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This question already has an answer here:

I'm trying to find the easy but a somewhat stable way to create a split power rails Vcc Vee for the opAmp applications. Any specific known IC for this purpose?

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marked as duplicate by tcrosley, Ricardo, Dwayne Reid, nidhin, Daniel Grillo Mar 31 '15 at 16:11

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    \$\begingroup\$ Do you mean like ICL7660? \$\endgroup\$ – Roger Rowland Mar 30 '15 at 12:08
  • \$\begingroup\$ Are you asking about virtual grounds? \$\endgroup\$ – PlasmaHH Mar 30 '15 at 12:11
  • \$\begingroup\$ yes I have DC adapters at home but I want also negative voltage output creating virtual grounds. \$\endgroup\$ – user16307 Mar 30 '15 at 12:12
  • \$\begingroup\$ I think ICL7660 is a good suggestion. \$\endgroup\$ – user16307 Mar 30 '15 at 12:18
  • \$\begingroup\$ Any voltage regulator can be used to create a new voltage rail between two existing power rails. But yes, there are some that are designed specifically to divide the input voltage precisely in half. \$\endgroup\$ – Dave Tweed Mar 30 '15 at 12:31
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You could use two identical regulators, isolate them and tie the positive rail of one and the negative rail of the other together. That's usually how it's done with DC DC converters, in case you need a high current: some DC DC converters are already isolated (some even do the entire conversion from unipolar to bipolar).

If you don't need a high current you can opt for integrated circuits like the one Roger Rowland has suggested in the comments of your question. Those ICs are basically: 1) charging a reservoir capacitor with the input 2) isolating it from the input 3) connecting its positive terminal to ground and its negative to the output terminal 4) Isolating the reservoir from the output and connecting it to the input - over and over again thanks to a clock and some logic. The output is filtered to get a smooth negative rail.

Of course, if applicable you could also use half your supply, provided by a separate regulator, as the reference instead of ground (that's what biasing does basically).

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  • \$\begingroup\$ i edited my question. would this work safely: i.stack.imgur.com/UZzPV.jpg \$\endgroup\$ – user16307 Mar 30 '15 at 13:16
  • \$\begingroup\$ 1) This architecture would work if the wall adapters are isolated (some wall adapters aren't on purpose) 2) HOWEVER when isolated from mains, you are giving up on a very important safety feature: residual current devices. You NEED to make sure the secondary voltages are inherently safe for you to accidentally touch, given the environment. The voltage between V+ and V- will be twice V+, in particular. 3) AND protect the circuit against short circuits if the wall adapters do not include any, to prevent fire. 4) This is only guidance, I shall not be dragged to court if anything bad happens ;) \$\endgroup\$ – Mister Mystère Mar 30 '15 at 13:31
  • \$\begingroup\$ please copy and paste your nice answere here. i made it a sperate question: electronics.stackexchange.com/questions/162362/… \$\endgroup\$ – user16307 Mar 30 '15 at 13:33

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