![]() Transistor was invented in 1947 by three American physicists, John Bardeen, Walter H. This current controls the movement of electrons within the transistor. As electrons move through the device, they create a current that flows from the base to the emitter. ![]() What is a transistor?Ī transistor consists of three basic parts: a collector, base, and emitter. The smaller the gap between the plates, the faster the circuit can operate. They consist of two metal plates separated by a thin insulator. Transistors are the building blocks of modern electronics. They allow computers to store data and perform calculations at lightning speed. Let's explore the output characteristics of an NPN transistor we were already seen how we can make our NPN transistor to work as an amplifier and we've seen these different currents and everything if your emitter base has to be forward biased and the collector base has to be reverse biased and we also put the names for these voltages this voltage which is connected to the base with respect to the emitter we call it as the vbe and we call this as VCE in a previous video we saw how changing vbe how changing this voltage affects this current we call it as the input characteristics so in the output characteristics what we can do is we're going to change this voltage this is the output voltage and we'll see how this affects the output current IC so let's do that so we're going to plot a graph of IC IC versus VCE and one thing we need to be careful about is remember that IC can also change due to IB that's the whole idea behind amplification right when I will be doubles IC also doubles if IB were to triple IC would also triple but we don't want our IC to change with IB we want to see how IC behaves when VCE changes so we don't want I be to metal to changes in IB to metal with our experiment and for that reason when we perform this experiment we have to make sure that IB is a constant so IB must be constant alright let's look at the plot now so here it is what would you think this graph looks like well what is this is a graph where the PN Junction so here's the PM is the n where the PN Junction is reverse biased right because the then the n-type is going to more positive than the p-type so this should be a graph of the reverse bias and we've seen what the real grass graph looks like in that the current is usually independent of the voltage and the same thing when I find over here the current that we get over here is pretty much independent of this voltage and the reason for that is because this current only depends on how many electrons get injected over here for example if hundred electrons get injected one electron gets collected or one electron comes out of the base then regardless of what voltage you what ninety-nine will get swept across over here so if you were to see this graph you much pretty much see a constant value so this is what you would see here it is voila there it is this is the part that I was saying that this is a constant value and this may be for a particular value of IB I don't know maybe that is for so let's say that the IB for this entire experiment was fixed at 10 micro amperes as an example and so you can see that IC value is pretty much fixed alright and this IC value oh it's it's it's amplified compared to IB maybe in this transistor it is hundred times more amplified so then this IC value would be about hundred times more than ten micro amperes and a hundred times more than ten would be about 1 milliampere oops so it's that so this value let's say is about 1 milliampere that's why I see is in milli amperes now you may be wondering what's going on over here well what is over here even with the current being input current being 10 micro ampere here the the output current is changing over here so this is the part where the output current is is changing with respect to the output voltage can you see that this is the part so why is that happening well the thing is as you decrease the output voltage says you go from plus Phi 2 plus 4 and then plus 3 then maybe plus 2 in plus 1 and so on we're still fine nothing happens but once you decrease the voltage below 0.7 volt let me just write that down so let's say this vc value went below point 7 volt I don't know maybe maybe it goes to point 3 world point 3 would now notice that even though the collector is connected to a positive supply the base is now more positive than the collector because base is at 0.Transistors are tiny electronic components that control the flow of electricity within microchips.
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