I'm a beginner with electronics, so everything has to be explained in simple terms to me.
I have an Arduino with a program which provides a value via the Analog output, so that is anything from 0-5 V.
On the other side, I have a VFD with an IO card which allows it to connect to a 4-20 mA current loop, to vary the speed of the motor accordingly.
How do I convert from, let's say, 0-5 V output (PWM) from Arduino, to the 4-20 mA in a somewhat cheap and safe way (I don't want to destroy the VFD [and possibly the Arduino])?
Currently, I am using the circuit below:
The problem is that the simulation on "Multisim" is giving accurate results. However practically, the circuit did not give the accurate results.
- When V = 5 V output (from Arduino analog), I = 20 mA (V=IR) --> which is correct
- But, when V = 3.3 V output (from Arduino analog), I = 16 mA (V=IR)--> which is incorrect, as it should be 13 mA
Will this circuit work practically