Variac 20 amp advice?

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  • wadmancpu
    New Member
    • Dec 2012
    • 8
    • USA

    #1

    Variac 20 amp advice?

    I've been looking online for a 20amp variac and I see Amazon has them for about $100 and Ebay has them for about $70. They all look the same but I'm wondering if there is any real difference between them? They all list brand names that are odd like vevor and others. Any advice would be appreciated. Thanks.
  • sam_sam_sam
    Badcaps Legend
    • Jul 2011
    • 6023
    • USA

    #2
    Re: Variac 20 amp advice?

    No there is no real difference in the ones that have a red outer case
    The voltage meters are crap but you can do a modification to it and have a very good setup the meter that fit it also needs a modification for it be very useful

    If you buy one and you want to do a modification to meter just let me know and will find the post where I did the modification to it and what type of meter that will fit

    When I have some money to spend I going to this same setup on a 5 amp version of to be able to power LED strips to figure out what voltage the strips are ( wish list )
    Attached Files
    Last edited by sam_sam_sam; 06-16-2019, 03:48 PM.

    Comment

    • wadmancpu
      New Member
      • Dec 2012
      • 8
      • USA

      #3
      Re: Variac 20 amp advice?

      Thanks. If you could find the post on that mod that would be great!

      Comment

      • sam_sam_sam
        Badcaps Legend
        • Jul 2011
        • 6023
        • USA

        #4
        Re: Variac 20 amp advice?

        Originally posted by wadmancpu
        Thanks. If you could find the post on that mod that would be great!
        Here is the post where I talk about how I figured out how and where you have to the modifications

        https://www.badcaps.net/forum/showth...to+transformer

        Here is where you can get this meter at

        https://www.ebay.com/itm/Digital-AC1...gAAOxygo9Q5Xoj

        If you decide to get this meter and have in front of you I show you which diode that you have to remove and add a 1N4007 diode and add a piece of wire and some hot glue to hold it in place
        Last edited by sam_sam_sam; 06-16-2019, 07:01 PM.

        Comment

        • wadmancpu
          New Member
          • Dec 2012
          • 8
          • USA

          #5
          Re: Variac 20 amp advice?

          Thanks!

          Comment

          • sam_sam_sam
            Badcaps Legend
            • Jul 2011
            • 6023
            • USA

            #6
            Re: Variac 20 amp advice?

            I just bought the 5 amp version of it now because it getting harder to find this version when I look 6 months ago I found more Seller selling them now I see only handful of them selling them

            So I will wait until until you have all the parts and we can do it at same time

            Comment

            • sam_sam_sam
              Badcaps Legend
              • Jul 2011
              • 6023
              • USA

              #7
              Re: Variac 20 amp advice?

              Originally posted by wadmancpu
              Thanks!
              How are coming along with getting the parts to do modification to the voltage meter

              Comment

              • japlytic
                Badcaps Legend
                • Oct 2005
                • 2086
                • Australia

                #8
                Re: Variac 20 amp advice?

                I fitted mine with a self-powered digital AC voltmeter which starts to display at 60V and above - any AC product would typically not work at such a low voltage.
                My first choice in quality Japanese electrolytics is Nippon Chemi-Con, which has been in business since 1931... the quality of electronics is dependent on the quality of the electrolytics.

                Comment

                • sam_sam_sam
                  Badcaps Legend
                  • Jul 2011
                  • 6023
                  • USA

                  #9
                  Re: Variac 20 amp advice?

                  When you do the modification that I am talking about you can read the voltage down 1.0 volts

                  The reason they can not read voltage down that low has do with the voltage divider to read voltage
                  You also have voltage reducer for the meter controller


                  In order for you to read voltage down that low you need to separate the meter power supply from the meter reading voltage divider circuit when you do this then the meter can read voltages that low

                  The meter that I have a link to can easily done you just have to —>

                  ( remove one diode )
                  or
                  ( cut the trace where this diode connects to the voltage input terminal block *** you have remove the top board of the meter controller in order to cut the trace you can also recap the board while you have it separated ***)

                  —> reroute the meter voltage divider circuit and hook it up to the outlet on the Variac

                  The meter power supply is hook to ON / OFF switch which now the meter is not powered by output of the Variac supply

                  One note

                  You do need to have a meter that can read its own power supply in order for this to work

                  Line / Netural you breaking the line side of the meter power supply / meter voltage divider circuit
                  Last edited by sam_sam_sam; 06-20-2019, 08:49 PM.

                  Comment

                  • sam_sam_sam
                    Badcaps Legend
                    • Jul 2011
                    • 6023
                    • USA

                    #10
                    Re: Variac 20 amp advice?

                    Here is where I got the meter for the 5 amp version that I bought the one that I used in the 20 amp version would not fit in the same space

                    POWER GRID volt & amp monitoring GAUGE - Digital ampmeter / voltmeter combo 2in1
                    https://www.ebay.com/itm/POWER-GRID-...53.m2749.l2649

                    I will in next few days I show how I modified this meter module this was so easy to do
                    The modification to this board —> it shows where the 5 volt section for powering the meter so it can read down to ( [0] volts )

                    The modification is not finished and that is why I not showing it yet
                    Last edited by sam_sam_sam; 07-01-2019, 06:58 PM.

                    Comment

                    • stj
                      Great Sage 齊天大聖
                      • Dec 2009
                      • 30931
                      • Albion

                      #11
                      Re: Variac 20 amp advice?

                      $17 is fucking robbery.
                      i get them here:
                      https://www.aliexpress.com/item/32905549312.html

                      Comment

                      • sam_sam_sam
                        Badcaps Legend
                        • Jul 2011
                        • 6023
                        • USA

                        #12
                        Re: Variac 20 amp advice?

                        Originally posted by stj
                        $17 is fucking robbery.
                        i get them here:
                        https://www.aliexpress.com/item/32905549312.html
                        I did not want to wait a month to get it

                        I want to have this device working for a project that I want start working on

                        I am going to buy some of these meters that you gave me the link to next month

                        I have four orders from AliExpress that I am waiting for over three weeks for and still have not gotten here yet

                        Comment

                        • redwire
                          Badcaps Legend
                          • Dec 2010
                          • 3900
                          • Canada

                          #13
                          Re: Variac 20 amp advice?

                          For my variac project, I took apart that mini voltmeter and brought out the Vsense wire, so it's three wires now. It's powered off the input mains but measures the variac output, so I can dial down to a few volts AC. No <60VAC dropout of the voltmeter.

                          Comment

                          • sam_sam_sam
                            Badcaps Legend
                            • Jul 2011
                            • 6023
                            • USA

                            #14
                            Re: Variac 20 amp advice?

                            Here is the modification on this meter module that I was talking about

                            In the photo I show where I cut the trace so it can measure down to ( 0 ) volts

                            I replaced the only capacitor that is in this unit

                            It had a 330uf@16 volt capacitor but the same valve capacitor was to fat to fit in there that I had on hand so I use a 220uf@16 volt capacitor instead and seems to work okay with it
                            Attached Files
                            Last edited by sam_sam_sam; 07-07-2019, 11:36 AM.

                            Comment

                            • sam_sam_sam
                              Badcaps Legend
                              • Jul 2011
                              • 6023
                              • USA

                              #15
                              Re: Variac 20 amp advice?

                              One note about this modification is that you have to cut the trace on both sides of board in the same position which I forgot to mention

                              Comment

                              • stj
                                Great Sage 齊天大聖
                                • Dec 2009
                                • 30931
                                • Albion

                                #16
                                Re: Variac 20 amp advice?

                                you should create a bigger gap too.
                                specially people in europe with 230v - maybe even cut a slot in the pcb.

                                Comment

                                • sam_sam_sam
                                  Badcaps Legend
                                  • Jul 2011
                                  • 6023
                                  • USA

                                  #17
                                  Re: Variac 20 amp advice?

                                  You are probably right about this however there is not really a lot of trace to work with if you are putting wires to the board

                                  I did cut a deep slot in board on both sides

                                  Comment

                                  • sam_sam_sam
                                    Badcaps Legend
                                    • Jul 2011
                                    • 6023
                                    • USA

                                    #18
                                    Re: Variac 20 amp advice?

                                    Here is a picture of the meter installed I just have to cut one corner off of the metal plate so the bolt at the top will work to put back on the cover
                                    Attached Files

                                    Comment

                                    • sam_sam_sam
                                      Badcaps Legend
                                      • Jul 2011
                                      • 6023
                                      • USA

                                      #19
                                      Re: Variac 20 amp advice?

                                      Here is the finished project here are some pictures of it
                                      Attached Files

                                      Comment

                                      • sam_sam_sam
                                        Badcaps Legend
                                        • Jul 2011
                                        • 6023
                                        • USA

                                        #20
                                        Re: Variac 20 amp advice?

                                        Originally posted by sam_sam_sam
                                        Here is the finished project here are some pictures of it
                                        I used this for the first time on an old style rectifier module which I found out was working correctly

                                        Comment

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