dc42:
To expand on Marks' reply, for the "virtual ground" I suggest you add a 220K resistor between pin 3 of the LM358 and +5V, and put a 10uF capacitor in series with R1. This will keep the LM358 in the linear region. The reason for using 220K rather than 100K is that the LM358 does not have rail to rail output, instead its output can go from just above zero to about +3V (depending on load) when running from a 5V supply.
No, that's not right, both opamp inputs refer to ground, and virtual ground has to be
stiff. The traditional way is to split supply with a resistor divider (plus a decoupling
capacitor to true ground), use a unity-gain opamp stage to stiffen it up (make a low-
impedance virtual ground)
This diagram I found is the idea
(but you need to decouple the lower resistor in the divider or you have
a large noise-source! The output resistor isn't useful either. The opamp
used should be low-noise if your circuit needs to be low-noise.
In the original circuit the feedback network has a 1k resistor to ground from pin 2 - that also
needs to go to virtual ground and that ground has to source/sink current without
changing, hence the need for an actively buffered virtual ground.