor you must know the names of the leads. There are three: base, emitter, and collector

 When a N-type chip and a P-type chip come in contact with each other a junction is created and depending on the bias of the transistor the junction can either be a bridge or a void.

 The base is a very thin center layer (only about.001 inches thick) of material and is the saturation region were electrons or holes are fed into the transistor to allow it to pass current.  The emitter is the sending lead that (if in forward-bias) will receive current from the battery and send it through the base region then onto the receiving lead, the collector.

 Only 5% of the current flowing in a transistor is through E/B junction, the other 95% flows through the E/C junction. So when a slight change occurs in the E/B a larger change occurs in the EC.  If the transistor is in reverse-bias a void is induced around one of the junctions and cause current to slow or stop.

 The process of controlling a large current by a small current is called amplification.

 Transistors are packaged in several styles of casings and it is necessary to always verify which lead is which because they are not always in the same location on all casing styles.  And finally, the rating of a transistor tells us how many times the E/C current will be higher than the E/B current.