Monday, October 15, 2007

MIG Welder: part 1

Now that my arc welder is done, my journey to the dark side is almost complete.

The MIG attachment is simple in theory, but there are a lot of things to make for it.

The electronics are split into four parts:

1.) Arc voltage sensor board - Conditons measured arc voltage, generates error signal from difference in actual voltage and target voltage, and provides speed voltage for next board.

2.) Voltage-controlled PWM board - based on voltage from arc sensor board, run motor at between 5% and 100% of rated speed at 12V using Pulse-Width Modulation.

3.)MIG relay board - has relays for welding current, wire feed, and gas valve. Both the wire spool and gas valve and be independantly engaged to allow for wire spooling and gas purge. All activate when the MIG trigger is pulled.

4.)12V+/12V- Power Supply - Provides the power for the other boards, since the arc sensor uses opamps for analog addition/subtraction, the voltage needs to be able to swing below zero.

The PWM, power supply, and relay board are tested and work. I haven't rigged up something to the arc board to test it yet.

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