LM317 for output stage

[regiregi22]

I have been thinking that a linear adjustable regulator, like the LM317, allows you to vary the output voltage by varying the adjustment pin current.

So in theory, if you manage to vary this current depending of the voltage amplitude of a musical signal, you should be able to modulate the output voltage of the regulator in concordance.
In the same way that when you trim a pot, the output voltage varies, but in function of a musical signal.

It may sound a little funny, but with a decent slew response rate maybe the sound can be decent.

Has anybody ever tried something like that? What are your ideas for varying the input current of the adj. pin byt following a signal?

Regards,
Regi

 

[wintermute]

The answer is yes see here for an example http://www.diyaudio.com/forums/chip-amps/192934-se-class-regulator-chip-amp-madness.html

Tony.

 

[regiregi22]

Well, now I feel like comin' late to the party

Thanks!

 

[AndrewT]

and there have been a few designs from years ago posted on the Forum.

 

[jan.didden]

It becomes more logical if you consider the 317 as a high-gain medium power transistor with a negative Vbe of 1.25V
NPN of course; the 337 would be the PNP equivalent.

jan didden

 

[Elvee]

Well, now I feel like comin' late to the party

Thanks!

Have a look here (non-exhaustive):
http://www.diyaudio.com/forums/soli...sing-lm317-3-terminal-regs.html?highlight=317
http://www.diyaudio.com/forums/soli...mentary-hexfet-monstrosity.html?highlight=317
http://www.diyaudio.com/forums/soli...using-voltage-regulator-ic.html?highlight=317
http://www.diyaudio.com/forums/soli...ower-another-weird-circuit.html?highlight=317
http://www.diyaudio.com/forums/chip-amps/175457-just-fun-regulator-chip-amplifier.html
http://www.diyaudio.com/forums/chip-amps/176052-now-regulator-chip-jlh-amp.html
http://www.diyaudio.com/forums/chip...ator-chip-amp-family-welcomes-new-member.html
http://www.diyaudio.com/forums/chip-amps/193214-class-chip-amp-now-complementary-version.html
http://www.diyaudio.com/forums/chip...oss-tringlotron-regulator-chip-amplifier.html
http://www.diyaudio.com/forums/chip-amps/192934-se-class-regulator-chip-amp-madness.html

 

[wrenchone]

A former colleague of mine actually came up with an amplifier circuirt using LM317 and LM337 while working for synth maker Sequential circuits. This was back in the the late 70's/early 80's. The curcuit escapes me right now, but no doubt one of you busy folks out there will rough something out.