I'm trying to develop a 4ma-20ma loop from an 0.97(4ma)-2.75(20ma) input.
This input comes from the output of a low pass filter of a PWM module. I've searched the web quite thoroughly but all the circuits I come across are the typical 1V-5V with the 250 ohm resistance after the r2r op amp.
Is there any way I can implement this without using a gain stage before?
As I can't implement this with a fixed resistor as I need my resistor to somehow change from 242-137 ohm.
UPDATE1:So i figured out how to scale down the output to 0.5-2.3 this way I can use a gain stage to atleast get a 1V-4.6V Output but this way my max will be at 18ma instead of 20.Any suggestions?