EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: Dan Moos on April 30, 2016, 02:55:18 pm
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My project requires a 5 volt supply for the digital stuff, and a +/- 6 volt supply for analog (audio) stuff.
For now, the power source is a bench PS set at 15v.
Which of the following topographies sounds best?
An LM7805 feeding the digital, an LM7812 feeding the analog, with a resister voltage divider (pair of 100k's) providing a reference voltage for all my opamps (this is what is currently up and running)
OR an LM7812 feeding the same voltage divider, and using the center point of the divider as the zero reference, so I have +/- 6 volt rails. I would feed this to the LM7805, again using the
center point of the voltage divider as my zero reference. As I right this, it occurs to me that 6 volts isn't enough to feed the LM7805, so lets say I have dealt with that (say, +/- 10v rails instead for the higher voltage reg). Is this a bad way? My biggest worry is noise on the analog signals.
Method 2, if its even viable, allows me to not have to send a reference voltage to each of the 32 opamp buffers my design requires. Maybe that's no big deal.
Its possible (likely actually) that my final design will run of mains, in which case getting a +/- supply is a little easier, and I just ditch the voltage divder.
But I at least want to know the best way right now when I'm running on the DC bench supply. Also, It would be nice to not need any parts beyond what I already have if possible. I'm open to that though.
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