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In the interest of reliability, the raw input voltage should not be higher than the total opamp allowed sypply. So for the most opamps that's 36V, but some allow 44V.
Anyway, if the raw input is 36V max, the Vout max should not be higher than (precision guess) 32V or so.
Some safety factor, limit Vraw to say 33V and Vout max to 30V.
Is that not enough for almost all applications?

jan
 
In the interest of reliability, the raw input voltage should not be higher than the total opamp allowed sypply. So for the most opamps that's 36V, but some allow 44V.
Anyway, if the raw input is 36V max, the Vout max should not be higher than (precision guess) 32V or so.
Some safety factor, limit Vraw to say 33V and Vout max to 30V.
Is that not enough for almost all applications?

jan

I need 36 for the phono. Oh well.
 
I need 36 for the phono. Oh well.

Hello,

What phono stage needs 36 volts anyway ? Is it AC coupled or a tube design? SOme of the lowest noise jfets with high gm will struggle with them voltages.

Most are under +/- 24volts DC...and even that can be pushing it

Kev.

PS. You can cascode the input CCS to waste unloaded headroom or change op amps.
 
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PS. You can cascode the input CCS to waste unloaded headroom or change op amps.

This should read a cascoded CCS with high gm mosfet output (or possibly pre-load the output) could be used to waste unloaded voltage headroom. I am going to dig out the original PDF and have a re-read. Make sure I am up to speed on it.

A small heatsink is advisable on top of the op amp also. You could also use very linear super-beta type transistors if it's just for a single positive rail.
 
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Sadly the PCB is now unobtanium. The bootstrapped '95 one with AD797 I am on about. . . .
It's definitely impressive when an engineering effort "gets it right the first time".

Are you referring to the schematics of Figure 1 and Figure 2 of the article in "Audio Electronics", 2000 issue #4 (see http://waltjung.org/PDFs/Improved_PN_Regs.pdf ). I believe those circuits use a slightly modified version of the PWB layout shown in Figure 4 of the "Audio Amateur" article from 1995 issue #3 (see http://waltjung.org/PDFs/Regs_for_High_Perf_Audio_3.pdf ).

If that is the case, it should be fairly straightforward to simply replicate that layout into a file package that you could successfully send to most of the quick-turn PWB houses. Since the component make/model and basic mechanical layout have already been determined, I'd estimate about 1 - 2 man-days' work. Of course, modifications or "requirements creep" can exponentially increase that estimate.

Dale
 
It's definitely impressive when an engineering effort "gets it right the first time".

Are you referring to the schematics of Figure 1 and Figure 2 of the article in "Audio Electronics", 2000 issue #4 (see http://waltjung.org/PDFs/Improved_PN_Regs.pdf ). I believe those circuits use a slightly modified version of the PWB layout shown in Figure 4 of the "Audio Amateur" article from 1995 issue #3 (see http://waltjung.org/PDFs/Regs_for_High_Perf_Audio_3.pdf ).

If that is the case, it should be fairly straightforward to simply replicate that layout into a file package that you could successfully send to most of the quick-turn PWB houses. Since the component make/model and basic mechanical layout have already been determined, I'd estimate about 1 - 2 man-days' work. Of course, modifications or "requirements creep" can exponentially increase that estimate.

Dale

Hello,

It would better if Jan designs it. I know he done tests/measurements (no easy task I hear)for Andy (ALW) and liked the PCB layout etc. I remember following the thread at the time. So he's best placed to design/improve it etc.

Kev
 
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AX tech editor
Joined 2002
Paid Member
I've layed out a revised version, using the original circuit from the 1995 series updated with Walts 4/2000 article in Audio Amateur (all available on Walt's website).
I need to do some small tuning but will then place the Gerbers and stuff on my website for free.
Single board for pos and neg version which can be separated.
Such is the pleasure of a rainy Sunday afternoon ;)

jan
 

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I've layed out a revised version, using the original circuit from the 1995 series updated with Walts 4/2000 article in Audio Amateur (all available on Walt's website).
I need to do some small tuning but will then place the Gerbers and stuff on my website for free.
Single board for pos and neg version which can be separated.
Such is the pleasure of a rainy Sunday afternoon ;)

jan
Q1? Check the placement against the heatsink.

Notice also that you have acid traps (angles less than 90 deg) on the pcb, near J1 for instance. I don't use square pads very much. Pretty tight in some locations.
 
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