12V AC to 6.3v DC simple supply for idiots - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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
Reply
 
Thread Tools Search this Thread
Old 13th September 2009, 03:09 AM   #1
diyAudio Member
 
Join Date: Jan 2002
Location: Canberra, Australia
Default 12V AC to 6.3v DC simple supply for idiots

Originally I was planning to slightly under heat the tubes in my 6CG7 and EL84 PP amp using a 12v AC supply, but I've been advised that I'd be much better off using a 6.3v DC supply instead.

Given that throwing another 12v AC toroid into the chassis is no drama, has anyone got a childs play circuit for giving a smooth 6.3v DC supply capable of feeding the heaters of 4EL84's and 2 6CG7's.

Rather have it regulated with a bit of spare current capacity so that a change in draw won't cause the voltage to droop than do it unregulated with a Pi filter.

Looking for cheap simple and pretty idiot proof.

An old HiFi World DIY supplement for their phono stage uses a bridge rectifier feeding a 4700uF cap into a 78S05 regulator with a pair of 1N4001's under its ground terminal outputting into a 100u cap.

This arrangement is only feeding a trio of ECC83's and a pair of 6922.s though.
  Reply With Quote
Old 13th September 2009, 03:13 AM   #2
diyAudio Member
 
aardvarkash10's Avatar
 
Join Date: Mar 2007
Location: Auckland, NZ
check out the application notes for the LM3705. They show a current enhanced option using a basic transistor (can't remember which) to carry the main current.
__________________
"Folks, you can't prove truthiness with information. You prove truthiness with more truthiness. In a process known as truthinessiness." - Stephen Colbert, The Colbert Report
  Reply With Quote
Old 13th September 2009, 03:36 AM   #3
diyAudio Member
 
SpreadSpectrum's Avatar
 
Join Date: Nov 2007
There is an NJR 2396 6.3V fixed regulator that Mouser sells if you want something simpler. Current capability is not a problem if you split the load and use several of them, running them off of the same filter cap.
  Reply With Quote
Old 13th September 2009, 04:08 AM   #4
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Use 5.6V D5 for 6.3V

http://wavebourn.com/forum/download.php?id=116&f=7
  Reply With Quote
Old 13th September 2009, 01:13 PM   #5
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
Quote:
Originally Posted by DrewP View Post

Rather have it regulated with a bit of spare current capacity so that a change in draw won't cause the voltage to droop than do it unregulated with a Pi filter.

Looking for cheap simple and pretty idiot proof.
hey-Hey!!!,
The heaters are not going to change load demand. I'd suggest a full bridge and an LC-RC filter. You won't need much inductance, and 16V caps are available in low-esr in 15,000 uF about the size of my thumb.
cheers,
Douglas
__________________
the Tnuctipun will return
  Reply With Quote
Old 13th September 2009, 04:37 PM   #6
diyAudio Member
 
Join Date: Feb 2008
You can use a CRC filter to make 12,6 volt and put two tubes in series.

EDIT:

12AC -> Bridge -> C (10000uf) -> R (adjust this one so you get 12,6VDC, use ohm's law) C- (10000uf) to one of the heater pins of a tube, then from the other heater pin to the heater pin of an other tube and then from the heater pin left to ground.

I'm a newbie myself so correct me if I''m wrong.

Last edited by serph1nia; 13th September 2009 at 04:41 PM.
  Reply With Quote
Old 13th September 2009, 08:04 PM   #7
diyAudio Member
 
Gorgomat's Avatar
 
Join Date: Aug 2009
12V AC - bridge rectifier - 4700F 16-25V capacitor - 100nF 63V capacitor - LM317 regulator - 2k resistor adjust-output - 10k variable resistor adjust-ground.
  Reply With Quote
Old 13th September 2009, 09:25 PM   #8
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
I use a large capacitor, dropper resistor and a zener.
  Reply With Quote
Old 13th September 2009, 09:48 PM   #9
pointy is offline pointy  United Kingdom
diyAudio Member
 
pointy's Avatar
 
Join Date: Mar 2009
Bandsnatcher...............as far as I understand you will get some change due to electron emission in times of higher usage

something to do with cooling via electron emission

but don't ask me about it too much as it's just something I have heard of.
  Reply With Quote
Old 13th September 2009, 10:39 PM   #10
pointy is offline pointy  United Kingdom
diyAudio Member
 
pointy's Avatar
 
Join Date: Mar 2009
As a side thought could this effect be the reason why 2a3 valve like to go for a walk in usage?
  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
idiots guide to impedance + spdif measurement woodturner-fran Digital Line Level 7 20th October 2008 07:04 PM
Simple DC Heater Supply d1camero Tubes / Valves 9 19th October 2007 11:33 PM
Idiots question on resistors. Wella Tubes / Valves 3 8th July 2003 12:49 PM


New To Site? Need Help?

All times are GMT. The time now is 03:26 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