Isolation Transformer - Use One!

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  • SteveNielsen
    Retired Tech
    • Jun 2012
    • 2327
    • USA

    #21
    Re: Isolation Transformer - Use One!

    Originally posted by budm
    I used to have one, same principle as used the UPS with AVR. The relay clicking is very annoying when input live Voltage varies a lot.
    Example of more complicated one (not using auto-transformer) than the one in yours, but same idea.

    Lots of newer regulators us TRAIAC instead of relays.
    Interesting info. I can understand how the clicking gets annoying. It doesn't bother me much, just another noise in the house and at least I know what it is.

    I would like to find a schematic for this one so I can see how it is switching between output voltages. I think I'll start another thread about it over in power supplies forum and not hijack this one.
    Last edited by SteveNielsen; 11-01-2015, 08:05 AM.

    Comment

    • Per Hansson
      Super Moderator
      • Jul 2005
      • 5895
      • Sweden

      #22
      Re: Isolation Transformer - Use One!

      Might be something similar to this:

      https://www.badcaps.net/forum/showth...715#post473715

      EDIT: OMG 3000:th post in only 10 years, my oh my!
      Last edited by Per Hansson; 11-01-2015, 08:23 AM.
      "The one who says it cannot be done should never interrupt the one who is doing it."

      Comment

      • fzabkar
        Badcaps Veteran
        • Mar 2009
        • 772
        • Australia

        #23
        Re: Isolation Transformer - Use One!

        Originally posted by budm
        Example of more complicated one (not using auto-transformer) than the one in yours, but same idea.
        The block diagram shows an auto-transformer for switching between taps, and a "stepped down transformer" for generating the DC supplies for the electronics.

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #24
          Re: Isolation Transformer - Use One!

          But the same concept, you use the Autotransformer to do the boost or buck buy switching the taps, and the electronics to drive the relays based on AC input Voltage. page 22, 26, shows the basic AVR, table 3 shows stabilized 214VAC output with input capture range of 150VAC ~248vac.
          Tap switching AC regulator has been around for decades. You can also use motor drive Variac, MONSTER power uses that in one of its home unit.
          Last edited by budm; 11-01-2015, 04:41 PM.
          Never stop learning
          Basic LCD TV and Monitor troubleshooting guides.
          http://www.badcaps.net/forum/showthr...956#post305956

          Voltage Regulator (LDO) testing:
          http://www.badcaps.net/forum/showthr...999#post300999

          Inverter testing using old CFL:
          http://www.badcaps.net/forum/showthr...er+testing+cfl

          Tear down pictures : Hit the ">" Show Albums and stories" on the left side
          http://s807.photobucket.com/user/budm/library/

          TV Factory reset codes listing:
          http://www.badcaps.net/forum/showthread.php?t=24809

          Comment

          • fzabkar
            Badcaps Veteran
            • Mar 2009
            • 772
            • Australia

            #25
            Re: Isolation Transformer - Use One!

            The first tap-switching AVR I encountered was a Topaz unit in 1981. I was supposed to stabilise the supply for a minicomputer, but it was a useless buzz-box that just made things worse.

            Comment

            • SteveNielsen
              Retired Tech
              • Jun 2012
              • 2327
              • USA

              #26
              Re: Isolation Transformer - Use One!

              You guys are right. I finally sussed it out. It is an autotransformer with a center-tapped tertiary winding to supply power to the electronics and relay coils.

              Comment

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