I am using this device as a non inverting amplifier on a single supply rail of 12V. i am deriving a mid point voltage of 6V using two 10k resistors and a 10uF cap, fed into the non inverting input thru a 47k resistor. The audio input is ac coupled through a 10 uF cap.
I have a 3k3 feedback resistor, 150 Ohms and a 47uF tant to ground. The circuit is in fact the phono preamp from the data sheet modified for single supply.
My problem is that sometimes, but not always, the 6V bias on the non inverting input is dragged down to a volt or so, as though pin3 is drawing current. Sometimes touching the op amp causes it to work correctly as does injecting a fairly strong signal, probably touching is inducing mains hum..
Is it some sequencing problem with the main supply and the bias supply coming up that is causing a latch up and if so what can i do about it? I tried different cap values on the bias, but no affect that i can see.
Ideally, I know the split supply is better in many respects, but i dont have that luxury unless I use an invertor which I'm not keen on.
