Diode for DC heater - 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 31st December 2006, 12:56 AM   #1
diyAudio Member
 
dsavitsk's Avatar
 
Join Date: Jan 2005
Location: Hartford
Default Diode for DC heater

I am looking for diodes to convert an AC heater to a DC one. The current draw is ~2A and the winding is 6.3VAC, so something with minimal voltage drop would be good. Suggestions? With an old trabsformer, I just grounded the center tap and all was well, but I got a new transformer, and this is not working.

Also, if anyone has a favorite circuit for doing this that would be appreciated. I figured I'd use CRC with a couple of 10KuF caps unless someone has a better idea.
  Reply With Quote
Old 31st December 2006, 01:06 AM   #2
Sheldon is offline Sheldon  United States
diyAudio Member
 
Join Date: Dec 2003
Location: San Diego
I've used 1N5821 with good results. Also 6.3V and about 1.8 amps.

Sheldon
  Reply With Quote
Old 31st December 2006, 02:07 AM   #3
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi dsavitsk,
Hum problems? Bias your heater line up to 30 ~ 50 VDC above ground. Bypass the heaters to ground when doing this.

This eliminates any high frequency pickup from tring to rectify and filter your heater. The transformer should run cooler than rectifying the heater line also.

-Chris
  Reply With Quote
Old 31st December 2006, 05:08 AM   #4
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
I have lot of 1N5822 barrier Shottky diodes for such purposes.

Click the image to open in full size.

__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 1st January 2007, 04:10 PM   #5
Sheldon is offline Sheldon  United States
diyAudio Member
 
Join Date: Dec 2003
Location: San Diego
I'd like to try this one for a SS amp project (idle current around 1 amp) and wouldn't have a HT supply. Got a version of that which could run with just the low voltage transformer? Maybe a doubler for the bias supply? Or does the required impedance at R1 have to be too high to allow a lower voltage?

Sheldon
  Reply With Quote
Old 1st January 2007, 04:29 PM   #6
poobah is offline poobah  United States
diyAudio Member
 
poobah's Avatar
 
Join Date: Nov 2005
Use PSUDII and run a sim on your proposed DC heater circuit... pay close attention to the resistance of the supply winding. You will find that it is very difficult to get 6.3VDC from an 6.3VAC winding... you need a HUGE cap.

Also, you are trading an innocent sine wave in your heaters for a spectral nightmare... high frequency stuff... from Schottkys especially. The capacitance from filament to cathode begins to look like an open door at these frequencies.

Don't get me wrong... I'm all for DC heaters. I just think you need to start with at least an 8-9 VAC winding first. Using 6.3 VAC is on the hairy edge of praticality at best.



  Reply With Quote
Old 1st January 2007, 05:19 PM   #7
anatech is offline anatech  Canada
diyAudio Moderator
 
anatech's Avatar
 
Join Date: Jun 2004
Location: Georgetown, On
Hi Poobah,
I'm very glad to see you around. Happy New Year dude!

This is what I've been trying to say all along. I'll add that I used to like DC heaters, but I've seen the light an I now think AC is the best way to go with the possilbe exception of low level stages.

-Chris
  Reply With Quote
Old 1st January 2007, 05:37 PM   #8
poobah is offline poobah  United States
diyAudio Member
 
poobah's Avatar
 
Join Date: Nov 2005
Hey Chris!

Taking the day off... feel like stirring the pot a bit here!

And happy New Year to you as well... and everyone else for that matter!

  Reply With Quote
Old 1st January 2007, 09:41 PM   #9
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Poobah, you are right from theoretical point of view about spectral differences, but my amps are deadly quiet.

Sheldon, R1 to B+ is a simple kind of a current source, you may use CCS from doubled low voltage: you need more than output voltage + 6V + ripples + drop needed for CCS to work well. In most cases you will get it.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 2nd January 2007, 01:16 AM   #10
poobah is offline poobah  United States
diyAudio Member
 
poobah's Avatar
 
Join Date: Nov 2005
Wave,

RIGHT, in the case of full blown regulater, as you've shown. I am just thinking strictly along the lines of plain bridge/RC PSU.

  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
New DHT heater Guido Tent Tubes / Valves 680 31st March 2014 06:20 PM
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
diode bridge - 10000uF cap - diode tube - small cap - HV+ engels Tubes / Valves 5 29th January 2008 11:16 PM
hybrid power supply: diode bridge into diode tube engels Tubes / Valves 8 24th September 2007 10:18 AM


New To Site? Need Help?

All times are GMT. The time now is 07:34 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