Chip Amp as tracking supply for preamp
OK This may be totally off the wall, but here's the idea....
I've been looking for a low noise power supply for an ultra low noise pre-amp I'm building. (Transistor/IC... Please don't turn up your noses.) This is +/- 15 volt job.
Anyhow... I was looking at the spec for the National chip amps, and realized that they are just low noise op amps with high current output. The LM1876 (dual 2 amp devices in one package) is actually a good candidate for a dual tracking regulator.
The idea would be to build a traditional op amp regulator circuit for using 1/2 of the LM1876... (Apply a voltage reference to the non-inferting input, give it enough gain to get up to +15 volts, and let its own internal regulation and some bypass caps take care of the noise.) To generate the negative rail, you make the other half of the LM1876 a voltage follower, and drive the negative side with the mid point of the two rails. So the negative rail always tracks the positive rail. There is a circuit in Horowitz and Hill that pretty much describes this.
Does this sound worthwhile to any body else? Love to hear some comments.
This has already been discussed. In fact you will find your proposed circuit in the OPA549 datasheet. No idea if anyone actually tried it.
somthing like the psu in this maybe?
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