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Virtual Ground Question

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tamerakshar

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well, i saw the circuit in this forum ;but it was connected to a battery .
now if i need to connect it to an out voltage not a battery ( look to the attached picture) will it function correctly?
TeE ThE EdE
 

elmolla

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Hmm.... Not sure about the following, but lets give it a try :)

I think the concept of virtual ground here is just like the ground of the whole circuit other than the battery's negative terminal. If you want to use a voltage source you have two approaches:
1. You can use dual supplies Vdd/2 and -Vdd/2 with the ground as the VGND
2. Do the circuit as usual but the virtual ground is just a floating node from which you get your output not the usual supply ground.
 

tamerakshar

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i can't get you,
can you describe more.
thx anyway
TeE ThE Ede

MODERATOR ACTION:
Most of the users of this forum can read normal characters, there is no need for size 18. Size removed.
 

elmolla

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I think the virtual ground here acts as a ground for the whole circuit, an the shown schematic is just to get dual supply voltage of ±10V .

. If you want to use a voltage source you have two approaches:
1. You can use dual supplies 10V and -10 with their common ground at VGND. i.e. Two Chips, 7810 and 7910, with the ground node at VGND.

2. OR Do the circuit as usual but the virtual ground is just a floating node from which you get your output not the usual supply ground.i.e. with one supply of +20V get the node VGND and connect it to the ground node of your circuit, and keep the negative node or the ground node of the source away from VGND.
 

IanP

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Virtual ground concept works well in every situation, battery or any other voltage source, but, you have to keep in mind current requirements of the "new" ground ..
Resistors can be used, as in your post, or, for higher current "hungry" applications you may consider creating virtual ground by opamps/transistors .. see this publication - https://tangentsoft.net/elec/vgrounds.html - for some other ideas of creating a "virtual ground" ..

Regards,
IanP
 

hoaryhorse

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thank Ianp for ur link, now I understand Virtual Ground clearly!!
 

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