Need to switch something on or off using a microcontroller? Using a transistor is one of the best ways to do this, but how exactly do you design properly for transistor switching? [Ben Krasnow] put together a tutorial in which he does an excellent job of explaining the ins and outs of designing transistor control circuits.
We’ve embedded his twenty-minute video after the break. In it he talks about the use of transistors, the difference between NPN and PNP transistors, and the design specifics you need to know when working with them. We think that beginners will find [Ben's] demonstration of how to calculates Hfe, which is the base current necessary to fully switch the transistor. If this is gibberish to you, have no fear. [Ben's] instruction is clear and easily understandable.
The one thing we missed in the video is clarification about base current protection for PNP transistors. [Ben] mentions that there’s no easy circuitry that can be used on the base of a PNP to regulate flow from the emitter to the base, but he doesn’t elaborate. Otherwise, it’s everything we could have wanted on the topic.