Need help changing 12V heater to 6V - 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 8th April 2010, 10:34 PM   #1
phrarod is offline phrarod  United States
diyAudio Member
 
Join Date: Aug 2005
Default Need help changing 12V heater to 6V

I want to use a different tube that uses a 6.3V filament. I have a 12.6V supply but the reg is adjustable.

What resistor changes ie values do I need for the resistor divider network that is in there now. It has a 200R and a 2K. Schematic attached.

Much appreciated!
Attached Images
File Type: jpg ls-65-fil-schem-sm.jpg (14.9 KB, 137 views)
  Reply With Quote
Old 8th April 2010, 11:02 PM   #2
tomchr is offline tomchr  United States
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Greater Seattle Area
Quote:
Originally Posted by phrarod View Post
I want to use a different tube that uses a 6.3V filament. I have a 12.6V supply but the reg is adjustable.

What resistor changes ie values do I need for the resistor divider network that is in there now. It has a 200R and a 2K. Schematic attached.
The regulator is an LM317T (made by National Semiconductors and many others). You can calculate the resistors needed for a given output voltage by following the equation on pages 1 and 9 of the LM317 data sheet.

~Tom
  Reply With Quote
Old 8th April 2010, 11:22 PM   #3
phrarod is offline phrarod  United States
diyAudio Member
 
Join Date: Aug 2005
Thanks Tom! My math is horrible but I give it a go since the formula is there. I have values in there as reference for calculation for 12.8V
  Reply With Quote
Old 9th April 2010, 12:02 AM   #4
diyAudio Member
 
Gorgomat's Avatar
 
Join Date: Aug 2009
LM 317 Calculator
  Reply With Quote
Old 9th April 2010, 12:12 AM   #5
Matt BH is offline Matt BH  United Kingdom
diyAudio Member
 
Join Date: Jul 2009
Location: Cheltenham
I dont know what current you need? but be sure you dont run the 317 too hot

Cheers Matt.
  Reply With Quote
Old 9th April 2010, 12:41 AM   #6
phrarod is offline phrarod  United States
diyAudio Member
 
Join Date: Aug 2005
WOW! The calculator is awesome. Looks like R2 or in my case R11 is 810R I get 6.3V

I don't think it will run too hot.
  Reply With Quote
Old 9th April 2010, 01:52 AM   #7
Banned
 
Join Date: Jan 2008
Blog Entries: 2
Quote:
Originally Posted by phrarod View Post
I don't think it will run too hot.
How much current?

If the tube is equivalent, then the current will be ~double that in the original circuit. The voltage dropped across the 317 will be 6.3 volts higher. So the dissipation in the 317 will be ~4 times the original.

Has it got a heatsink? 400% could be too much...

w
  Reply With Quote
Old 9th April 2010, 02:22 AM   #8
phrarod is offline phrarod  United States
diyAudio Member
 
Join Date: Aug 2005
It does have a heat sink. I need to investigate this. Thanks for the reality check on this.
  Reply With Quote
Old 9th April 2010, 04:08 AM   #9
phrarod is offline phrarod  United States
diyAudio Member
 
Join Date: Aug 2005
I was using a 5965 and will be moving to a tube with the following specs:

Uf = 6.3V, If = 350 mA uM = 25 Ia = 10.5 mA S = 6.8 mA/V Pa = 1.5 W

I have two filament supplies. One for each tube.
  Reply With Quote
Old 9th April 2010, 06:22 AM   #10
phrarod is offline phrarod  United States
diyAudio Member
 
Join Date: Aug 2005
One last question. If I do run into heat issues with the reg can I go to a LM335T and have the same voltage divider resistor values?
  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
how to wire 6.3VDC heater on a heater with center tap (12.6V series, 6.3V parallel)? jarthel Tubes / Valves 9 14th April 2012 06:36 PM
12.6v+ vs 6.3v+/- heater supply mountainhick Tubes / Valves 16 28th February 2010 04:41 PM
Again (sorry) what's the biggest 6V heater double rectifier? leadbelly Tubes / Valves 5 9th August 2007 12:24 AM
12v to (6v times 2) legendaryfrog Parts 8 27th October 2006 10:34 PM
Using 6V to power 12V DAC Ian J Digital Source 0 4th January 2004 07:18 PM


New To Site? Need Help?

All times are GMT. The time now is 08:58 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