I have a sensor which gives a voltage output between 0V and 5V. I need to transform this sensor output to a current suited for a 4..20mA current loop.
The thing is, the current loop doesn't have a fixed resistance, so my current circuit does not seem to work, because as soon as you change the
RLOAD (pot in the schematic for simpification) the output current does not stay within the range.
What do I need to change to make this circuit funtion as a variable 'constant current source' (not sure how to call it, I want constant current based on the input voltage but the input will be changin).
I'd really appreciate some guidance to figure out what I'm missing!