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Old 28th December 2009, 09:41 PM   #41
acaudio is offline acaudio  Germany
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The circuit seems to be very similar with simplified Aleph ono.
Best regards, A.
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Old 28th December 2009, 10:20 PM   #42
mlloyd1 is online now mlloyd1  United States
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after reading these groups for so many years, the following response wouldn't leave my head until i typed it.

apologies to nelson for badly butchering an earlier comment of his that i especially like ...

"we don't need no values; we are fearless preamp builders.
but we have spare jfets, just in case ..."



mlloyd1
btw, thanks wayne!

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Here is the Pearl Two schematic. You will have to wait for values.
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Old 29th December 2009, 12:36 AM   #43
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@Wayne,
u r such a teaser.
thxalot

Happy new year
peter
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Old 29th December 2009, 05:55 AM   #44
ra7 is offline ra7  United States
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the first stage is similar to the pearl. second stage looks interesting. can't wait, wayne!
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Old 29th December 2009, 09:20 AM   #45
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Second stage is still a discrete OP Amp.

Clever mix of J-Fet, Mos-Fet as amplifier and Led/BJT as current sources.

Reinhard
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Old 29th December 2009, 06:45 PM   #46
Merijn is offline Merijn  Netherlands
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This is sooo nice! Can't wait to order
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Old 29th December 2009, 08:29 PM   #47
GuidoR is offline GuidoR  Italy
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Quote:
Originally Posted by wayne View Post
Here is the Pearl Two schematic. You will have to wait for values.
...or fully "open" the screen of your laptop and look at the schematic from a very open angle...and the values magically will appear...

sorry Wayne, it's

And many, many thanks, I can't wait...

Only a comment: 7824/7924: there's room for improvement, I think

Guido
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Old 29th December 2009, 10:25 PM   #48
MRupp is offline MRupp  Germany
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Quote:
Only a comment: 7824/7924: there's room for improvement, I think
Just a suggestion - I was working on a VERY simple shunt regulator that is inspired by elements from previous "passdiy" designs, so it may actually fit here. The error amp is simply a differential pair, same as in the original Pearl series regulator, followed by two BJTs for the shunt element in place of the (series) FET in the original. The current source is basically a ZEN current source.

The circuit is very simple and you can off course get "better" performance (lower impedance) by means of higher amplification factor/feedback, through a more complex error amp (IC opamp or other) - there are numerous examples out there. And you can also go on for months toying with all kinds of variations but you may just be beating the subject to death (I spent a substantial amount of time on variations of the ctoole shuntreg and will not do this again).

At least my simulations look very promising and show flat load regulation over a very broad frequency range. I am quite confident that the circuit works well "as is" though I may be leaning myself out of the window a little bit by not having prototyped it. I am in the process of building such a prototype on a PCB, but that may take some time and you may not like my PCB version anyway, so if you are interested I strongly suggest not to wait and try it for yourself to see how it performs.
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Old 30th December 2009, 12:44 AM   #49
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Quote:
Originally Posted by GuidoR View Post
...and the values magically will appear...
omfglol, this reminds me of U.S. military security defeated by copy and paste - CNET News
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Old 30th December 2009, 01:02 AM   #50
wayne is offline wayne  United States
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Default Pearl PC Boards

The boards will be arriving after we return from CES in Las Vegas.
They are sized like the Pearl and will drop in. We will sell with matched fets.

A power supply board will follow if anybody wants one. ???
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