I recently dove back into my old stacks of magazines and found a similar circuit which, IIRC, used two transisters and an opamp to create a split power supply from a single source (such as a 9 volt battery). This virtual ground chip looks cool though, especially in the little to-92 package! -Adam Lawrence Lile wrote: >I looked up "virutal ground" on ti.com, and found this: >http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=TLE2425 > >It is budget priced at US$0.75, and only handles 20 mA max, which would be >two LEDs. I'm driving 8 so this would cost about $3.00 for enough virtual >grounds. Probably out of my price range, but a really cool idea. > >I think I will order some samples for my next analog project, this looks >like a really cool device! > >--Lawrence > >----- Original Message ----- >From: "Reginald Neale" >To: "Lawrence Lile" >Sent: Monday, February 04, 2002 7:30 PM >Subject: Re: [PIC]: Driving a dual LED > > >>>I understand how you would do this with an op amp - what is a "virutal >>>ground" device? Part numbers? >>> >>>--Lawrence >>> >>I was afraid you'd ask that. It's been a while since I looked into >>it. Seems to me TI and AD both make such a device. IIRC the opamp and >>dividers are integrated on-chip so you can get one in a TO-92 pkg >>with only 3 terminals: V+, V-, ((V+)-(V-))/2. >> >>Reg >> > >-- >http://www.piclist.com hint: To leave the PICList >mailto:piclist-unsubscribe-request@mitvma.mit.edu > > > > > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu