I'm using the arduino to measure [45~60] volt DC. I made voltage devider with capacitor parallel to R2
R1= 20k, R2= 1k, C=100uf 16v
so this theoretically should able the arduino to measure up to 100 volt (equal to 5 volt on the analog input).
but what is happening that the read values are unstable and goes up and down about 1 volt randomly.
I think the problem that the arduino doesn't draw enough current to measure the value.
is there a specific and definite current should i give to arduino to works right ?
or there is another problem ?
please note that I measured [20~30] volt perfectly with voltage devider
R1=10k R2=1k C=100uf 16v.