It would seen that most circuits use NPN transistors rather than PNP. I understand the difference between the function of the two, and also the manufactering of the two.
But why are PNP transistors the ugly step sister?!?!?
can someone tell me what the main benefits and uses are for each type (pnp/npn - before someone tries to list every transistor ever made )
You're probably missing the point?, it's down to manufacturing processes.
Originally PNP transistors were the most common, back in the germanium days, as they were easier and cheaper to manufacture - when silicon took over it switched, because it was easier and cheaper to make NPN ones in silicon.
so are there any specific reasons apart from cost where you would use one rather than the other. is there anything that a npn can do that cant be achieved with a pnp or vice versa?
It also has to do with majority carrier mobility. The majority carrier in NPN is the electron, while in PNP it is the hole. Electron mobility is considerably higher than that of holes, meaning that NPNs can have higher speed than PNPs.
so are there any specific reasons apart from cost where you would use one rather than the other. is there anything that a npn can do that cant be achieved with a pnp or vice versa?
You can ony use a PNP to source a device if the base voltage is >= the collector voltage. If it is not you need to use a totem pole setup (2 transistors) which is more expensive.
You can ony use a PNP to source a device if the base voltage is >= the collector voltage. If it is not you need to use a totem pole setup (2 transistors) which is more expensive.
Emitter to chassis (+ve), base to switching signal (via a resistor), collector via load to -ve supply. Apply -ve voltage to base, transistor switches ON, and current sinks through the transistor to chassis.
Exactly as you would an NPN, just with the supply reversed.
Emitter to chassis (+ve), base to switching signal (via a resistor), collector via load to -ve supply. Apply -ve voltage to base, transistor switches ON, and current sinks through the transistor to chassis.
Exactly as you would an NPN, just with the supply reversed.
Why are you concerned about conventional current flow?, electron current flow is just as valid - like I said earlier, don't get stuck in the 'HT rails must be positive of chassis' syndrome. A negative HT rail and sinking electron current flow is no different.
Why are you concerned about conventional current flow?, electron current flow is just as valid - like I said earlier, don't get stuck in the 'HT rails must be positive of chassis' syndrome. A negative HT rail and sinking electron current flow is no different.
I'm not concerned about conventional flow. I just wanted to be sure we were on the same page. And I still want to see a schematic of how you expect to get a PNP common emitter stage to sink current.