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A Variable Power Supply and Battery Charger

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  • A Variable Power Supply and Battery Charger

    This is a very handy tool to own. It's a variable power supply and battery charger with 2 ranges, 0-8 volts, and 0-16 volts. I bought mine at the local surplus store, thinking it was a working unit. It turned out it wasn't and it only put out 5 volts, which dropped to 3 volts after a couple minutes. I did some serious cleaning, and got mine to look as nice as this one on ebay. I took the case off and checked the transformer and selenium rectifiers. The rectifiers were bad, and I found a pair of full wave bridge rectifiers for only $2 on ebay, but had to wait a few weeks for them to come form China. I tried to buy local, but with Radio Shack and my favorite electronics surplus store both gone, that pretty much only leaves ebay to find many parts.

    I tried to find a matching pair of selenium rectifiers, but could only find small ones with large prices. I mounted the bridge rectifier to a 3" x 6" piece of aluminum to act as a heat sink. The new rectifier is rated 1000 volts and 25 amps, which you can see I marked it in the picture. This is a handy tool to use for testing cutouts, generators, blower motors, lights, horns, etc. because you can control the voltage and monitor the voltage and amps without having to wire up additional gauges.

    BTW, the selenium rectifier is what usually goes bad in older battery chargers, and can be easily fixed by replacing it with a diode or two.
    Here's 4 pictures of my repair and a link to a nice looking one on ebay. My last picture shows me testing a 6 volt blower motor, and it draws 5 amps at 6.2 volts.
    BTW, that large capacitor is to give a smoother output, more like that of a battery.
    You do not have permission to view this gallery.
    This gallery has 4 photos.
    Last edited by Tom Wesenberg; 10-22-2017, 08:53 PM.

  • #2
    Tom, I'd like one that works the way it should. How much would it cost, from you, with a 1 year warranty ? Paats hard on stuff P.S. I put a bid on this one, since it sounds like you could fixer up for me ! Pats feeling like a user again and probably won't get no sleep tonight.. We need to meet at my friends shop sometime on Hager Hill, Wis. across the bridge from Red Wing. He's got work and storage space for us. His name is Karl and he's the one in my avatar. Old younger friend with work ethics. He had blood poisoning 5 days ago and I about lost him, he would love your energy. Pat
    Last edited by pAAt; 10-22-2017, 09:13 PM.
    Model A's and of course the famous AA's


    • Mitch
      Mitch commented
      Editing a comment
      For an extra $250.00 you can get the LIMITED lifetime guarantee. Excludes shipping and abuse

    • pAAt
      pAAt commented
      Editing a comment
      250.00 I could retire......? Oh stuff... Never mind !! Pat P.S. - Abuse is in really small print my friend !!

  • #3
    Well, that sure sold fast. Did you buy it Pat?


    • pAAt
      pAAt commented
      Editing a comment
      Offered 50.00 ? Don't know yet Tom. I'll check though.

  • #4
    Here is one tested and working Buy it now w / free shipping
    3 ~ Tudor's
    Henry Ford said
    "It's all nuts and bolts"

    Mitch's Auto Service ctr


  • #5
    Originally posted by Mitch View Post
    Here is one tested and working Buy it now w / free shipping
    I was just going to post that link also. I don't like rust, so I'd have to take it apart and repaint it, but that is also a good buy.


    • #6
      Yup, it's mine Tom. Guess I should have offered 45 instead of 50. They call me the "loser" behind my back, but loud enough for me to hear ;)
      Model A's and of course the famous AA's


      • #7
        Pat, now you can go to Menards and buy a red and black pair of battery clamps for about $1, then get a couple terminals and a couple 4' lengths of 12 gauge wire.
        If I hadn't posted about it you might have bought it for $45, but you also might have lost it over that $5.


        • pAAt
          pAAt commented
          Editing a comment
          Thanks Tom ! I think once I get to know this thing, it's going to suit me just fine. Might have to sell it to Karl and buy another one Being nice really sucks some times !!

      • #8
        Never mind, I'll give him the pretty one ! Before I use these I would like a good talking too, Tom.
        Model A's and of course the famous AA's


        • #9
          BTW, if you need a full wave bridge rectifier for any projects, here's a link to the dollar ones I bought.


          • #10
            hey Tom,
            can you provide a schematic to show how that cap is wired up?

            I don't think I have seen a charger with a cap......if it smooths the waveform, i hafta think the plates would like it better?


            • #11
              I bought an NOS owner's manual on ebay for my EICO 1050 for $6. Here's the schematic from it.

              Eico 1050.jpg


              • #12
                Interesting way they change voltages. In 12 volt mode, you get a full wave bridge. In 6 volt mode, you get two half wave rectifiers. Might get more current using that scheme, and the transformer secondary would be doing 50% duty cycle. Hmmm...

                Selenium rectifiers are still used in some applications today because of the way they fail. Silicon diodes typically fail to dead short. That means a dead short across the transformer, sometimes leading to its demise. Selenium rectifiers just slowly build internal resistance until they eventually fail as an open circuit, causing no damage to the transformer.

                I have a broadcast transmitter full of selenium rectifiers. If a stack is failing, I get plenty of notice as the B+ slowly decreases over several weeks. Far better than BANG!!

                On the other hand, if a selenium rectifier burns up, you better not breathe it in. If you do, it is likely fatal.


                • #13
                  Yes, the 6/12 switch will use the transformer secondary windings in parallel in the 6 volt mode, and use the windings in series in the 12 volt mode. Thus the 6 volt setting has double the amperage rating and a larger selenium rectifier. I never did research how the selenium rectifier is built, so I don't know exactly why or what fails in them. Just glad I could get this going again with only a dollar part.

                  The variable voltage switch sweeps the secondary windings just like the old Marx and Lionel train transformers do.
                  My dad used to have a bunch of selenium rectifiers, but gave away all his electronics when we moved from NY to MN.


                  • #14
                    I have a 1064 which I think is just newer as the schematics are the same. I got it to replace the automotive type 6V battery that runs the lights and vacuum pump on my
                    Sun distributor machine. The problem I have is when you set the power supply to 6V and turn the distributor machine on you have to readjust the voltage them when you
                    turn the vacuum pump on you have to readjust the voltage again. The main problem I have is when you turn the vacuum pump off the voltage jumps to about 10V and the
                    light bulbs in the instruments don't like it. Is there any way to add some type of voltage regulator.


                    • Tom Wesenberg
                      Tom Wesenberg commented
                      Editing a comment
                      Connecting a 6 volt battery would be the easiest way to control it. The bigger the battery, the better the control. A car battery would be ideal, but even a 6 volt motorcycle battery should work quite well.

                    • Bob C
                      Bob C commented
                      Editing a comment
                      Thanks Tom but I'm trying to eliminate having to have a 6V battery to run the distributor machine.

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