JGs Nobrainer and Nobrainer Discrete - Page 4 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st January 2012, 11:36 PM   #31
diyAudio Member
 
Holger Barske's Avatar
 
Join Date: Jan 2001
Location: Ruhrgebiet
Still have an interesting problem. There are two different pinouts for the BF246A floating around on the datasheets.
Can anyone tell me if A or B is the correct one?
Attached Images
File Type: png BF246A.png (3.3 KB, 833 views)
__________________
Best regards: Holger
www.holgerbarske.com - Deutschsprachiges Paradise-Support-Forum
  Reply With Quote
Old 22nd January 2012, 04:11 PM   #32
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
That is true. The ones from Fairchild have the gate on the side and older ones from Phillips, Siemens have the gate in the middle. The only way to find out is to measure it or look up the spec sheet of the actual part you use.
  Reply With Quote
Old 22nd January 2012, 04:17 PM   #33
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I got a visit from Klangmeister Georg Stracke and we listened to his Nobrainer. He had build the original version that Holger had layed out with servo and LT1028. Martina Schner was also there on her way back from Vienna. It sounded so good that i decided not to design a fully discrete version any more but max out the original circuit. I will make a double mono PSU and Georg will lay out the boards. Each channel has to fit on half a Euro board.
  Reply With Quote
Old 23rd January 2012, 02:30 PM   #34
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
This is our listening session :http://www.georg-stracke.eu/
  Reply With Quote
Old 11th February 2012, 03:51 AM   #35
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Georg is now working on a layout :Das Leben des Klangmeisters “Nobrainer”- Phono-Stufe von Joachim Gerhard …Update…
I designed a PSU that should work really well.
  Reply With Quote
Old 17th March 2012, 03:23 AM   #36
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
I have good news. PCBs for the Nobrainer are now available. All is modular and Mono so we have a Phono Board, the Shunt Regulator and the Pre-Regulator. I will publish some pictures and more information soon. The boards have being layed out by Klangmeister Georg Stracke and manufactured by Fischer in Germany. The quality is FR4, 2-layer with position print. From 100 pieces prices are competitive.
  Reply With Quote
Old 22nd March 2012, 04:18 AM   #37
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
The bords are stuffed with the exception of a few mechanical parts. There is a bug on the phono board. The negative voltage is breaking down in the Opamp section.
Attached Images
File Type: jpg Nobrainer PCBs stuffed.jpg (116.9 KB, 551 views)
  Reply With Quote
Old 19th June 2012, 07:30 PM   #38
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Holger Barske played a solar panel driven system on the Frickelfest. I contributed with my build of the Nobrainer that draws not more then 50 mA, both channels driven.
I also gave Holger the grand father of the high speed preamp, described on MPP, but unfortunately there was a short in the P-P build and i was too occupied to repair it, so he played a passive preamp. The power amp was a switched mode thing that did not sound fully satisfying. On the other hand i think a solar driven system is a good idea so Holger asked me if i can design a power amp that works on plus-minus 12V and does not draw too much power.
I had a little time today and came up with a possible solution. Some time ago there was a little thread about Diamond-Sziklai Power Buffers. I found a circuit by Lineup that is a further development of a PMA buffer that i like. The only thing i did is lowering the idle to 120mA and re dimensioning the circuit to smaller output transistors and lower voltage. 120mA and around 24,5mV over the output resistors is a good compromise when we want to avoid class-A that is out of the question because of efficiency. We need voltage gain of cause so i added an Opamp. The buffer works open loop here.
Another option is to put the buffer in an inverted loop and add a buffer at the input.
This is a bit more complex but lower in static distortion.
Some time ago i build a headphone amp that way that sounded good.
  Reply With Quote
Old 19th June 2012, 07:35 PM   #39
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
Here is my hand drawing.
Attached Images
File Type: jpg Low Idle Amp.jpg (33.9 KB, 483 views)
  Reply With Quote
Old 19th June 2012, 07:58 PM   #40
diyAudio Member
 
Joachim Gerhard's Avatar
 
Join Date: Mar 2009
The bug in post 37 was solved some time ago so the Nobrainer plus PSU works just fine.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
My first discrete amp danfo098 Solid State 60 30th July 2009 05:40 AM
Best discrete regulator ? ANADIGIT Solid State 1 1st December 2008 02:55 PM
discrete DAC Bernhard Digital Source 6 26th September 2008 12:24 PM
My discrete opamp udip Solid State 51 8th August 2006 07:33 AM
which discrete preamp ? sopapo Solid State 12 13th January 2006 08:11 PM


New To Site? Need Help?

All times are GMT. The time now is 09:28 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2