Transistor.

THEORY:

http://upload.wikimedia.org/wikipedia/commons/

Transistors have been around since the 1920's, the difference is the material that its used. Just like back in the days, a transistor is used by taking a low amount of ampere to turn on (amplify) a high amount of ampere. Transistors come in 2 types NPN and PNP. One is base negatively on and other base positively. This is a three wire transistor that have a base, collector and emitter. The base is were a low amount of current travels from which then goes through to the emitter. When there's enough current flowing from the base to the emitter, it then opens the gate for the collector to join the base which then allows the high current to join with the low and pass through the emitter. This shows that low ampere is used to switch on high ampere. Transistors are a semiconductor like a diode and NPN or PNP   means N= free electrons P= holes N= free electrons. This shows how current/voltage would through a transistor which is just like a diode hence they say its 2 diode back to back. 

TEST:

http://curiosity.discovery.com/topic/computer-parts/electronics-parts-pictures1.htm

When determining which terminal is base, collector and emitter, a multimeter can be used with it on the diode test function. The base is the common to both collector and emitter. The collector will have a lower voltage running through than the emitter. When transistor is fully off, this is known as cut off region and when it fully on, this is known as the saturated region and when in between its known as active region. When in the active region, a high voltage drop will occur and if too high of a voltage drop it could cause heat, which can  build up and end up with the transistor burning out and may melt due to the heat. In the cut off region, there is no voltage/current through the base of the transistor at all therefore transistor is not operating. The saturated region is when the transistor is fully on and working and voltage drop is minimum.



REFLECTION:

Transistors have come along way from the 1920's. Modern man would not have had allot today like cellphones, computers if it werent for for the few men that produced the transistor. These components are important due to vehicles needing more than just 12v for some of its components. Like the old sayin goes big thing come in small packages.