Thanks Graynomad.
Its not, I just wrote 72 as an example. As I said, it can be anywhere around 70 to 80V, although normally is around 75V.
I am starting to think it might be a bit difficut to find an easy solution for requirement
- At first I wanted to use zener diode to make a clear distinction between voltages under around 50Vdc and over it. The reason was that it should be around 75, so anything lower than 50Vdc does not make sense. However, I wouldnt mind if it can detect a range like under 50Vdc (logic 0) over 50Vdc (logic 1)
If its much more easier, I dont mind if the circuit will be activated as soon as there is any voltage on the positive. But as I say, it needs to be prepared to withstand 0 to 80Vdc.
Thank you very much all.