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SCR Circuit Problem

  1. Dec 31, 2007 #1
    I came across a circuit online to vary the 220V input into a welder. This is done to control the amount of current entering the piece being welded, using a foot pedal. The circuit has worked for many people.

    I built the circuit, but it doesnt work. R2 blew when I would crank the pot up, and there was no current entering the welder. I dont know if the SCR fired or not, but it wouldnt weld or make a spark what so ever.

    My initial thoughts are that the circuit was designed for a particular type of SCR, and mine isnt compatible.

    Also, im an EE student but im just starting out, I have some circuit theory under my belt, but im not sure on what to use as a voltage in this circuit, as its all part of the 220V line.

    Can anyone help me out?

    Sorry for the size of the pictures, but I wanted to keep the detail.

    Thank you!

  2. jcsd
  3. Jan 1, 2008 #2
    In my lifetime I have worked on all kinds of complicated equipment, including welders and they are the worst because they are a basic power supply.
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