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Electronics/NPN VS PNP replacment



A blog at the above post seems to indicate that a NPN can be swapped with a PNP by simply using a negative power supply.

So, lets say I have the original NPN circuit with a 9v battery connected with +Vcc at the top of the circuit, and ground at the bottom. Can the NPN be swapped with a PNP and the polarity of the battery switched? Making The bottom of the circuit +VCC and the top GND? Is that really all that needs to be done? - Thanks

Yes, it is possible; at least theoretically.

If you assume a one transistor circuit biased for class A operation and the operating characteristics (beta, biasing voltages, etc.) are similar in each transistor it will work.

In practice, however, it is more likely the circuit will need to be rebiased in order to get the NPN centered up for class A operation.  And, the gain or distortion of the circuit may be little different.

One would probably never want to do such a swap in practice; only for theory of operation, perhaps.

Hope this helps.  


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