I'm working on a project to control a TIG welder digitally. The dial that changes the main for the welder starts at basically 0v and at the top end gets to 8.52v. I'm currently using an Arduino that is externally powered to control an MCP4131, which then controls how much of the main amperage is used. The MCP works perfectly up until it gets to 5v and then dies (duh). What is a good solution for this? I need it to work at every voltage between 0-8.52v

  • \$\begingroup\$ Rread the datasheet! The voltages on the resistor pins must be between Vdd and Ground. \$\endgroup\$ – Peter Bennett Apr 5 '19 at 1:22
  • \$\begingroup\$ Welcome to EE SE! We would like to help you as best as we can if there was enough information, see more here to ask a better question. Please edit your question by showing us your schematic about how do you connect the component each other. \$\endgroup\$ – Unknown123 Apr 5 '19 at 1:24
  • \$\begingroup\$ Digital pots that have separate digital and analog voltage inputs are available. You could use one of these with a switched capacitor voltage doubler chip to generate +10V from the +5V. \$\endgroup\$ – crj11 Apr 5 '19 at 2:40
  • \$\begingroup\$ what is connected to the dial knob on the TIG welder? \$\endgroup\$ – jsotola Apr 5 '19 at 3:46

You are killing the MCP4131 because you exceed the ratings:

enter image description here

Simply buffer and amplify the 5V signal to reach your required 8.5V.
Perhaps something like this, using a rail-rail op-amp:


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Would using an MCP41HV31 be a solution, or would it have similar issues to the regular version? \$\endgroup\$ – Dylan Tucker Apr 5 '19 at 18:24
  • \$\begingroup\$ @DylanTucker of course, the MCP41HV31 would work too, I just answered assuming you already had the MCP4131 on hand. You'd need an adjustable power supply to feed the Digipot high end. \$\endgroup\$ – Jack Creasey Apr 6 '19 at 0:05

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