Regulated Heater Supply
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 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
Kashmire
diyAudio Member

Join Date: Dec 2003
Location: Midwest
Regulated Heater Supply

I've been reading some discussion about using DC and/or regulated heater supplies. Using DC for heaters is tricky because normal 6.3VAC transformers sometimes won't work.

I have attached a schematic below and indicate what transformer voltage is required.

The heater uses 6.3V, but this schematic features current regulation. For example, assume the tube heater requires 420mA.

The voltage regulator maintains 1.25V across R. Therefore, to get 420mA over a 1.25V drop, 1.25/0.420 = 3 Ohms.

The voltage regulator also drops voltage. Depending on which type you choose, this can be from 3 to 4.5V. The LM317 is on the high end. LT1083/84/85/86 may be a bit lower. I'll contact Linear Technology for exact numbers. If you don't allow enough voltage to cross the regulator, it will stop working.

The diode bridge also drops voltage. A normal diode at full load will drop 0.7V. Since the power goes through 2 diodes, expect 1.4V to be lost.

Add these voltages: 6.3 (heater) + 1.25 (resistor) + 4.5 (regulator) + 1.4 (diodes) = 13.45.

In the end, the circuit requires about 13.45VAC peak-to-peak, therefore about 9.5VAC rms. Hammond makes some 10V 1A transformers (164G10) for \$11 from Digikey that could power two of these tubes. Each tube needs its own current regulator, otherwise, one tube could be slammed with too much current!

The diode pictured is for reverse-potential protection. The capacitors could be anything, but I'd recommend at least a 6800uF can on the input.

The resistor will dissipate 0.5W and the regulator will dissipate 1.9W. Heatsink appropriately!
Attached Images
 heatersupply.jpg (19.2 KB, 928 views)

 4th January 2004, 12:45 AM #2 Saurav diyAudio Member   Join Date: Sep 2002 Location: Oregon, USA I built this for my 2A3 amp, with Hammond 6.3V transformers, individually heatsinked (heatsunk?) MBR735 high current Schottky diodes and an LT1085. It sounded pretty good, but got really hot under my already crowded chassis, so I eventually went back to AC filaments. As you pointed out, using higher voltage transformers will allow you to produce higher regulated voltages (that's a pretty redundant statement ) If you're planning for this from the start and take care of ventilation, this can work well. I have almost all of the parts lying around for a 2.5V/2.5A current regulated supply, in case anyone's interested (shameless plug ) http://www.diyaudio.com/forums/showt...threadid=21409
 4th January 2004, 12:47 AM #3 EC8010   diyAudio Moderator Emeritus     Join Date: Jan 2003 Location: Near London. UK Yes, but what's the question? BTW. You have shown that current regulated supplies only make sense with a series string of valves requiring a total voltage of more than 6.3V... __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
fdegrove
diyAudio Senior Member

Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
 BTW. You have shown that current regulated supplies only make sense with a series string of valves requiring a total voltage of more than 6.3V...
You don't expect anyone to actually think or, do you???

...You don't....I know..........

Oh well....Maybe one day.....
__________________
Frank

 4th January 2004, 01:32 AM #5 EC8010   diyAudio Moderator Emeritus     Join Date: Jan 2003 Location: Near London. UK Look on the bright side... Actually, I do! And if not, I hope to provoke thought (although I always prefer to think it was going to happen anyway). __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
fdegrove
diyAudio Senior Member

Join Date: Aug 2002
Location: Belgium
Hi,

Quote:
 Actually, I do! And if not, I hope to provoke thought (although I always prefer to think it was going to happen anyway).
Good...I'm not alone anymore then...

I provoked thought in the DIY Turntable thread and almost got banned for life, how hard is it to think for oneself?

Is it Mc Donalds, Coke, Pepsi or what?...
Were'all just sheep in a heard, aren't we?

Cheers,
__________________
Frank

 4th January 2004, 03:23 AM #7 Kashmire   diyAudio Member   Join Date: Dec 2003 Location: Midwest The circuit pictured, EC8010, is a 420mA current regulator capable of delivering regulated output up to about 6.5VDC. It is appropriate for a single tube heater. This circuit will control the current while the heater is cold, thereby eliminating the turn-on surge. If the voltage of this circuit is increased, multiple heaters could run in series. This circuit is not appropriate for heaters in parallel. Other currents can be obtained by varying the value of R. The purpose of this example was to illustrate that running heaters with DC or regulated DC may not always be as straightforward as placing a diode bridge onto an ordinary filament transformer.

 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 Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Aussie Amplifiers         CSS         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post eranrund Tubes / Valves 10 30th December 2008 05:58 PM ThSpeakerDude88 Power Supplies 3 5th December 2007 10:40 PM Quince Tubes / Valves 8 23rd March 2007 11:48 AM jarthel Tubes / Valves 30 29th May 2006 01:19 AM

 New To Site? Need Help?

All times are GMT. The time now is 07:12 PM.

 Home - Contact Us - Advertise - Rules - diyAudio Store - Sponsors - Privacy Statement - Terms of Service - Top - Opt-out policy

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki