Virtual Ground Voltage Reference

  • Thread starter teroenza
  • Start date
192
3
I'm building an Arduino voltage logger that includes an op-amp (OP27G) as a buffer on the input. Since I'd like to be able to measure voltages all the way down to zero, I want to power the amp with a bipolar supply. My initial thought was to build the rail-splitter below so I wouldn't have to come up with two discreet (plus and minus) supplies.
http://www.goldpt.com/virtual_ground_circuit.html

My question is, if I power the OP27 with the virtual ground circuit above, then the voltage logger won't function correctly unless the voltage I'm trying to measure is also referenced to that virtual ground? I was hoping to use the logger to record voltages from various sources.
 

berkeman

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I've found floating grounds like that to be problematic. Have you looked at the LM324 family of opamps? Its input voltage range includes ground. I use an LM324 input opamp stage to shift the input signal up to some reference voltage first, and then process the signal from there...
 
Last edited:
192
3
Thanks. The virtual ground circuit is a neat idea, but I'd like to avoid the complexity if possible.
 
192
3
Thanks. If temperatures exceed the commercial range for me, I'll have bigger problems than the amp :-)
 

berkeman

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LOL :biggrin:
 

dlgoff

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I've found floating grounds like that to be problematic.
I've never had anything to work correctly with an offset ground reference. Well, maybe a simple MOS circuit could work with one.
 

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