#Transistor emitter collector base free#

That's because the piece containing naturally faster electrons will enforce those electrons to the other piece, making it become more negative. Whenever two conducting objects made out of different matters touch each other there will allways appear a voltage difference between the two. Maybe you wonder why you do not measure 0.7 Volt when applying a voltmeter between base wire and emitter wire. Other electrons will then again be repelled. That way the electric field increases back to 0.7 Volt.

They would recombinate with those holes, and, thus blockaded there, would make that zone become more negative again. Should the field intensity decrease, electrons would be able to enter the zone containing holes. Then, again because of the field, it turns back and accelerates back towards the collector or emitter.

It's speed decreases gradually and it stops just when it was going to enter the zone where the holes are. Those 0.7 Volt are the energy of the fastest electrons of the collector or emitter: when at random one of them speeds towards the base, it is repelled by that electric field of 0.7 Volt inside the empty zone. That voltage repels the electrons of the collector towards the collector, the electrons of the emitter towards the emitter, and the holes of the base towards the inside of the base. When the transistor is not connected to any voltage source, the base has a voltage difference of -0.7 Volt with collector and emitter. Yet now there is another missing link just near. Holes can move: if the link of one of the two atoms with one of his neighbours is broken, that will make one electron be available to build the missing link.

#Transistor emitter collector base free#

(A free electron encountering a hole will fill it, what makes both disapear: the free electron becomes a catched electron, part of the link between two silicon atoms, thus a constitutive part of the cristalic structure of the silicon.) (A hole is a lack of link between two atoms: one of the two atoms has an electron available to build a link, yet therefore two electrons are needed, so there is no link. Those two no-man's-land contain doping atoms that generate holes and electrons, yet holes and electrons have anihilitated each other. There are two zones that do not contain holes nor electrons: between collector and base and between base and emitter.The emitter is strongly doped negatively.The positive doping of the base, between emitter and collector, is not concentrated.The whole text will be about that drawing: Look at this schematic drawing of the inside of a transistor. This text is a short explanation about the internal functioning of a bipolar NPN transistor.