PNP Transistor - Amateur Question

[carlodelmundo]

I understand that when we apply voltage to the Base of the PNP Transistor (Emitter, Base, Collector), we actually block current from passing from Emitter to Current.

If there is no voltage applied to base, then current flows freely.

If this is the case... how come when I wire the following:

1.) + terminal of battery to
2.) diode (pointing towards +) to
3.) "Emitter" of PNP Transistor
4.) The "collector" of PNP transistor goes to
5.) - terminal of battery.

I get no closed circuit? (by the way, there's a resistor and LED between 4 and 5). However, when a voltage is applied to the base (even the slightest), the current is open?

 

[vk6kro]

The missing component is the base resistor.
Even though this is connected to ground, it supplies current to the base of the transistor to turn on the collector-emitter current.

PNP transistors are exactly the same as NPN transistors, except that the polaraity is reversed.

So, if it helps, just rotate the circuit so that the collector is at the top. You can now see the importance of having a base resistor and where it has to go.

 

[waht]

Yes, basically in pnp transistors, you have to let current out of the base to turn on the transistor. This occurs when the base voltage is lower than the emitter voltage.