50V to +/-15 - Best solution? - 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 3rd March 2013, 07:04 AM   #1
gruni is offline gruni  Germany
diyAudio Member
 
Join Date: Feb 2008
Default 50V to +/-15 - Best solution?

Hi everybody!

I'm repairing an old Lab Power Supply right now. It used to have some weird current sourcing/sinking used in the power supply. I already completely "modernized" the control circuit using JFET current sources etc. so my design only needs +/-15V supply. But i want to keep the original transformer that puts out a single 50V supply. So my question is: what is the best solution to convert 50V to +/-15V? I already thought of two zeners and a resistor, two cascaded 7815 (altough there would be a problem of too high input voltage) or regulation to 30V and using a rail splitter… What do you think is the best? Or is there something better?

Thanks in advance!
  Reply With Quote
Old 3rd March 2013, 07:25 AM   #2
MarianB is offline MarianB  Romania
diyAudio Member
 
MarianB's Avatar
 
Join Date: Jul 2011
Location: Romania
Send a message via Yahoo to MarianB
How much current is needed for that +/-15V? Does the transformer has an 50Vac output or those 50V are after rectifyer and filter cap?
__________________
Trance Session Live by Dj Marik
  Reply With Quote
Old 3rd March 2013, 08:32 AM   #3
gruni is offline gruni  Germany
diyAudio Member
 
Join Date: Feb 2008
50V after filter cap. The +/-15V rails have to supply power to four opamps (TL074) so i think no more than 100mA are needed.
  Reply With Quote
Old 3rd March 2013, 08:36 AM   #4
MarianB is offline MarianB  Romania
diyAudio Member
 
MarianB's Avatar
 
Join Date: Jul 2011
Location: Romania
Send a message via Yahoo to MarianB
Ok then, you can go either with a floating ground or with voltage doubler, witch one seams more to your liking?
__________________
Trance Session Live by Dj Marik
  Reply With Quote
Old 3rd March 2013, 09:09 AM   #5
diyAudio Member
 
payloadde's Avatar
 
Join Date: Mar 2008
similar discussions here:
How to split single 40v into +/-15v ?

and here:
+/-15vdc 7815, 7915 Power supply

doubler is technically O.K. and probably best, but since you already have a high voltage it doesn't seem reasonable to go to 100v first ...

QUAD used a capacitive splitter w/o doubler in their 606 amp to obtain +/-V and virtual gnd from single DC
— Why not buy Keith Snook a BEER —
note T15 / T16 device to keep balance
__________________
Judge: This court appreciates that you invented physics, Mr.Newton, but unfortunately you can't have a patent on it.
  Reply With Quote
Old 3rd March 2013, 09:14 AM   #6
gruni is offline gruni  Germany
diyAudio Member
 
Join Date: Feb 2008
I read those threads but thats not exactly what i'm searching for. The problem that bugs me most is the quite high voltage from the transformer. If i had a 15 to 20V winding, i would just use the voltage doubler design seen everywhere. But 50V is too high for feeding 78XX regulators. So i dont think a voltage doubler would make sense in this case. I think the most desireable solution is to use two 15V zeners and a resistor? What do you think?
  Reply With Quote
Old 3rd March 2013, 10:17 AM   #7
MarianB is offline MarianB  Romania
diyAudio Member
 
MarianB's Avatar
 
Join Date: Jul 2011
Location: Romania
Send a message via Yahoo to MarianB
How do you intend to split a supply with 2 zenners?
__________________
Trance Session Live by Dj Marik
  Reply With Quote
Old 3rd March 2013, 10:19 AM   #8
Elvee is online now Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
A dual-output capacitive supply with 15V zeners seems like the most reasonable solution.
That won't waste too much power.
__________________
. .Circlophone your life !!!! . .
♫♪ My little cheap Circlophone© ♫♪
  Reply With Quote
Old 3rd March 2013, 10:37 AM   #9
MarianB is offline MarianB  Romania
diyAudio Member
 
MarianB's Avatar
 
Join Date: Jul 2011
Location: Romania
Send a message via Yahoo to MarianB
I am not a verry big fan of the virtual ground ideea, it might create problems when connected to other fix grounded circuits... i think voltage doubler would be better, 50Vdc means about 35Vac from the power transformer, and with voltage doubler about +/-50Vdc, a zenner diode each rail helped by a BJT would do just nicely.
__________________
Trance Session Live by Dj Marik
  Reply With Quote
Old 3rd March 2013, 11:14 AM   #10
diyAudio Member
 
Join Date: Jun 2011
Quote:
Originally Posted by MarianB View Post
I am not a verry big fan of the virtual ground ideea, it might create problems when connected to other fix grounded circuits...
Why?
He has a transformer in there...
Its still floating isnt it?
  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
Power Supply -50V gnd +50V RipX Power Supplies 31 24th June 2013 02:52 PM
Antek AN-5450 500VA 50v-0-50v, 18v , 12v Therum Swap Meet 3 19th July 2011 01:07 PM
WTB: BGN 4,7uf 50v, 10uf 50v & 22uf 16v Pocoyo Swap Meet 1 16th September 2010 02:09 AM
Looking for a ~40-300Hz Horn solution with a 15" Driver Bass-Depth Multi-Way 20 1st April 2006 04:19 PM


New To Site? Need Help?

All times are GMT. The time now is 12:54 PM.


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