Re: [AVR-Chat] Negative bias supply for signal conditioning op-amp
2005-03-31 by Robert Payne
Maybe have a look on the National site and use their "Webbench Design Tools" and see if that comes up with what you require ? They are usually good with samples as well http://www.national.com/appinfo/webench/scripts/my_webench.cgi Cheers Rob Payne
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> I'm using a 741 op-amp to condition an input signal. It's setup like a > threshold detector to detect a voltage level between .1 and .6 volts > (adjustable). It's my understanding (and experience) that the 741 can not > operate that close to one of its rail voltages so I need to supply it > with a > negative rail voltage (I'm thinking -9v). I have 12v supplied to the > rest of > the circuitry and need to avoid having a second supply (remote > location). I was > thinking that I could generate -9v using a 555 timer, caps, R's and > diode to > rectify a negative voltage. Can someone point me to a web site > circuit for this > using a minimum of components? I assume I only need a very small current. > > In the short term (this weekend) I need to stick with the 741 which I > have on > hand but can someone recommend an inexpensive "rail to rail" op-amp > that would > be better for my final configuration which would eliminate the need > for the > second supply? > > Thanks in advance for any guidance you can give. I'm mostly listening > on this > list but I'm learning a lot. Thanks to all contributors for the resource. > Someone on the list recommended "Embedded C Programming and the Atmel > AVR" to > someone else. I ordered the book and read it in short order. I found > it very > helpful in my "getting up to speed" <g>. > > Regards, > > Chuck Hackett > > > > *Yahoo! Groups Sponsor* > ADVERTISEMENT > click here > <http://us.ard.yahoo.com/SIG=129vqqkkt/M=298184.6018725.7038619.3001176/D=groups/S=1706554205:HM/EXP=1112377886/A=2593423/R=0/SIG=11el9gslf/*http://www.netflix.com/Default?mqso=60190075> > > > > ------------------------------------------------------------------------ > *Yahoo! Groups Links* > > * To visit your group on the web, go to: > http://groups.yahoo.com/group/AVR-Chat/ > > * To unsubscribe from this group, send an email to: > AVR-Chat-unsubscribe@yahoogroups.com > <mailto:AVR-Chat-unsubscribe@yahoogroups.com?subject=Unsubscribe> > > * Your use of Yahoo! Groups is subject to the Yahoo! Terms of > Service <http://docs.yahoo.com/info/terms/>. > >