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TRANSISTOR

- Is an electronic device made of three layers of semiconductor material that can act an insulator and a conductor.TransistorThe word transistor is a combination of the terms transconductance and variable resistor

Transistor are commonly used in Amplification, switching, and buffering signals or applied voltages.

Lee De Forest- an American inventor and physicist , made the vacuum tube triode or audion as he called it.

History of Transistor

Before transistors were invented, circuits used vacuum tubes:Fragile, large in size, heavy, generate large quantities of heat, require a large amount of power

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The First Transistor The first transistors were created at Bell Telephone Laboratories in 1947

William Shockley, John Bardeen, and Walter Brattain created the transistors in and effort to develop a technology that would overcome the problems of tubes

The first patents for the principle of a field effect transistor were registered in 1928 by Julius Lillenfield. Shockley, Bardeen, and Brattain had referenced this material in their work

Today an advanced microprossesor can have as many as 1.7 billion transistors.

Two Types of Transistors

NPNPNPWhere the majority current carriers are electrons The majority current in the Pnp transistor are holesCollector- is the larger electrical supply .Base- is a gate controller device for the larger electrical supply.Emitter- is the outlet for that supply.

In the npn transistor, a p-type element is sandwiched between n-type elements.

the n-type emitter material sends negative electrons to the collector.

The pnp transistor has an n-type semiconductor in intimate contact with a p-type element on both sides.

The p-type emitter material sends positive holes to the collector.

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