How do you convert npn signal to pnp signal?

To convert an NPN signal to a PNP signal, you can use an inverter circuit, typically implemented with a transistor or a logic gate. For a simple transistor-based solution, connect the NPN transistor's collector to the power supply, its emitter to the load, and the base to the NPN signal through a resistor. When the NPN is on (high signal), it will turn off the PNP transistor, resulting in a low output, and vice versa, effectively inverting the signal.