Super Regulator, collecting the facts

[peranders]

Good idea but what about the transistors speed? Doesn't the pass transitor be really fast also?

[PRR]

I still think of the 741 as "new". I worked with 709s. Great little amps; just don't short them.

I have and sometimes use a mixer with all 301 opamps. The 301 is a 741 with external compensation. Decompensated to Gv=10, it gets pretty good slew rate and bandwidth. Noise isn't all that bad, if you use high-ratio mike transformers. And you can short a 741/301 all day long, what a blessing!

IMHO, there is no single novel thing in the Jung Reg. All of it had been done decades before, and I'm sure he would be the first to say so. What he DID do was put together and publish a practical topology and values that does about as good as possible for just a few dollars.

> What happens when you have current limiting and the voltage is below min voltage for the opamp?

The linked schematic has no current limiting, unless I'm missing something.

If the voltage is too low for the op-amp, often it is too low for whatever you are powering. For a first approximation, you don't care what happens. But in a refined design, you better check the "brown-out" behavior does not make nasty pops and squeals that might blow up somebody's favorite amp or speaker.

[Jocko Homo]

Apparently, someone in Sweden still does. I recently did some consulting in regards to a product out of Sweden.

Somehow.......not only did they manage to use 741s, they found them in a SMD package! I can't imagine that there are enough people who still use that log to justify making it in SMD.

Yeah, you guys in Sweden really don't get out much.

Jocko

[BrianGT]

For the lab classes here at school, they mostly use the 741, and sometimes the 351. The 351 measures much better, but isn't as stable.

I guess it is one of the cheapest general purpose opamps that you can get.

--
Brian

[Da5id4Vz]

My recollection of the 741 is that its something of the Swiss Army op-amp, not the quietist thing in the world, but you could design all kinds of stuff around it.

Kind of like having a pocket full of 2n222.

[andy_c]

Originally posted by peranders
Good idea but what about the transistors speed? Doesn't the pass transitor be really fast also?

Per-Anders,

Why not try a simulation of the circuit using LTSpice? It's pretty easy to bring in the Analog Devices op-amp models, and they do a good job of modeling all the poles and zeros of the transfer function, as well as many other things. See http://www.analog.com/UploadedFiles/...01016AN138.pdf for more details. For my simulation, I used the MJE15030 for the pass transistor. Note that the simulated ft vs current of this model matches very well with the data sheet curves (see http://www.diyaudio.com/forums/showt...533#post245533 You'll find that it won't be stable if you assume the 100uF load is an ideal capacitor. To fix this, you can go to ALW's site and find the vendor of the capacitor. Then go to that vendor's web site where you'll find curves of impedance vs. frequency which should allow you to get a good approximation of the capacitor model. I'd be glad to help, but only if you put forth the effort to set everything up first.

[peranders]

Originally posted by Jocko Homo
Apparently, someone in Sweden still does. I recently did some consulting in regards to a product out of Sweden.

Somehow.......not only did they manage to use 741s, they found them in a SMD package! I can't imagine that there are enough people who still use that log to justify making it in SMD.

Yeah, you guys in Sweden really don't get out much.

I know that 741 is still around but why would you choose this opamp if it was for new design? OK if it was to be replaced only in an excisting circuit but otherwise?

[peranders]

Originally posted by PRR
IMHO, there is no single novel thing in the Jung Reg. All of it had been done decades before, and I'm sure he would be the first to say so. What he DID do was put together and publish a practical topology and values that does about as good as possible for just a few dollars.

Walt Jung points out that he isn't the inventor of the circuit.

[janneman]

Originally posted by john curl
If it was up to me to 'improve' this regulator, I would try to use a video IC for the gain. This would give, all else being equal, faster response, more linear feedback control, and about the same noise.

John,

I am sure that is the way to go. Not only for regulators, also in other audio-related applications. For one thing, you get low THD not just at 1kHz but out to 100kHz.
However, I would hesitate to give the details about this next revolution in audio to Per.

Jan Didden

[Elso Kwak]

Originally posted by janneman



John,

I am sure that is the way to go. Not only for regulators, also in other audio-related applications. For one thing, you get low THD not just at 1kHz but out to 100kHz.
However, I would hesitate to give the details about this next revolution in audio to Per.

Jan Didden

Hi Jan and John,
Faster is better? I doubt it! But the current trend is like that. I tried some pretty fast opamps like AD817. Not my piece of cake.
Per-Anders what are the real motives to start this thread? Collecting facts? Then you have only to copy articles from the net and the Audio Amateur journal. Your QSXPS on your site is in fact a Jung like regulator with a Darlington pass transistor and a LM431 as the reference.