Dear members, I just got 2 transformer TIG welding machines which got a broken control board. I love the transformer type because they run more stable in countries with unstable voltages. And I feel pitty to dump those transformers since they are still in good shape. Though I am neither an electrician nor an electronic expert I could check diodes, condensators and thyristors of those unit and they are all o.k. Also the transformator works as it should. High voltage for iginition is also still doing its job. But the main controlboard seems to be totally broken. Anyhow it is far to old to be fixed. There are 5 LM324 on and some other ICs besides the passive elements. The supplier does no longer deliver spare parts for this type. Since all the wiring (200 Ampere) is done nicely and in good shape, and I still find proper diodes and thyristors, I kind of dislike to use the new technology (MosFET). I attached my first approach to this project, still need to learn more about single chip microcontrollers. But in order to not waste too much time being on a complete wrong track I would really appreciate some contributing ideas and remarks. You see the transformer (28V 200 Ampere and 2x 24V, 1A) which I will just use for welding up to 160Ampere, and the existing diodes and two thyristors, the resistor of 0.001 Ohm and a throttle which avoids that high voltage during ignition will damage the diodes and thyristors. I added some PUT to control the thyristors since I could not find any optocopplers with 250mA 400mW output. My may concern is the measurement of running current using the shunt of 0.001 Ohm. Maximum voltage expected there should be 0,16V in case of 160 Ampere. Is it possible to measure the voltage (difference) directly with an Arduino one? If anyone may give a hint how this could be measured best it will safe me a lot of time. Thanks in advance Ottosan
Hello Sir , Are you consider to produce a new board to replace the old one ? By the way , do you have gerber file of this PCB ? If you have , maybe we can help you .
The lowest referecne voltage that most Arduino Boards support is ~ 1 V. YOu want to measure a voltage of max. 0,16 V. So the maximum numeric value you will get is ~160. So you get values between 0 and 160. Is that enough resolution?
Most Arduino devices have no differential ADC input, but the Arduino DUE has. The voltage must be below 3,3V. I assume that this is not the case in your device. If I am right, you need additional parts anyway.
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