@peteb2 OH wait I think I see what you are saying. NPN transistors have the arrow pointing out so power flows in on the collector and base and out on the emitter combining power. ie 6v collector 3v base so 9v out on emitter and for PNP arrow pointing in power flows in on Emitter and splits between base and collector like a power divider. ie 9v in on emitter and 6v out on collector and 3v out on base. Is that correct? and I assume that is true for amps as well?
@john-barron Not really the model of what is going on. There are 100s of short sharp explanation videos on YouTube although some will baffle you right down the the very physics & obliterate you with math! When considering the action of what is happening take on the idea that a voltage is a Potential & that electrons flow negative to positive as they are attracted to a positive potential & as each electron leaves what’s known as its covalent bond in orbit around a nucleus of an atom, it therefore makes a ‘hole’. These holes are by interpretation moving in the opposite direction, positive to negative & enter the term Conventional Current for positive to negative hole-flow & electron flow for negative to positive. Here too all this is where we think of voltage as the Potential & it’s what we call the current that is effectively moving. (incidentally Current is what will electrocute you to death, not the voltage & it takes very little current to do so). Power is just a generic term for electricity in this sense although Physics reveals its actual relationship to current & voltage & the resistance in the related circuit.
So to a transistor there’s one way to picture the ‘creature’ as two diode junctions’ for on either PNP or NPN as the base being. As with a standard basic small signal diode there’s a barrier voltage that has to be overcome to enable anything to happen for current to flow which is around 0.6V or 600mV. So think of a transistor as the Base being the junction of two diodes, either the anodes of two diodes or the cathodes of two diodes while their other ends are the Collector or Emitter respectfully. Remember a diode only lets current to flow one direction so equate this idea of the two diodes orientated according to either PNP or NPN transistor. Note that most DMMs will have a Diode Function that enables you to verify the actual devices barrier voltage & is a great way to test the diode junctions of any bipolar junction transistor.
So now in any situation to enable a transistor to do anything useful then a potential is provided across the Collector & Emitter in a polarity depending upon whether its an NPN or PNP and then another applied to the Base. It needs to exceed the device’s barrier of appx 600mV and between the Base & Emitter for a NPN base (polarity depending upon whether it’s a NPN or PNP). This switches on the transistor junction so current flows Collector to Emitter for a NPN & if the voltage on the Base becomes high enough the junction will slip into Saturation which is the max limit of what the junction can do.
Now when it comes to amplification consider if we put a certain low level changing current & therefore voltage onto the base that is also just above the 600mV forward bias barrier voltage then results in the current Collector to Emitter to mimic a copy if you like of the changes on the Base at a far higher magnitude… so we have amplification & we can couple this off the collector with a capacitor that passes the alternating current but none of the DC potential to another stage.
This is a very, very, basic explanation but gives you the concept of what’s happening. There of course are other ways of connecting up a transistor to work within a specific range but that’s a whole lot more interesting & another story… Hope this helps a tiny bit at least. I suggest you have a watch of Paul’s video #13 & even replicate it yourself!