300b filament - 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 23rd October 2010, 09:53 PM   #1
diyAudio Member
 
Join Date: Oct 2009
Default 300b filament

could rectify the filaments 300b with the voltage of 5 volts ac transformer, how I can do? Consumes more amps the transformer,
made with the 6SN7 and warmed over, someone can help me, thanks
  Reply With Quote
Old 25th October 2010, 08:27 PM   #2
tomchr is offline tomchr  United States
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Greater Seattle Area
I'm not sure what you're trying to do here. Are you trying to build a DC supply to run the filament of a 300B? If that's the case, then I suggest looking at an LM317 voltage regulator IC. Or you can follow what I did in this thread.

You will need a rectified DC voltage of at least 7.5 V at the input of the LM317 (or LMZ12002). Use a 9 VAC transformer that can supply the needed current (1.5 A per 300B). You'll need a diode bridge that can handle the current with plenty of margin - KBPC2504 would be practically indestructible in your application. Then add a 10000 uF cap on the output of the diode bridge. The cap should be able to handle at least 25 V.

The LM317 will dissipate up to 10 W so it will need a fairly big heat sink.

For the 6SN7 filaments, you can go with AC -- or if you insist on using DC, you can do the same as above. However, as the 6SN7 needs 6.3 V, you'll need a transformer that can supply 12 VAC. The feedback resistors on the LM317 will be different than those used for 5 V. There's an equation in the data sheet for calculating those resistors.

Does this help?

~Tom
  Reply With Quote
Old 25th October 2010, 10:00 PM   #3
Account disabled at member's request
 
Join Date: Apr 2009
The 10000 uF cap should be of really good quality because of the continuous current.

Pieter
  Reply With Quote
Old 26th October 2010, 12:52 AM   #4
tomchr is offline tomchr  United States
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Greater Seattle Area
Yeah, the cap should be able to handle the ripple current. Low ESR is a plus. I'd also put a polypropylene cap, 100 nF ~ 1 uF in parallel with the big one for better performance at RF. The LM317 (and LMZ12002) requires an input cap for stability anyway.

~Tom
  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
300B SwitchMode filament supply tomchr Tubes / Valves 35 23rd January 2013 05:21 PM
Current regulation for filament of say a 300B Bas Horneman Tubes / Valves 10 3rd September 2008 10:32 PM
One 300B filament supply for stereo? dshortt9 Tubes / Valves 1 7th September 2007 08:14 PM
300B Filament Voltage Range dsavitsk Tubes / Valves 4 14th October 2005 07:07 PM
300b filament q, yes another one. gtmcgar1 Tubes / Valves 7 12th July 2005 08:31 AM


New To Site? Need Help?

All times are GMT. The time now is 12:26 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