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Tool Gloat: Stored Energy Welder

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  • Tool Gloat: Stored Energy Welder

    As I mentioned in another thread a friend gave ma a Hughes VTW-29C Stored Energy Welding Supply. The is a little spot welder for doing things like welding tabs on batteries, welding filaments on and light work like that. Maximum output of 40 Watt-Seconds (Joules), it dumps the stored energy from three 200uf, 450v electrolytics though a transformer to the work head, which I don't have. Found marked inside was the date it was assembled by the girls at Hughes, end of 1961)


    Got all the missing parts from it from R5-D3 surplus for $10. I found I had one of the cam lok connectors that fit the panel in my welding drawer and have 5 more coming off ebay for $25 shipped.

    Ill probably start by making a basic head from something like an arbor press. The real ones are incredibly expensive, even used. Even cheap ones are $400 on up. About 3/4 the way down on this page, VTA prefix: http://www.emcgrath.com/catalog/welding/welding.html

    Here are a few pics, Front:


    Hughes VTW-29C Capacitive Discharge Power Supply by macona, on Flickr

    Inside in the dark, the big glowing one on the left is an OC3 voltage regulator, the small one on the right is a 12AU7, and the two in back are the 2D21 xenon thyratrons. And below that is a video of the insides working. The thyratrons glow when they are conducting charging the caps.


    Hughes VTW-29C Capacitive Discharge Power Supply by macona, on Flickr

    Last edited by macona; 04-16-2012, 01:11 AM.

  • #2
    Cool! I'm curious- you say it dumps the charge through a transformer to the work head. Do you mean inductor, or is the charge 'transformed' before being sent to the work head?

    600 uf charged up to something approaching 450 volts is a pretty high level pulse. It must be a pretty large transformer if the bulk of the charge can be transferred to the secondary. So it would seem to me anyway.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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    • #3
      They sure are a lot prettier than transistors.
      Free software for calculating bolt circles and similar: Click Here

      Comment


      • #4
        Ok, I have a love for tube driven tools. Yeah, thats why I have the tube lathe.

        So you have a thyratron rectifier there and a regulator. It looks like one of the rectifiers is not conducting?

        And Evan. Transistors? Diodes right? No signal switching or amplification going on. Just plain old rectification or in the simplest of terms filtering.

        I really like that tool. JR
        My old yahoo group. Bridgeport Mill Group

        https://groups.yahoo.com/neo/groups/...port_mill/info

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        • #5
          It stores the energy in the capacitor bank and then dumps it to the transformer through a mercury contactor. The transformer will work on DC until the core saturates which I am sure is longer than it takes to discharge. I would have to put a scope on the output to see how long it takes. The transformer has some pretty massive windings on the secondary, 3/4" wide copper strap at least.

          The thyratrons are basically the equivalent of a SCR, both are all or nothing affairs. The triode is closer to a transistor. Both of the thyratons do light up pretty evenly, just the relay is partially blocking the one on the left.

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          • #6
            Those work pretty well for charging small magnets, also. Meter magnets, etc.

            I have the manual (but not the unit) for a similar device used to charge magnets. In that one the thyratron is used not to charge, but to DIS-charge the cap bank through the transformer. Makes for a fast turn-on.

            As for the transformer, it will work fine on a pulse if the primary inductance is large enough. As is usual with such things, "it's all about the volt-seconds"... the pulse voltage vs the time of the pulse.

            Short enough and a hefty pulse of current at very low voltage comes out the secondary containing most of the energy of the cap bank, with the current increased by the turns ratio.
            1601

            Keep eye on ball.
            Hashim Khan

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            • #7
              And Evan. Transistors? Diodes right? No signal switching or amplification going on. Just plain old rectification or in the simplest of terms filtering.
              The thyratron is a switch, same as an SCR or transistor.

              Thyratrons are still in use. One use is triggering atomic bomb initiators. Solid state devices can't handle it as the detonating circuits require multi kilovolts at multi kiloamps with timing in the tens of nanosecond range (for plutonium weapons).
              Free software for calculating bolt circles and similar: Click Here

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              • #8
                Valves not tubes! Alistair
                Please excuse my typing as I have a form of parkinsons disease

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                • #9
                  Valves, usually triodes, pentodes and family are affectionately known as FETs with pilot lights around here

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                  • #10
                    Originally posted by Alistair Hosie
                    Valves not tubes! Alistair
                    youve got a spot welder with valves in Alistair

                    all the best.markj

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                    • #11
                      Originally posted by Evan
                      The thyratron is a switch, same as an SCR or transistor.

                      Thyratrons are still in use. One use is triggering atomic bomb initiators. Solid state devices can't handle it as the detonating circuits require multi kilovolts at multi kiloamps with timing in the tens of nanosecond range (for plutonium weapons).

                      Tube technology is still used for RF amplification and beam control in many particle accelerators for the similar reasons. Another plus is that they are radiation hard. All of the emergency phones in the tunnels at Fermilab, for instance, are the old rotary type. Even touch tone phones have too many electronics to recover from the radiation exposure.

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                      • #12
                        Originally posted by J Tiers
                        Those work pretty well for charging small magnets, also. Meter magnets, etc.

                        I have the manual (but not the unit) for a similar device used to charge magnets. In that one the thyratron is used not to charge, but to DIS-charge the cap bank through the transformer. Makes for a fast turn-on.

                        As for the transformer, it will work fine on a pulse if the primary inductance is large enough. As is usual with such things, "it's all about the volt-seconds"... the pulse voltage vs the time of the pulse.

                        Short enough and a hefty pulse of current at very low voltage comes out the secondary containing most of the energy of the cap bank, with the current increased by the turns ratio.
                        Never thought of charging magnets with it. Ill have to keep that in mind.

                        The Monarch 10EE also uses thyratrons. They used them until about 1983 before going skid state. After that you needed true three phase to run the drives.

                        I have an excimer laser head that uses a big ceramic hydrogen thyratron to discharge the cap bank into the tube. I can't remember the exact specs, but something like 25kv max at several thousand amps.

                        It would make a great can crusher! It's the white cylindrical unit in the pic below. On top is the trigger board which is controlled through a fiber optic cable.

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                        • #13
                          I really like things that light up while operating. Lasers, LEDs and just about anything else. My dog also loves things that light up including lasers, flashlights, even reflections as well as TV. Whenever I come home with something I bought he runs over to see what I take out of the bag and waits to see if it has lights.
                          Free software for calculating bolt circles and similar: Click Here

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                          • #14
                            http://paillard.claude.free.fr/

                            http://www.youtube.com/watch?feature...&v=gl-QMuUQhVM


                            --Doozer
                            Last edited by Doozer; 04-16-2012, 07:46 PM.
                            DZER

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                            • #15
                              Originally posted by macona
                              This is a little spot welder for doing things like welding tabs on batteries, welding filaments on and light work like that. Maximum output of 40 Watt-Seconds (Joules), it dumps the stored energy from three 200uf, 450v electrolytics though a transformer to the work head, which I don't have.
                              Cool! I have to ask the same question my Wife would ask: what are you going to do with it?
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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