Regulator - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, 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 25th September 2007, 12:30 PM   #1
diyAudio Member
 
Join Date: Jul 2001
Default Regulator

I realise this kind of question is asked a lot, but i've gone through all the posts and i don't seem to be able to figure it out. I'm using the circuit as attached, with the sense lines directly connected to the output for now. This circuit is working perfectly with +12V, but i also want +5V so i swapped out the 6.9V LM329 for the LM336 2.5V and used 1/1 for the divider network on the -ve side of the opamp. This according to theory should give me 5V. However the reference seems to breakdown much lower and therefore give me around 3V output, which i can't explain.

I've tried using an opa277 because i read somewhere that the common mode voltage was important but it did exactly the same. I've even tried putting the lm329 6.9V in and fitting a resistor across C16 to drop the reference, but with similar results. Its like there is a minimum voltage of the circuit, but i don't understand why - pass transistor maybe?

Is there something fundamental i'm missing?

Sorry if this has been answered before but i'm banging my head trying to work it out.

Thanks
Attached Images
File Type: gif regulator.gif (6.8 KB, 251 views)
  Reply With Quote
Old 25th September 2007, 04:02 PM   #2
diyAudio Member
 
Join Date: Jul 2001
I took out R24 and used a second supply instead of the zener. It works fine, which i assume means that the pass transistor and opamp used are fine. Can anyone see what i'm doing wrong with the zener?

Thanks
  Reply With Quote
Old 25th September 2007, 04:14 PM   #3
diyAudio Member
 
Join Date: Jul 2001
Default Obvious

OK that's obvious really, not enough reverse current on zener, dropped r26 to 2k7, did the job. Sorry to bother people!

Andrew
  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
HV Regulator habsrock93 Tubes / Valves 3 21st October 2008 08:15 AM
Zener regulator with "integrated" pre-regulator 00940 Power Supplies 17 22nd July 2008 06:11 PM
Lithos regulator - A new super regulator? peranders Parts 7 8th May 2008 03:01 PM


New To Site? Need Help?

All times are GMT. The time now is 12:32 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