Is that a good idea or am I forgetting something obvious?

[poorchava]

Is that a valid way to create artificial ground from single 12V supply? Or am I forgetting something obvious?


I need to power a few opamps in a simple device powered by a wall-wart. Signals will partially be DC, so no capacitive coupling. I need the virtual ground to be able to both sink and source a few tens of miliamps (actually, to maintain the virtual ground in the middle between GND and +12V). Technically the vrtual ground will be 6V above wall-wart DC potential, but wall-warts are isolated (at least  hope so...) so it should not onterfere with oscilloscope for example.

[free_electron]

you dont need the extra transistors for a few milliamps.
opamp in unity gain woll work. they can handle 10 to 15 mA without problems if you use something like a TS921 they can do 50 to 80 mA

[BravoV]

Made a similar thread while ago here -> Question on op-amp current capability for making V-Ground circuit

It just works using jelly bean LM358 without transistors, and also I used the quad LM324 parallel for beefier current, there is a link in there about using multiple op-amps as well.

[poorchava]

What are the 1n4148 for?

[ConKbot]

http://www.ti.com/product/tle2426-q1

If you dont mind the non-jellybean part, its a 1 and done solution.  Good for 20mA, 40V input, stable over the whole current range with 1uF on the output.

[TerminalJack505]

What are the 1n4148 for?

I'm sure they are there to provide a discharge path for the caps into +5V when the circuit is powered down. 

[dannyf]

Is that a valid way to create artificial ground from single 12V supply?

Sure, but with room for improvement.

I would simply use an audio opamp (TDA2030) configured as a follower.

[BravoV]

What are the 1n4148 for?

I'm sure they are there to provide a discharge path for the caps into +5V when the circuit is powered down.

Yep, thats correct and also quoting ciccio's post regarding those diodes.

The diode will discharge the capacitor versus the supply source (9V) at switching off, preventing a damage to the op-amp input when switching off (without it  the input may momentarily be at an higher voltage than the supply pin). An 1N4148 will be OK.

Sometimes a diode from this junction to V+ will help at start-up

[JackOfVA]

Or one could use a TI TLE2426 rail splitter. Rated to +/- 20 mA.