Short Topical Videos
- Horowitz & Hill, The Art of Electronics, 2nd Ed., Ch. 1
Diodes may be the simplest application of semiconductors in electronics. This is getting ahead of ourselves, but they are essentially transistors with the base and collector tied together. In practice, you can think of them as valves that allow current to flow in one direction (the way the arrow points) and not the other. The only penalty is a 0.6V drop across the diode. If the voltage on the upstream side of the diode does not exceed this, current will not flow. If it does, it will. Done!
Yeah, ok. Not done. If you apply a large enough negative voltage, you can overcome a diode, and it will break down and conduct (and maybe burn out) in the wrong direction. Some diodes (e.g. Zener) do this on purpose at a specified voltage. Some diodes can pretty efficiently emit light (LEDs).