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enter image description hereI'm working on a 9V VCO (synthesiser) that has three op amps, of which two needs virtual ground. So far I've been using voltage divider with a couple of caps and it works. I wonder if I need a separate power supply for each op amp? Is the TLE2426 any better? Do I need two of the TLE2426 for the two op amps?

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You should have no issues running multiple amplifiers from the same virtual ground. However, the virtual ground circuit itself will depend on what your circuit is doing. If you will be driving DC levels, you can't use a simple voltage divider without any buffering, for example. This is a good page that gives an overview of virtual ground techniques:

http://tangentsoft.net/elec/vgrounds.html

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Using a voltage divider with a decent capacitor to 0v usually does the trick for several op amps but you can bolster the mid rail up with a dedicated op amp as a unity gain buffer.

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  • \$\begingroup\$ Excellent! What resistor value should I use for the voltage divider? \$\endgroup\$ – alkopop79 Nov 9 '13 at 11:34
  • \$\begingroup\$ 10k ohm is a sort of standard default value but if running from a battery 100k might be considered. A circuit might help spot any pitfalls. Is it a linear vco or log vco? \$\endgroup\$ – Andy aka Nov 9 '13 at 11:38
  • \$\begingroup\$ Logarithmic but the CV stage has an antilog amp. \$\endgroup\$ – alkopop79 Nov 9 '13 at 12:47
  • \$\begingroup\$ @alkopop79 I wouldn't mind taking a look at the circuit design so if you get a chance please do post it. \$\endgroup\$ – Andy aka Nov 9 '13 at 13:22
  • \$\begingroup\$ @alkopop79 I'm not recognizing the log part of the vco - i can see that T1's collector discharges cap C1 but won't this be at a rate dependent on i/p voltage not log(i/p)? I's nothing to do with your question of course! \$\endgroup\$ – Andy aka Nov 11 '13 at 19:56

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