Low dropout 6.3v - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

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
Thread Tools Search this Thread
Old 27th February 2011, 09:17 AM   #1
diyAudio Member
richwalters's Avatar
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Default Low dropout 6.3v

The circuit enclosed is one of my modified junk box designs from my prime analogue haydays of 1966......the advent of Bob Widlar and the uA709,741 etc. It caused a stir.

Notice the "jockey" soft rectifier doubler incorporated within a standard full wave rect to supply that little bit of extra voltage headroom for the op amp supply, otherwise the output cannot swing enough to supply the extra to accomodate the mosfet g/s drop voltage..only a mA or so is required.-
This little technique can greatly reduce pass transistor dissipation.
The basic current limiter softens current surges with cold tungsten resistance, so often ignored, also an ultra low Rds mosfet is an obvious candidate. As mentioned for the HV variant, the current layout is important for low noise.

As with these circuits, alot of variations, with the other half of the unused 1458 one can configure to further reduce the Vdrop of the 0.22R current limit to performance approaching the lowest dropout ic regulators.
Breadboard and simulate it.

Attached Images
File Type: jpg New 8659 Isolated 6.3V.jpg (35.6 KB, 100 views)
  Reply With Quote
Old 27th February 2011, 09:50 AM   #2
diyAudio Member
richwalters's Avatar
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Another advantage of using an op amp is the excellent supply ripple rejection they provide (study data sheets)., so in the example shown a "rough" supply performs superbly.
  Reply With Quote


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
Troubleshooting channel dropout Jim W Tubes / Valves 11 7th January 2016 02:46 AM
Volume dropout matt_moose Solid State 5 11th February 2010 06:27 PM
530V low-ish dropout regulator? dsavitsk Tubes / Valves 5 10th December 2009 03:02 AM
If I need to low down a +58VDC/1.5A straigth down to 3.3V goldkenn Digital Source 3 20th September 2007 11:56 AM
sub dropout n00bie Subwoofers 6 23rd June 2005 07:23 PM

New To Site? Need Help?

All times are GMT. The time now is 03:08 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2