The simplistic Salas low voltage shunt regulator - Page 520 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 23rd July 2012, 08:14 PM   #5191
euro21 is offline euro21  Hungary
diyAudio Member
 
Join Date: Sep 2004
Location: Budapest
Plot of few 2SK170GR Idss.
Attached Images
File Type: jpg 2SK170 GR IDSS.jpg (63.2 KB, 421 views)
  Reply With Quote
Old 23rd July 2012, 09:31 PM   #5192
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
170GR is giving more drift in this circuit than BL. Better the 245A if with GR.
  Reply With Quote
Old 26th July 2012, 08:15 AM   #5193
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
tried to match 3 sk170GRs and came out with 4.86, 4.88 and 4.94mA. Soldered them back, turned the reg on, adjusted trimmer to 5vdc output and closed the lid of the case. After about 15min I still got 5.20vdc...weird.

then I put BF245A as Q3, adjusted the legs as it's not pin to pin replacement, same with vdc output and closed the lid...after some 10min I got 4.89vdc it'seems that it's affected vice versa by the heat. Anyway I was unlucky again.

Is there any other suggestions? Perhaps if I use two decent BLs with 7-8mA IDSS as was adviced in some other thread + BF245A as Q3 that would stabilize the output vdc?

Accoring to the manual WM8740 DAC should work fine with +-10% of 5vdc, thus maybe it's not so crucial as it is now?
  Reply With Quote
Old 26th July 2012, 08:26 AM   #5194
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Q3 is the crucial component. With BF245A you went off only -0.11V you report. Why not adjust at 5.1V and then let it drift to 5V? Its the LEDs and the Vbe of the BC550 they act in tandem with Q3, and the PPM of the trimmer. Your manual gives 4.5V-5.5V tolerance, in other words why bother for 0.1V?
  Reply With Quote
Old 26th July 2012, 08:31 AM   #5195
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
And... minus drift is safer.
  Reply With Quote
Old 26th July 2012, 11:22 AM   #5196
diyAudio Member
 
Join Date: Nov 2009
Location: UK, Manchester
Quote:
Originally Posted by Salas View Post
... in other words why bother for 0.1V?
indeed, it's pretty negligible in this case. I was just wondering why does it happens (thanks for explanation) and why nobody reported the same bahaviour.

Quote:
Originally Posted by Salas View Post
And... minus drift is safer.
yes, thanks again for the help, Salas, and great reg!
  Reply With Quote
Old 26th July 2012, 12:18 PM   #5197
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
The Leds are diodes, they show negative tempco, a few mV/C each. Its a balance of counteraction with the other semis. At 55C box interior your drift is fine IMHO. This reg isn't designed around a precision voltage reference concept, but around a minimalistic discrete one. We can be very careful about a Jfet type and sample and its zero tempco bias point, the exact drift of the whole system including Vbe & Vgs and the number and type of diodes, Leds etc so to minimize drift, but -0.1V in a hot box it can easily creep in again and its fine for audio purposes IMHO. I am sure all get some drift if they look for it, but you got a hot box interior that others may not. They may be using lower ppm resistors too. Its not a chip to tightly control the spot temperature each semi has anyway, its discrete and biggie with through hole components.
  Reply With Quote
Old 27th July 2012, 01:57 AM   #5198
agussug is offline agussug  Indonesia
diyAudio Member
 
Join Date: Jul 2010
My regulator drift from 11.94 to 11.87 in 10 min. and remain stable after that, as I reported earlier in this thread.

Regards
  Reply With Quote
Old 9th August 2012, 11:19 AM   #5199
kokonut is offline kokonut  Germany
diyAudio Member
 
Join Date: Dec 2010
Location: düsseldorf
Default is this a correct interpretation of Salas 1.0 sslv

I want to use this schematic and this pcb for salas V 1.0 with IRF9610,9530 instead of IRF9240 for low current loads like DAC,Clock,Buffer,Phonopre. is this schematic correct for this applications and the pcb design ok? the pcb is from myself and i tryed to get it small as possible for my small chassis. the salas sslv bib is to big for my application. for dirct use i dont need the sensing feature.

thanks for your attention and help

kokonut
Attached Images
File Type: png sslv_pcb.png (13.8 KB, 252 views)
File Type: png sslv_schematic.png (13.5 KB, 259 views)
  Reply With Quote
Old 9th August 2012, 12:26 PM   #5200
Salas is online now Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Delete R3, R4, change C5 to 47uF electrolytic, build with both C2, C5, R7. About PCB you got to try it and see.
  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



New To Site? Need Help?

All times are GMT. The time now is 12:20 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