Friday, 10 June 2011

Power supplies, AC or DC?

I mentioned a problem with the power supply last week, and ever since then Frank has been pontificating on the various methods of electrical generation. According to Frank, there are seven different ways to do it. The problem is, the only one that's practical creates AC power, but we really need DC.

The typical method of creating electrical power involves moving a conductor through a magnetic field, called electromagnetic induction. That's how we get all our power for household use.

The other methods all make DC power and involve converting other forms of energy to electrical. Physically pulling electrons from atoms creates static electricity (like a Van de Graaff generator). Using chemicals is called electrochemistry (as in a battery). When light is changed to electricity it's known as photoelectric power (think solar power). Using heat is thermoelectric (used in electronic thermometers). Putting certain solids under stress is makes piezoelectric power (used in a scale). But the best one of all uses a radioactive source to produce loose electrons: betavoltaic power (but promethium can produce x-rays!)

The big problem is that all the DC power generators create such low voltages or currents that they aren't practical. We're still working on it.

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