Chapter · Electricity
Capacitors
Two plates and a gap nothing crosses. It blocks a steady voltage, passes a changing one, and every board you own has a dozen of them holding the rail up.
- 09What a capacitor is6 minTwo pieces of metal facing each other with a gap between them. Read as a circuit that is a break, and yet current runs in both wires the moment you connect it — which is the whole part, and the reason a board has a dozen of them on it.
- 10Inside a capacitor7 minA 100 nF ceramic is smaller than a grain of rice and a 100 µF electrolytic is the size of a thumb. Both are two plates and a gap — the difference is what is in the gap, and it is the reason one of them explodes if you fit it backwards.
- 11Charging through a resistor7 minA capacitor on its own has no speed — it charges as fast as the wire allows. Put a resistor in front of it and it gets one, and that number is the only piece of capacitor arithmetic you will use again.
- 12Decoupling capacitors9 minEvery schematic has small capacitors scattered next to the chips and no explanation of what they do. They are there for the two milliseconds after something switches on — the ones your regulator sleeps through and your board reboots in.
- 13Bypass caps and lead length7 minA schematic carries 1 µF, 100 nF and 1 nF side by side, and a capacitor with its legs left long is worth a fraction of the same part cropped short. Both of those are the same fact — the wires to a capacitor are part of the capacitor.
Start at 09 and read down — the order is the order things get easier in. Or take the one with your part in it; every article stands on its own, and links back to whatever it needs.