I need to find a way to establish a conditioned 4-20ma or 0-5VDC signal with a digital input (8 bit). I know I will need a DAC but I am unsure how to maintain a stable voltage under different load conditions. I have used signal conditioners in the past but I need to breadboard this circuit. Any help would be appreciated as I am not a wiz with electronics.
Well creating a true analog voltage output of a range of 0-5vdc with 256 steps of resolution is possible using an Arduino. One method is to use the internal pwm analogWrite() feature of the arduino. This is already an 8 bit resolution signal and just needs a simple external low pass filter to convert from pwm to a pure analog voltage value that corresponds to the pwm duty cycle value. What then remains is to determine the load resistance of what you plan on wiring this signal to. If it's a high impedance input device then just the low-pass filter (a simple resistor/cap network) alone might be all that is required. If however it is of a lower input impedance then a simple op-amp buffer amp would be able to supply the needed drive requirement.
So what does the signal wire to and what is it's input impedance?
Lefty