Cheap Capacitors

Ready for a ridiculous over-simplification of what a capacitor is and does?

Think of your city’s municipal water tower. You have water being pumped into the top, a reservoir to hold a bunch of water, and a pipe coming out the bottom which ties into the water distribution network (“pipes”). Why have the water tower at all? Why not just hook the pump into the pipes and bypass the tower completely? Two reasons (again, over-simplifying here):

1. The need for water into the pipes fluctuates with usage.
2. The inflow of water into the pump fluctuates.

The water tower essentially is a large buffer. You put water into it and you can be relatively certain the water coming out the bottom is at the same pressure and the same volume. (Yeah, I know, it’ll fluctuate — keeping it simple.) If the pressure were to spike it could blow out the pipes. If the water were to run out, the taps would run dry.

Think of a capacitor as water tower for electricity. Dirty power goes in one side, clean and regulated power comes out the other. Sensitive electronic components need this clean power.

But what would happen if your city needed a water tower of a specific size, but the contractor cheated and instead put a cheap metal shell around a much smaller tower to save some money? Eventually the city would go dry, right?

This picture illustrates how some unscrupulous distributor cut corners to offer a larger capacitor for the price of a smaller one. This will eventually destroy any sensitive electronics down-stream. Thieves.