SMPS For Tubes - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

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 19th October 2003, 07:52 PM   #11
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Could always burn off the crap from a core (ferrite is ceramic, right?) and glue up a paper bobbin.

I figured these cores would be lossy... seem to remember something like that. But at least it's made to handle DC..

I'll check out some ferrite cores around here and see if I can get at any without breaking them.

Oh, I have a few line filter chokes which look kinda loose, I'll try one of those (with a bit of air gap of course).

The existing cores run a bit warm, but 26AWG is good for about 400mA, and with up near an ampere through it, it's no suprise it's getting warm. But I'll consider core loss...

Tim
__________________
Seven Transistor Labs
Projects and Resources
  Reply With Quote
Old 19th October 2003, 07:58 PM   #12
diyAudio Member
 
smoking-amp's Avatar
 
Join Date: Dec 2001
Location: Hickory, NC
Here's another idea for getting HV from a surplus SMPS. Get two identical supplies and yank the xfmr out of one of them. (well maybe more gently). Remove the rectifier/inductor/cap DC output filter connection to the output xfmr in the other supply. Now connect the loose xfmr in reverse to the xfmr in the power supply unit. (ie. secondary to secondary) Its primary will then produce something like the usual 370V peak voltages originally sourced from the rectified AC power. Unfortunately, this is only a peak voltage output, for 50% PWM duty cycle this can only be used to generate steady 370/2 Volts. But if the primary was of the center tapped type, can get back up to full 370 V with a full wave bridge rectifier. The output DC filtering components will as usual have to be changed to accomodate the new higher voltage, as well as the controller voltage feedback resistive divider. This approach may cause some feedback stablility problem since the distributed xfmr capacitance and leakage reactance are doubled. So some fixing of the feedback loop gain rolloff may be necessary like with the HV voltage multiplier idea. But will require a far less drastic cut in loop bandwidth than with the voltage multiplier approach, which slows response time to over several clock cycles.
__________________
I want a Huvr-Board!!
  Reply With Quote
Old 19th October 2003, 11:05 PM   #13
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Quote:
Originally posted by smoking-amp
SG3524 and related models are like the 6L6 or uA741 of PWM controller design. Good chip, a little dated.
If you are going to invest the time, consider some of the slew controlled switcher chips and gate drivers from Linear Tech. Of course, they cost about 10X what a '3524 goes for, but the effect should be quite noiseless.
  Reply With Quote
Old 21st October 2003, 06:02 AM   #14
subwo1 is offline subwo1  United States
diyAudio Member
 
subwo1's Avatar
 
Join Date: Jan 2002
Location: North American Continent
Would you be adverse to using a CD40106 or 74C14 hex Schmitt gate IC? They are simple in my opinion--more convient than discrete parts but rugged and easy to understand in regard to circuit function. I design my switchers with them as the oscillator and controller.
__________________
USMPS
http://groups.yahoo.com/group/switchmode/
  Reply With Quote
Old 21st October 2003, 07:15 AM   #15
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Mmm, simple logic doesn't sound all that bad. Just keep flip-flops away from me, or I'll flip-flop.

And yes I've also thought of the venerable 555, I'll do some screwin' around with pin 5 on that thing some time and see what comes up.

Tim
__________________
Seven Transistor Labs
Projects and Resources
  Reply With Quote
Old 21st October 2003, 11:31 AM   #16
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Quote:
Originally posted by subwo1
Would you be adverse to using a CD40106 or 74C14 hex Schmitt gate IC? They are simple in my opinion--more convient than discrete parts but rugged and easy to understand in regard to circuit function. I design my switchers with them as the oscillator and controller.
if you are going to use discretes and some kind of push pull converter (Steve Bench's web page?) make absolutely sure that the devices aren't on for more than 50%
  Reply With Quote
Old 21st October 2003, 04:29 PM   #17
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Yes indeedy, that could get interesting..

Tim
__________________
Seven Transistor Labs
Projects and Resources
  Reply With Quote
Old 21st October 2003, 05:13 PM   #18
diyAudio Member
 
Claude Abraham's Avatar
 
Join Date: Apr 2003
Location: NE Ohio
Default smps recommendations

The discrete route has its limitations. Trying to vector board this circuit could introduce problems with noise emission and pickup, as well as point to point wiring inductance. For switching, MOSFETs should be used for lower loss. If the discrete approach doesn't give you the desired results, do consider an integrated switcher IC, such as the TOP Switch family from Power Integrations (www.powerint.com). The TOP247, 248, or 249 should do the job. Included are application notes, and an Excel spreadsheet program to help design the flyback transformer. At 400 volts, 100 milliamps, or 40 watts, the flyback converter is a good choice. You can use one transformer with dual secondaries to get both the plus and minus output voltages. I hope this helps.
__________________
"We wish to reach the moon, not because it is easy, but because it is hard."
John F. Kennedy, 1917-1963, US President
  Reply With Quote
Old 21st October 2003, 07:03 PM   #19
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Default Re: smps recommendations

Quote:
Originally posted by Claude Abraham
The discrete route has its limitations. Trying to vector board this circuit could introduce problems with noise emission and pickup, as well as point to point wiring inductance. For switching, MOSFETs should be used for lower loss. If the discrete approach doesn't give you the desired results, do consider an integrated switcher IC, such as the TOP Switch family from Power Integrations (www.powerint.com). The TOP247, 248, or 249 should do the job. Included are application notes, and an Excel spreadsheet program to help design the flyback transformer. At 400 volts, 100 milliamps, or 40 watts, the flyback converter is a good choice. You can use one transformer with dual secondaries to get both the plus and minus output voltages. I hope this helps.
I hope no one seriously considers a flyback SMPS for audio purposes, just too noisy.
  Reply With Quote
Old 21st October 2003, 07:11 PM   #20
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
What is this noise everyone's talking about anyway? As-is it operates above the audio range, something easily filtered. After that, some hefty electrolytics could be used anyway, to add general stiffness to the line.

I don't see any problems a bit of shielding, L's and C's can't fix.

Tim
__________________
Seven Transistor Labs
Projects and Resources
  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
Tube Noob! need help with tubes lots of tubes therapy_fan Tubes / Valves 15 29th January 2009 09:01 PM
WTT: Various tubes for 6CA4/EZ81 rectifier tubes GordonW Swap Meet 4 27th August 2008 12:37 AM
SMPS and tubes Vuokko Tubes / Valves 2 1st March 2007 07:59 PM


New To Site? Need Help?

All times are GMT. The time now is 05:43 PM.


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