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anyone interested in a jung regulator pcb group buy?

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#362
Per Anders: Instead of the Jung regulator, where the zener is de-noised by re-use of the main regulator, why not make a small pre-regulator just for de-noising the Zener?

After the Zener (LM329) can use a direct (better) coupling between opamp and series reg transistor. I think it would be better, and today there is really no reason to save the few bucks, it makes the Jung regulator cheaper, instad of just using one more regulator.

Please comment 🙂

Lars

Below an experimental board with this kind of reg. Didn't get the LM329 in yet ... (so the test board is fitted with a normal -more noisy- zener).
 

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#363
giolight said:
here voltage on the 317T with load: Vin29,3- Vad.24,4- Vout25,2
Click to expand...


This Vref is 0.8 V which is too low so the reg attempts to increase the output voltage to try to raise the Vadj. In this situation I would expect a higher Vout, like 28V or so. Hmmm.
Could it be that your resistor divider from Vout to Vadj and Vgnd is incorrect? Or maybe you have a large (leaky) cap across one of those resistors? What else is connected to that Adj pin - diodes?

Jan Didden
 
#364
the resistor from Adj pin to ground is 1K as is from Out to Adj. The cap from Vadj to ground is 47mF as is in the schematic. The voltage stated in the post above refer to the pre-reg loaded with the reg. and the reg loaded with 10K resistor. I have mounted six positive boards and all measure the same with few millivolt difference.
Giorgio
 
#367
HI,

I finally have a built up version of the regulator working in my cd player. Boy, I left these to the side for so long. I am using the 5v version to power the digital filter in my cd player, the results are good so far way more low level detail and smoother highs., I'll need more time to fully evaluate though......

Next up I will be supplying the dac's with their own super reg supplies, 5v version.

Also a question for Andy, remember I mentioned a use for valves? I would like to try the reg's on a dht stage on my cdp for the filament supply. Trouble is the output required is only 2.78 volts, I assume this is too low for the TL431? Can you suggest a suitable part please?
Thanks
Raja
 
#370
rbroer said:
Don't think 2.78 Vdc output voltage will work.
Remember this output voltage is also used to power the opamp; 0-2.78V isn't a lot for an opamp to operate on...😱
Click to expand...


Rudolf,

In this case one could power the error amp from the unreg input voltage (possibly via a prereg). The same with the reference, which could be divided down with two resistors. Alternatively, use a standard 2.5 v ref as used for DACs, AD has many in their inventory. That should work.

Jan Didden

PS Nice avatar.
 
#371
Raj1 said:
Also a question for Andy, remember I mentioned a use for valves? I would like to try the reg's on a dht stage on my cdp for the filament supply. Trouble is the output required is only 2.78 volts, I assume this is too low for the TL431? Can you suggest a suitable part please?
Thanks
Raja
Click to expand...
Low voltage _may_ be accomplished by some good Rail-to-rail opamp, TLV431 (1.2 volts) or some other 1.2 V reference and suitable gain.
 
#372
I have tested -3.10 V with the following config:

BD140
BC550C
AD825 with gain 2
LM337 with gain 2
Voltage reference red LED 1.55 V
Red LED as voltage shift for the AD825 output
Output current 300 mA (10 ohms load)

Works good, but I haven't tested with + 3.3 V.

I notice that AD825 seems to work far below 6 V which is drawn in the diagrams.
 
#373
Hi Per,

You're right, it might work.
Looking in the AD825 datasheet at the +5V/-5V specs, it seems the output voltage swing is limited to the rails minus about one Vbe drop.
Using a LMx85 for reference and voltage shifter (or 4148 diodes) and a gain of slightly over 2, it might work.
AD825 will have degraded performance at this low supply however.
 
#375
Hi,

Thanks for the responses guys.

I have found plenty of opamps that work well down to 2.5v or so, so I don't think that's a problem. There are many 1.2 volts references too. so I assume I can just use a good 1.2v reference and I should be ok........


Thanks
Raja
 
#376
peranders said:
I have tested -3.10 V with the following config:

BD140
BC550C
AD825 with gain 2
LM337 with gain 2
Voltage reference red LED 1.55 V
Red LED as voltage shift for the AD825 output
Output current 300 mA (10 ohms load)

Works good, but I haven't tested with + 3.3 V.

I notice that AD825 seems to work far below 6 V which is drawn in the diagrams.
Click to expand...
I have tested positive voltages also.

+5 volts out
D44H11
BC560C
AD825 with gain 2
LM317 with gain 2
LM431 set at 2.50 volt (via 330 ohms)
Red LED as voltage shift for the AD825 output
Output current 500 mA (10 ohms load)

Output was was 5.008 V. Good regulation


+3.3 volts out
D44H11
BC560C
AD825 with gain 2
LM317 with gain 2
Red LED at 1.65 volt (via 330 ohms)
Red LED as voltage shift for the AD825 output
Output current 330 mA (10 ohms load)

Output was was 3.31 V. Good regulation

In both cases the AD825 was fed from the output.
 
#380
Wow, still activity here!

Hi guys,

Nice to hear from the latecomers to the build, especially Raja's heart-warming comments about the sound !

For those with problems with the pre-reg voltage (e.g. Giolight), change R2 / R3 to 499R.

It seems that on some brands / batches of 3x7's the 1K doesn't provide enough current to operate the reg properly, halving the value works fine, either swap for 470 or 499R or add another 1K in parallel with the 1k's already there.

Also for the 5V option, use the LM336-2.5 in place of the TL431 - this is a drop-in replacement for the LM329 which saves some fiddling the orientation of the TL431 and works better.

For ultra-low V operation some care in biasing would be needed, to ensure the op-amp is operating in the right modes - watch out for example on some rail-rail op-amps, they have a FET input augmented by a bipolar stage, which can bring variations in performance or 'crossover' effects if biasing isn't correct.

Anyone who's emailed me re: more boards, I have some more and will get around to emailing you back soon, but feel free to 'prod' me if you wish, finding time to deal with the demands is often the biggest challenge, especially with the demands of family life!

It's very possible but not DC wise. I get more than 5 digit precision from zero mA to 300 mA.
Click to expand...

The regulator has almost no DC response to anything, due to the topology, it's hardly the most important thing for audio though 😉

Regards,

Andy.
 
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