I am trying to bias an AC signal and to the best of my knowledge I've come up with this circuit. please be easy on me am just getting used to the concept/terms of sampling and biasing.
I am trying to get the slightest variation on of the AC signal and when simulating on LTSpice i can see a difference of .1 to .7v. Wish to know if this design would be enough for MUC such as the arduino sample. Should i smooth the signal ?
What am i trying to achieve ? A way to read the current from the secondary winding of a MOT (Microwave Oven Transformer for spot welding 18650 cells) by reading the voltage and a known resistance and by using Ohms Law I=V/R calculate the current putout during weld.
So i could use a current transducer but for the thickness of the cable of 25mm2 a CT would be very expensive. hence thought of going this way, I have two variables already which is voltage and Resistance hence within the code i could get the current. To get the voltage i have tapped on 2 points on the secondary cable at 40cm apart and i get a sinewave of 1 to 3 Vpp. So just need to scale the ac voltage safe enough to be fed into an arduino ADC and the easiest way would be to add a dc biase (i hope i've used the terms correctly) or some say it as level shifting with an opamp and some resistors and caps.