Regulated Power supplies - Page 4 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 27th August 2002, 03:51 PM   #31
diyAudio Member
 
Join Date: Jan 2001
Location: Scandinavia
Default Instead of throwing away caps

One of the reasons why REALLY big transformers are needed in high-end equipment is the short conduction angle.

Try using a series resistor to increase the conduction angle. This can be done at transformer OR between banks. I would try a small bank followed by an RC large bank.

Petter
  Reply With Quote
Old 27th August 2002, 06:58 PM   #32
diyAudio Member
 
chris ma's Avatar
 
Join Date: Sep 2001
Location: Pickering, Canada
Default series resistor?

Peter,

Can you specify some RC values and component layout please. Are you suggesting there is no need to reduce the capacitance of my PSU?

Quote:
Try using a series resistor to increase the conduction angle. This can be done at transformer OR between banks. I would try a small bank followed by an RC large bank.
  Reply With Quote
Old 27th August 2002, 07:59 PM   #33
diyAudio Member
 
traderbam's Avatar
 
Join Date: Jan 2002
Location: Earth
Using a transformer/rectifier/cap method is one of the crudest ways to get dc from ac that exists. It is like trying to levitate your body by being continually kicked up your backside. Some decades ago choke regulators were fashionable. I suppose the economics of silicon caused the demise of the choke. Choke regulators smooth the rectified current pulses whilst conserving energy (a resistor shunt wastes power). The disadvantage is cost and space and a more complicated design equation.
BAM
  Reply With Quote
Old 27th August 2002, 10:13 PM   #34
ALW is offline ALW  United Kingdom
diyAudio Member
 
Join Date: Jun 2001
Location: UK
Default Hold on, part II

I've found that adding series resistors is detrimental too, although I've not done significant experiments.

There was an obvious reduction in noise, but the sound was more than a little dull and unexciting to listen to.

Yaaawn...


I have a little theory (that I'm keeping to myself at present ) that relates capacitor size to transformer parameters.

It seems to work for all the designs in which I've tried it, but finding optimal capacitor values in PSU's gets expensive.

I've one to build soon and will be trying caps either side of my calculated value - if it works I may reveal more. The problem at the moment is I don't understand the mechanism by which the degradation arises.

I can't obviously measure the effect, yet I can hear it. It may be related to the waveform on the secondary - take a look at it with large caps in place - not really sinusoidal at all. This flat-topping gives some harmonic content we don't want, but adding series R before the caps doesn't improve the sound, just changes it.

A.
  Reply With Quote
Old 27th August 2002, 10:15 PM   #35
ALW is offline ALW  United Kingdom
diyAudio Member
 
Join Date: Jun 2001
Location: UK
Default Bam

Quote:
Using a transformer/rectifier/cap method is one of the crudest ways to get dc from ac that exists. It is like trying to levitate your body by being continually kicked up your backside
About the best description I've read yet

I've been meaning to try choke reg's - you've just spurred me onto trying it, along with another chat I had recently with a designer about the lost art of inductors!

Will report back when I try it.

A
  Reply With Quote
Old 27th August 2002, 10:30 PM   #36
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
Default Choke input

From the Radiotron Handbook:

Click the image to open in full size.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  Reply With Quote
Old 28th August 2002, 11:27 AM   #37
diyAudio Member
 
chris ma's Avatar
 
Join Date: Sep 2001
Location: Pickering, Canada
Red face Report Sir

Andy is right (ALW), Thanks.

I removed two 15,000uf from the rails, each rail now has one BHC Aerovox ALT22A 15,000uf 63V and bypassed by three 100nF polypropylene caps left on the rails. Kept everything else the same as before.

The sound of the amp changed ;
Treble now has more dynamic and forward, cymbal sound better than before, I do not know how to describe it but it sound clearer overall from mid to high frequency. The amp seems to be a bit more sensitive, but then it seems a little thin, more airy around instruments. Actually there is one track on a old CD clipped badly with high frequency during a particular short loud passage of the song. May be just the bad recording I do not know.

But the heat of the bridge rectifiers and the transformers got just as hot as before though. No luck there.

Andy, once you have found the optimum cap & tranny formulae please share with us...

Regards,
Chris
  Reply With Quote
Old 28th August 2002, 02:40 PM   #38
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
What about the bass?

I don't think that amount of capacitance has anything to do with the bridge temp. Once the caps are charged the current draw from the amp influences the bridge's temperature. Just put it on a heat sink and forget that it's hot. I placed my bridges on the same heatsink as output devices and they were around 55 deg.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 28th August 2002, 03:20 PM   #39
diyAudio Member
 
chris ma's Avatar
 
Join Date: Sep 2001
Location: Pickering, Canada
Default Bass? Not much changed that I can hear yet..

At first I thought the bass was reduced (first impression) right after the modification ; due to the more dynamic mid high caught my attention, then I turn my attention to the bass and ignore the mid high of a couple of recordings that I know best, is all there, just as same as before the mod.
I'll give it a couple of days listening then I will put one cap back per rail (2 X 15000uf per rail) to check the result. For now there are certain tracks it sounds just a little bit too bright in the vocal department for my liking. Mind you the cymbal and hi-hat sound great now. The track Ready for love by Bad Company sound really good with the drums now, used to sound a bit strangled, bass stays the same however, did not have time to listen to my reference CD yet the Sheffield test cd titled "My Disc". Will do that tonight.
  Reply With Quote
Old 30th August 2002, 05:57 PM   #40
diyAudio Member
 
Join Date: Dec 2000
Location: Önnarp, Söderslätt
Default Real-world picture:

planet 10.

I get very nostalgic when I see such a textbook picture.
This is what I've measured during the test of my LDO-regulator today:


Perhaps the phenomena in question has something to do with the relationship of the inductance of the secondary - the resistance from the secondary to the capacitors - the capacitance - and the waveform ??
Attached Images
File Type: jpg toroid secondary output waveform.jpg (28.1 KB, 802 views)
__________________
Regards
Hoffmeyer ;0)
  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
Need Help with + _ 90-100 volt regulated power supplies wrich22 Power Supplies 4 21st March 2008 10:46 PM
Regulated power supplies and capacitance Greg Erskine Chip Amps 33 3rd October 2004 09:56 PM
Regulated power supplies in a Gainclone Dr.H Chip Amps 30 11th September 2003 06:55 PM
FS: (2) 28 VDC 11 AMP regulated power supplies. FEThead Swap Meet 1 2nd May 2002 04:18 PM
Regulated power supplies Jason Hubbard Solid State 20 10th September 2001 08:33 PM


New To Site? Need Help?

All times are GMT. The time now is 02:07 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