Not strictly a mach question but...
a potential divider gets me the (negative) voltage of the torch (0 to -ve 300Vdc) down to 0 to -ve 5Vdc. I then need to feed this into an ADC. However the input range of the ADC is 0 to +ve 5Vdc. I'm looking at using an op amp as a unity inverter but that's where my electronics gets a little sketchy. I don't really want to get involved with split supply and as the input will allways be -ve I don't think it's neccessary anyway. But... do I need a negative supply to the op amp? Basically I'm a bit lost - are there any electronics savvy Mach users out there that can talk me through it or perhaps suggest a better way even.
So in a nutshell - how to feed 0 to -5V into an ADC that requires 0 to +5V.
Cheers
Ian