PNP transistors and n-channel transistors function similarly to “signal turns switch on” relays and tubes; likewise NPN transistors and p-channel transistors function similarly to “signal ...

Buzzer Basics: Technologies, Drive Circuits, and Live Sound Demos The positive temperature-coefficient (PTC) thermistor in the pnp transistor’s current-control circuit prevents short-circuit damage.

By using dual bipolar devices in one case, the manufacturer nearly perfectly matches the two devices. Although this Design Idea describes a positive power supply, you can realize a similar ...