Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki 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

Regulated heater reference
Regulated heater reference
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 March 2007, 01:30 AM   #1
Quince is offline Quince
Banned
 
Join Date: Mar 2007
Default Regulated heater reference

I've this regulator for the heaters of four EL34 tubes. The reason of two regulators on top of one another is the lower portion of voltage lost in rectifiers than if I had only 6 V for output.

My question is, since the cathodes sit around -350 V, how do I reference the heaters to that so that the heater to cathode potential rating is not exceeded, without frying the regulator's low voltage components? The thing is, a relay delays the HV so when the heaters come on initially, there's no voltage applied to the tube's cathode or plate, and the HV supply is not even on (the relay is before the rectifiers since relays have much lower DC ratings).

Click the image to open in full size.
  Reply With Quote
Old 23rd March 2007, 02:21 AM   #2
SY is offline SY  United States
On Hiatus
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Regulated heater reference
If you draw an actual schematic, it will be easier to answer your question. I got a headache looking at that! You needn't throw in every wire resistance.
__________________
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
  Reply With Quote
Old 23rd March 2007, 03:18 AM   #3
Wavebourn is offline Wavebourn  United States
Designer & Technologist
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Regulated heater reference
I would connect filaments in series instead of using 2 regulators. Also, I don't understand why do you need a regulated supply for filaments of power tubes.

__________________
Nothing in the universe is perfect. The ideal things are the ones that are most optimal. Optimization criteria, what matters. When I hear "No Compromise Design", I want to take a sledgehammer and test how impact-proof it is.
  Reply With Quote
Old 23rd March 2007, 03:24 AM   #4
FastEddy is offline FastEddy  United States
diyAudio Member
 
FastEddy's Avatar
 
Join Date: Jun 2006
Location: North Californie
" ... I don't understand why do you need a regulated supply for filaments of power tubes. ..."

'cause most heaters have an AC source, which injects an added noise component into the tube where the action is ... sometimes this AC noise can leak into the audio amplification resulting in, well, extra noise on the audio sgnal ... Sy?
  Reply With Quote
Old 23rd March 2007, 04:05 AM   #5
Quince is offline Quince
Banned
 
Join Date: Mar 2007
I don't think the details matter. Here's an abstracted version.

http://img482.imageshack.us/img482/8840/hregqb9.png
  Reply With Quote
Old 23rd March 2007, 04:05 AM   #6
Quince is offline Quince
Banned
 
Join Date: Mar 2007
The matching of filaments is not that great, so in series doesn't work well. Now, the mismatch would seem to be just as bad in parallel except for the fact that filaments are not simple resistors but their resistance varies with temperature. For EL34 tubes I find in parallel works better. However, I can't have all four in parallel since then I get twice the rectifier loss and I don't have enough voltage overhead with this transformer.

In any case, this still doesn't address my original question.
  Reply With Quote
Old 23rd March 2007, 04:05 AM   #7
Quince is offline Quince
Banned
 
Join Date: Mar 2007
These tubes are driving electrostatic headphones, and I want the lowest possible noise floor. I've even shielded the power supply separately from the amp.
  Reply With Quote
Old 23rd March 2007, 10:11 AM   #8
SY is offline SY  United States
On Hiatus
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Regulated heater reference
Quote:
Originally posted by Quince
I don't think the details matter. Here's an abstracted version.

http://img482.imageshack.us/img482/8840/hregqb9.png
The details absolutely do matter. There are two considerations- noise injection and heater-to-cathode ratings. Without an actual schematic, it's difficult-to-impossible to lay out the correct way of setting up the heaters or to determine how many heater supplies you actually need.

FE: Generally, you don't have to regulate power tube heaters; noise is usually not an issue and when it is, it's almost always common mode, which takes a different means to prevent. The exception is direct-coupled circuits, where any drift of output tubes off their nominal operating points can fry something.
__________________
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
  Reply With Quote
Old 23rd March 2007, 10:48 AM   #9
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Regulated heater reference
Just use a common mode choke.
  Reply With Quote

Reply


Regulated heater referenceHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Regulated Heater test supply ThSpeakerDude88 Power Supplies 3 5th December 2007 09:40 PM
Heater reference Nixie Tubes / Valves 3 2nd July 2006 03:58 AM
regulated DC heater supply jarthel Tubes / Valves 30 29th May 2006 12:19 AM
Regulated Heater Supply Kashmire Tubes / Valves 6 4th January 2004 02:23 AM


New To Site? Need Help?

All times are GMT. The time now is 03:19 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki