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The core problem I am having is that I need to be able to control a DC to DC voltage regulator based on input from a 4 to 20 mA signal. The end goal is to have the output voltage of this regulator be able to dynamically change based on this input current signal (Output up to 24 VDC). The voltage source supplying the regulator is 24 VDC also. What I have got so far.

I want to be able to control a 10K potentiometer in the regulator using the signal form the 4 to 20 mA current loop. I have been unable to find a device or circuit that can accomplish this task.

I would appreciate any suggestions or assistance anyone could offer. I might be missing a much simpler to the problem then what i am currently trying. Thanks.

P.S. This is my first post on the forums.

mckeevew
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  • I think you're going about this all wrong, but this is also out of scope for this site I'm afraid. – Hearth Mar 19 '19 at 20:07
  • Why don't you define what the components actually are. Odds are the DC to DC takes a voltage and you need to convert the current to a voltage, which can be easily done with an op amp – Voltage Spike Mar 19 '19 at 20:12
  • Since you appear to need a current to voltage conversion, look up [transimpedance amplifiers](https://en.wikipedia.org/wiki/Transimpedance_amplifier). A very simple opamp based circuit that might do what you need. – evildemonic Mar 19 '19 at 20:14
  • Thanks for the input in the comments. The 24 volts supplied to the regulator is actually coming form a VFD's 24 VDC out terminal. The voltage is then going to regulator is going need to be able to supply around 100 mA in the end so i wasn't sure if a simply current to voltage conversion would be able to supply enough (It is a small frost prob heater). Ill have to look into possibly using an amplifier. Thanks – mckeevew Mar 19 '19 at 20:27
  • "control" - does the pot already exist and you want to turn it physically (small DC motor and linkage - high end audio amps do this), or emulate it (controlled variable resistance element like a FET or a buffered output voltage equivalent to what the pot was supplying)? – AnalogKid Mar 19 '19 at 20:35
  • Note - that resistor location is part of the compensation network for the regulator's control loop. Varying its value over a large range could put the circuit outside stable operation conditions. – AnalogKid Mar 19 '19 at 20:37
  • ~AnalogKid~ Yes i was going to try to emulate a potentiometer initially. And thanks for the heads up about the resistor. – mckeevew Mar 19 '19 at 20:42

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