DIY-Welder - Build your own Arc, MIG and TIG welder Page hits:

200A Arc, MIG and TIG Welder

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Update: March 2, 2015 Finally have some progress!

I have been fighting with the options for a new design. The original digital board was complex and expensive. Some of the complexities:

It worked, but was never something I wanted to build. Lots of expensive parts like linear optoisolators. This complexity was to allow it to be used in 3 configurations:

  1. DC welder using automotive alternator
  2. AC/DC TIG and MIG add on for standard engine-driven welders (I.e a Pipeliner, SA-250)
  3. Add on for transformer welders like an Airco, Miller DDR/3, Dialarc and others that use saturation transformers.

The simplified board was just for an alternator. It worked well but as soon as I started building it, the switches went from $1.49 to almost $6 each. It was a bit too simplified: it only drove the field voltage high, was fixed in function and did not support TIG safely.

Stick (SMAW), TIG and MIG are the goals of the board. If all you need is stick welding, the Non-Electronic Version will be all you need.

One of the problems with the simplified board was no isolation; everything was referenced to the negative output of the alternator. DC TIG is electrode negative. So, you connect the positive lead to the work. That puts the alternator, board and the entire welder metal at the OCV of the welder, usually 60V. Not a safe situation.

I have been playing with ideas to do this relatively inexpensively. The first change is to use a modern CPU like a Microchip PIC32. This will move all the voltage, current and output control from lots of analog parts to software. That makes it easier to change and add features like hot start, lift start, engine controls.

I have a schematic near done. It is not too bad in complexity in circuit or mechanically. Still not cheap as I would like, but reasonable. The features are so far:

Have some time to develop this now; no definite schedule though. Not sure on the costs yet. First boards would have to cover prototype boards, and having the panel made and silkscreened. If anyone knows a place to have the panels cut, drilled and silkscreed inexpensively; let me know. Feel free to discuss it on the Yahoo group at the top of the page.

Old Boards:


Note: I am no longer building the simplified boards.

General info on this site.

You can build a welder with a modified alternator, a few resistors and some welding cables. Can be powered by a gas or electric motor. There are several of these floating around like the "weldernators". They basically work, but have little output control. They will also likely blow out the rectifier bridge as there is no protection from the output running away and no stabilizer for a better arc. These typically run at about 20V; that will work, but hard to maintain an arc.

The idea is to have a generic control board to allow any power source with current/voltage control to be used for Arc, MIG and TIG welding. It has a programmable slope and OCV just like the big welders have. Also it supports both Constant-Voltage (CV) and Constant-Current (CC) modes so TIG, ARC and MIG can be done. It can also be used as a fast battery charger.

This can be used for a home-built welder that can be made relatively inexpensively (second prototype shown above.) The control board with a suitable motor (gas or electric), an alternator, belt and pulleys and you will have a very capable DC arc welder. 10HP electric or 12HP gas should be enough for DIY use. Add gas and a wire feeder and you will have MIG. Add a TIG torch and gas solenoid and you can do scratch start TIG. The board has a manual with all the connections explained. Most of the work is mechanical.

Scratch-start DC TIG is supported. A HF start is planned The menu at the top shows the options from a simple arc welder to a multi-process setup. There are also examples of my two prototype designs..

Questions or comments, feel free to contact me at

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