A PIC logic 0V output is not equal to a ground?

[HankMcSpank]

Hi Hank,

The good question might be : what does my OPA do with inputs tied to ground ???

I wouldn't know how to interpret the opamp datasheet for that kind of thing! But I do know when I hardwire the Opamp's +ve pin to ground...the circuit performs as expected (input signal is inverted)...remove the ground & the input is non inverted at the ouput. However when applying a PIC output low in the same manner - eeeeugh. That particular circuit is a fairly generic circuit & not specific to any particular opamp variant.

Nick, I'll give that a go, but I'm not confident - if a CD4066 doesn't work in situ (which as very low channel 'on' resistance), then it's likely to have a similar outcome!