Confusion about NPN transistor

[xmen_xwk]

I need to do some switching and I want to turn off both +ve and -ve(GND)

I can use 1 NPN and 1 PNP transistor. But I'm wondering if I can use 2 NPN transistors only, I have some confusion about NPN. I've been reading for long time about transistors and now this is how I can use NPN.



But can I use NPN transistor like below schematic too ?



or only PNP can do this ?

 

[chuckey]

The second circuit is an emitter follower. The load will get the voltage on transistor base minus about .8V and can take beta times the transistors base current. The first circuit, same current in load, but the voltage dropped across it will be Vcc-.2V, the base only needs .8V to make the transistor switch on.
If you change the polarity of Vcc to - and change the symbol, a PNP transistor works just the same.
Frank

 

[treez]

Chuckey is correct. Also, Get on LTspice and try it out on there. To be honest, generally speaking, your top circuit is generally the way to do it...again, "generally" speaking