I need to design a +/- 4.5 symetric source using only a opamp buffer, a 9V battery and a potentiometer. How can i do it?

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    \$\begingroup\$ Start with realizing that voltages are always relative. \$\endgroup\$ – Oldfart Oct 31 '19 at 1:51
  • \$\begingroup\$ A 9 V battery's intended purpose probably includes, roughly, the typical output current compliance of many opamps. So it's a good marriage, so to speak. Is there a particular reason why you feel you need a bipolar supply and a ground reference instead of simply using a single power supply for your circuit? What are you trying to achieve? It's possible it can be done with a lot less work than what it takes to create a decent and solid virtual ground reference that can both sink and source current from either bipolar rail. In short, talk with us some more. \$\endgroup\$ – jonk Oct 31 '19 at 2:42
  • \$\begingroup\$ There exist low current ICs for the purpose. But an active, discrete sink/source ground requires a fair bit of work if you need lots of bandwidth and down to DC operation. \$\endgroup\$ – jonk Oct 31 '19 at 3:56
  • \$\begingroup\$ Consider how you might do this using only the potentiometer, then add an op-amp buffer to improve it. Sorry but we cannot do all of your home work for you. \$\endgroup\$ – Nedd Oct 31 '19 at 7:42

Why not use two resistors instead of a potentiometer? it is possible if you use a rail-to-rail opamp and low positive and negative supply currents.

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  • \$\begingroup\$ This looks more like a comment than an answer. Furthermore, the OP clearly stated that the do not have a "negative supply". \$\endgroup\$ – Elliot Alderson Oct 31 '19 at 11:51

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