How can I convert a PNP to NPN transistor?
If you have the exact NPN equivalent you only need to mount the circuit as it is drawn, so that the base, collector and emitter terminals of the NPN are connected where base, collector and emitter of the PNP should go, and then reverse the power supply polarity. This trick works in most cases, but it depends on the circuit we are speaking about. The exact same thing works if you want to use a PNP instead of a NPN. Remember that all the transistors in the circuit should be changed with theyr complementary, so if you have PNP's and NPN's in your circuit there's no way out, you need both types of transistors.