Thanks again Silverpixeli! But alas i have more questions again. This time about voltage amplifiers. I went over it in class today and we watched a few videos and i even watched the VTextbook video on it just then, but I'm still confused.
Firstly, i don't really understand how a transistor works in a circuit. From what i understood, it has a voltage input that goes through the collector and then one that comes through the base? If that's correct, are they actually 2 different power sources or do they come from the same power supply. If so, then how do you regulate how much voltage goes through it from the base input? From a picture i saw in class today, the base is apparently usually connected to a capacitor? I don't really know what a capacitor is either, but doesn't that store energy/voltage? Is that connected back to the same power supply of the circuit if that's the case. How do you regulate how much voltage goes through that anyway?
Next, from what i gathered, when no input voltage comes through the base, the resistance is infinite since it is basically 2 diodes facing each other and one of them will be in reverse bias? When there is a voltage input from the base that goes above the switch on voltage it will work and the resistance will basically be 0. How does the 'switch on voltage' allow the diode to work if it is approaching it in reverse bias? You would need like 50V to break it but it is still only about 0.7 V according to my book.
Even if that all makes sense to me, i still don't really know what it does. It amplifies the voltage but how? Is it because you are basically adding 2 voltages from 2 power sources together. Almost like as if you were adding ordinates of 2 sine graphs? I hardly understand what all the graphs are about either, but if someone can enlighten me on how all the above works, maybe i will be able to figure it out for myself.
Thanks
Transistor workings are also not really part of the course. Capacitors, also, are left for the detailed study 'further electronics'.
Voltage amplification questions range from interpreting graphs, talking about cutoff/saturation, voltage gain and converting from input signals to output signals and back.
A transistor definitely has the two source things going on, but I'm not sure what you're talking about when you mention two diodes and one in reverse bias mode.
Whatever voltage applies at the base is like the voltage across a diode, in that if it's lower than some switch on value, there will be no conduction. A transistor is different in that when the diode IS switched on, the majority of the current to the emitter doesn't come through the base, it comes through the collector. Basically, the voltage across the base regulates how much current can come through the collector. Typically, you have the collector hooked up to some more powerful supply that can provide as much current to the collector as the transistor will allow through it.
This is useful for signal amplification as follows: Typically you have a signal captured as small variations in voltage/current in a circuit. If you feed this varying voltage into the base of a transistor, it will allow proportionate amounts of current through from the high-power collector. The result will be a higher power version of your original signal coming out of the emitter!
This assumes that your input signal is always within the working range of the transistor. Too low, and you won't open the gate for current from the collector. We refer to this as 'cutoff'. Too high, and you wont be able to get any more current through the transistor, and all higher signals will output that same max. We call this saturation. Both are examples of 'clipping' which result in the extremes of a signal being 'chopped off' from signals that dont lie within this range.
The complicated circuits that actually make this work are not studied and I have no understanding of them personally other than the high-level sketch above. Sorry
As for the amplifier graphs, Vin - Vout graphs map input voltages to output voltages. If you put in an input signal (often represented as a Vin - time graph) you can use the amplifier's characteristic graph to map it to an output signal v. time graph. This process, and the reverse, are semi-common exam questions.