I spent over nine hours doing variations on this today. Rather, I spent 3 hours physically turning AC power into DC, and the six hours prior to that, I was simulating the process on PSpice, trying to get the results that my professor's pre-lab assignment asked for, only to find out that they were impossible to get, and she set it up that way in some crude attempt to prevent people from cheating.

This is basically what you have to do:

       _______    ________    _________    ______
  -----|     |----|      |----|       |----|    |
  |    |rect-| +  |      | +  |voltage| +  |    |
 VAC   |ifier| V1 |Filter| V2 |regu-  | VL |Load|
  |    |     | -  |      | -  |lator  | -  |    |

VAC is your standard sinusoidal voltage source. A sin (ωt), if you like. You can get one from a wall socket, or by playing a sine wave on your favorite synthesizer after cutting a mono patch cord in half and plugging it into the output. V1 is almost the same waveform as VAC, but with the negative half "chopped off", or scaled by -1. V2 is a sawtooth wave, with peaks equal to those of V1. VL is 100% pure DC (usually, almost).

If you want to do this the quickest and dirtiest way, use:

Here are the components I used today:
  • rectifier diode: 1N4007
  • capacitor: 150uF, 50V (watch the polarity!)
  • resistor1: 1.3kΩ
  • zener diode: 1N5425B
  • load resistor: 2.4kΩ
Thus did I successfully convert 19.5Vrms AC power at 60Hz into 14.96VDC.
Diode spec sheets for those listed above can be found at www.fairchildsemi.com.

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