so you're saying the OP is lying.

No, not a lie.
I'm saying there has to be more to the circuit than he shows

That's fine but it changes nothing about virtual grounds in single supply opamps circuits

I never said or implied that there was.
His circuit does not show any of the ways that such a virtual ground is normally achieved.

The reason this circuit works at all is due to the CA3140 input protection diodes providing a bias (albeit a weak one

Strange that you believe that since it doesn't seem to meet the critical criteria of function that you normally require.



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Strange that you believe that since it doesn't seem to meet the critical criteria of function that you normally require.

It's a possible answer of why the circuit works for the OP as opposed why it shouldn't work. Only experiment will provide actual data.

 

Did you measure it with a scope or a multimeter?

Both, first with a short across the inputs, then with an old rf multilayer inductor. An open circuit output or a 1k load made little difference!

 

Both, first with a short across the inputs, then with an old rf multilayer inductor. An open circuit output or a 1k load made little difference!

Thank you for the experiment. That data pretty much confirms the OP posted circuit conditions and results.

Will a null input (floating shorted differential input pins) you get a null output with the null output @ approx 1/2 single supply voltage in this Fail-Safe (non-textbook) mode, with this device. YMMV