High frequency start box

start_box

When welding with an AC arc welder, it is often necessary to “scratch start” them to get the arc going. For those unfamiliar, it is just like it sounds. You drag the head across something just like a giant match. There are some that come with an arc stabilizer or “high frequency starter”. This is preferred, but they can be hard to find. [Bill] shows us how to make one of our own. Though you may have an easy enough time finding a big transformer, you might run into some difficulty finding the capacitors, and tungsten spark gaps. If you manage to get your hands on them, you can follow [Bill]’s schematic and build one of these starters for yourself.

29 thoughts on “High frequency start box

  1. My first thought an auto ignition coil will not stand up to continuous duty. Second thought was that my be why it’s labeled a start box not a HFHV arc stabilizer and what appears to be foot switch. Third though was #8 wire in pretty puny when compared to my welding cables. The only other feature I could think to add is current sensing, along with time delay. That would sense an attempt to start the arc, turn the box on and, turn it off when the welder had time to establish the arc. Allowing one to get rid of the foot switch

    1. That is the basic idea behind a lift arc start welder. When you touch the tungsten to the workpiece, the welder senses a short circuit, than when you lift the tungsten back up the welder senses that the circuit is now open and starts a high frequency arc.

  2. Why Tungsten? I would imagine Tungsten has an extremely high melting point and has a good resistance to arc oxidation. So they last a lot longer.

    1. The purpose of the spark gap is to isolate the HV supply from the 200 amps of current from your welder that would fry you HV power supply faster then building 7 went down if directly connected!

  3. green coded tig welding electrodes are almost pure tungsten. they are available from welding suppliers in many different diameters. a spark gap can be made from a couple pieces of an electrode that are shimmed apart.

  4. Spark gaps because its simple, spark gaps never blow up like a transistor. Im sure theres probably also some better reason related to the incredibly high frequency.

  5. To be able to superimpose this high frequency signal on the secondary of the welding transformer, you also need a high-pass filter connected in paralel with the secondary winding.
    Otherwise the high frequency signal will feed back into the primary.

    1. Hi, I am very new to tig welding and have just got an inverter tig welder thats scratch start. my question is, do the keep the arc starter connected all the time while i am welding or is it just switched on to get the arc then switched off. thansk for help.

  6. Hi!
    The arc starter works really good !
    You dont need touch the stick electrode with the work to initiate the arc. Very usefull for low current weld.
    Thanks to Willian F. Dudley Jr. that published the schematic PLEASE NOTE THATH THE 500 pF capacitor is TO BE CONNECTED IN SERIES with the primary of auto ignition coil. 100ohms not required im my assembly.
    Also the auto ignition coil was replaced with a homemade transformer primay 10 turns #22awg, secondary 300 turns #28awg, core from a tv flyback “c” 200mm2 cross section, insulation between layers 0.12mm polyester paper. No more than 38 turns in each layer. Alkid (exterior spar vernish or sparlac)impregnation.

    The termminal of buzz box to be shunted with 0.5mF x 400v cap to prevent HF voltage enter into the main weld machine

    Enjoy

    Newton

  7. By the way, the 500pF x 30000V capacitor was replaced by a 1000pf x 20000V home made capacitor

    Material required : aluminun foil used at kitchen and glasses from home windows.

    Enjoy

    Newton
    Newton.b@live.com

  8. Yes, it works very fine. Connected to the buzzbox allows u weld very confortable at 30-80A.

    The schematic has a mistake: 500uuF in parallel with the 10 turns primary.
    To fix make the 500uuF cap in SERIAL with the primary 10 turns coil.

    The 500uuf capacitor was made with windows glass e aluminiun cook foil.

    The tesla coil was simplified too, using simple ferrit beats found in scraped computer monitor.

    Assembled with 2 gaps only,

    At all is very effective device to help weld at low currents.

    Newton Brawn,
    newton.b@live.com

  9. Info gleaned from Miller HF-15 manual(TM-610A ,Sept 1997):
    Can be used with other processes such as Plasma Arc Cutting! (hint hint)

    Spark gap is .008 inch.

    High voltage transformer steps up voltage from
    115v to 3000v(three thousand).

    High freq produced is approximately 1 to 2 megahertz.

  10. I know the post talking about the coil standing up to continuous duty is way old but I would like to point out that a car coil should do fine durability wise. On a V8 engine a conventional coil would fire around 400 times per second at 3000 rpm. 3000/60=50 full engine rotations per second. The coil fires once per spark plug. For a V8 that would be 8 firings per revolution so 50*8=400. An automotive coil has a service life of years and is cheap to get as well as easy to deal with.
    Just wanted to point that out for anyone coming across this information.

  11. I recognise that this article (and posts) are very old,but can asnybody provide schematics for this project please.
    Thanks Rob.

  12. Can someone build me one of these? I like to work with old vintage welding equipment and this would be a nice add-on to an old dinosaur stick machine I have.

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