Voltage Doubler DC performance?

Discussion in 'General Electronics Chat' started by tmiuser, Mar 17, 2011.

  1. tmiuser

    Thread Starter New Member

    Dec 22, 2010
    I know that a voltage doubler (the old Capacitor/diode circuit) does a good job of multiplying. My question is probably simple......

    If you feed the input of the Voltage Doubler with pure DC....
    (instead of AC.....)
    I am fairly certain you would have a 'zero' output.
    The Capacitor would simply block the DC.

    The reason I am making this question....is that I have a 20 VAC power supply that can be 'switched' to provide only 15VDC. i.e....it can supply either AC or DC. (but not both.....)

    So...I would like to build something that would be able to tell the difference of what the supply is switched to.............

    The first circuit that came to mind was.....The ol' Voltage Doubler.
    What do you Electronic Gurus think? good way to detect the difference???

    : P

  2. Adjuster

    Late Member

    Dec 26, 2010
    A capacitor input voltage doubler might work. Provided that you applied a light load to its output, with a DC input it would give you 0V output after a possible initial charging kick. With 20V RMS sine wave AC, it would give about 55V DC.

    What will be connected to the output of your voltage doubler - some kind of meter?
  3. billbehen

    Active Member

    May 10, 2006
    sounds pretty good. anytime its AC vs DC think capacitor
  4. tom66

    Senior Member

    May 9, 2009
    You could use a diode in reverse. With AC this would conduct every half cycle, and a capacitor could be used to smooth it out (e.g. for a meter.) With DC, no current will flow and the reading will be 0V, provided the cap discharges (you may need a resistor across it to ensure this.)
  5. tmiuser

    Thread Starter New Member

    Dec 22, 2010
    Wow, guys.....good input.
    to answer a question: I will probably connect it to a ADC unit, and feed a micro with it.
    (or...use the ADC on the micro......)
    I like the SIMPLE suggestions.
    So...really..I guess I was thinking along the correct line.

    I love this place.
    : P