> I built a simple voltage multiplier as suggested out of two diodes and two > capacitors and plugged in a 12VAC as input. I got out around 36 volts DC > based on the caps I used (I am assuming that is the reason it was not closer > to 24volts.
It's not your cap choice, it's how these doublers and multipliers work. With little or no load, they charge to the peak input voltage. Since AC varies, spending part of its time at low voltages, to deliver the same power* as a DC voltage, it also has to spend part of its time at higher than the equivalent DC voltage. So 12VAC is generally really 12VAC RMS, delivered as a sine wave. The peak voltage of a sine wave is 1.41 (the square root of 2) times the RMS voltage, or about 17 volts. The peak to peak (negative peak to positive peak) is twice this, or about 34 volts - which is what you'd expect from a doubler supply like yours. I hope I've shed more light than confusion on the issue! - John * into a resistive load - it gets more fun when reactance comes into play -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
