Adjustable negative voltage supply - 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 26th July 2010, 07:23 PM   #1
diyAudio Member
 
Join Date: Mar 2006
Location: Michigan
Default Adjustable negative voltage supply

Hello everybody,

I am making a High negative voltage supply for a differential stage in a tube amplifier I am constructing. I don't need more than -120v.

I stumbled across this gem http://www.national.com/an/LB/LB-47.pdf

Basically what I want to do is change the LM317 to an LM337. I was thinking the following steps would be needed

1. Switch NPN transistors to PNP
2. Reverse all Diodes
3. Reverse any electrolytic capacitors.

Am I forgetting anything?

thanks
-Moose
  Reply With Quote
Old 27th July 2010, 10:21 AM   #2
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
an isolated supply can have any output voltage, it is effectively floating.
Connect one side of the supply to a reference, let's use Zero Volts = Ground, then the other voltage is referred to that.
If you have an isolated +ve regulator with 120V between the two outputs, then either output can be connected to the reference.

Connect the more -ve output to Zero Volts and you have 0,120V supply
Connect the more +ve output to Zero Volts and you have 0, -120V supply.

This will work just as well as your proposal, without having to worry about whether it might work as modified.
__________________
regards Andrew T.
  Reply With Quote
Old 27th July 2010, 02:51 PM   #3
diyAudio Member
 
Join Date: Mar 2006
Location: Michigan
I was thinking about that as well, Just connect the output to some -1xx voltage and use the regulator backwards? sounds even easier

Thanks
  Reply With Quote
Old 28th July 2010, 11:25 AM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
that's not quite what I said.

Connect one output pole to your voltage reference and the regulator sends the other output pole voltage at it's regulated voltage.

eg. build a 0,+120Vdc regulated supply.

Connect 0V output to Zero Volts and the other output will sit at +120Vdc.

Instead connect +120Vdc output to Zero Volts and the other output will sit at -120Vdc.

There is nothing fitted "backwards".

On the other hand you could have a 0, +60Vdc supply with 0 connected to Zero Volts. The other pole sits at +60Vdc. Now connect the 0 of your 120V supply to the existing +60Vdc and the other output of the 120V supply will sit at +180Vdc (+60V +120V = 180V)
__________________
regards Andrew T.
  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
Adjustable power supply questions rendisha Parts 28 10th June 2013 09:57 AM
Adjustable voltage-mode smps zkaiser Power Supplies 6 3rd December 2010 12:25 PM
adjustable voltage regs compatability KevinLee Parts 1 16th December 2008 07:18 PM
LM385 Adjustable voltage ref. diode as LED bias? mus Tubes / Valves 2 30th March 2007 04:27 AM
Adjustable regulated power supply Ford_V6 Solid State 2 1st April 2003 05:03 PM


New To Site? Need Help?

All times are GMT. The time now is 02:38 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