Power Supply Resevoir Size - Page 51 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 10th August 2012, 11:14 AM   #501
Banned
 
Join Date: Aug 2012
Quote:
Originally Posted by dadod View Post
I am sorry to intrude in this very interesting thread, but I was provoked by this guy telling nonsense about C multirplier .
dado
So explain why its not nonsence.
  Reply With Quote
Old 10th August 2012, 11:21 AM   #502
Account disabled at member's request
 
Join Date: May 2006
Quote:
Originally Posted by jacco vermeulen View Post
The latest Dartzeel 458 monaurals each have a 2KVA toroidal with a huge oversized core, 4.5 times the nominal power rating.
Mr Hervé Delétraz is from your turf, the things cost 150K a pair, you must find that Hilarious too.
150k

These must have more carats of gold in the front plate than the Goldmunds

What do these designers (company) ( used in the absence of a more appropriate smiley ) ??
  Reply With Quote
Old 10th August 2012, 11:54 AM   #503
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
$
__________________
The buck stops Here
  Reply With Quote
Old 10th August 2012, 09:24 PM   #504
Banned
 
Join Date: Aug 2012
Quote:
Originally Posted by liching1952 View Post
amps need a big cap not to minimize ripple but for another reason. This is neglected and even canceled by the circuit you called C multiplier. In fact its a Cap divider. Huh?
Me tupid you smart, where is the answer?
And why you people so seeking low ripple. Good Ampi dun need ripple free supply and ripple will not reach speaker.
Looks like you people dun know how much ripple is tolerable.
  Reply With Quote
Old 10th August 2012, 09:59 PM   #505
diyAudio Member
 
Join Date: Mar 2008
liching1952, you could try reading the thread. for comprehension this time.
  Reply With Quote
Old 10th August 2012, 10:14 PM   #506
Banned
 
Join Date: Aug 2012
Quote:
Originally Posted by Terry Given View Post
liching1952, you could try reading the thread. for comprehension this time.
Me inglish is too bad to read all that. As me understand its very simple and only me newcomer dun understand. So tell me in simple Inglish what much ripple do you want and why cause at me electronic level, ripple is not an issue for good profesional design ampi.
  Reply With Quote
Old 10th August 2012, 11:18 PM   #507
diyAudio Member
 
Join Date: Sep 2011
This thread isn't much about ripple; ripple is just *one* small factor in the main subject called "Transient Response" of the whole chain.
__________________
Negative Feedback: The Need for Speed
  Reply With Quote
Old 10th August 2012, 11:38 PM   #508
diyAudio Member
 
Join Date: Mar 2008
liching1952, that is just trolling. you are at least trilingual, and from what you've posted so far your english is more than sufficient for the task at hand - Ni Shuo Huai Hua. besides, with your MSc you should be able to follow the schematics and plots. that you have not and will not do so suggests you are either lazy or stupid. I'm assuming lazy.

As MagicBox points out, the thread is about transient response.

Why low ripple? stupid question. have you ever heard of PSRR? what about Early Voltage? cascoding?
  Reply With Quote
Old 11th August 2012, 03:22 AM   #509
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Every village has a fool.
__________________
Kindest regards
Nico
  Reply With Quote
Old 11th August 2012, 05:35 AM   #510
diyAudio Member
 
Join Date: Mar 2008
I'm just playing with the xfmr-rectifier-cap setup. Toms model, one transformer driving a MBR20100 full bridge into a 5R load with N * 1.2mF 26mOhm caps in parallel.

and I didnt see quite what I expected to see - above about 10mF the conduction angle is constant. thats odd. so I started looking a bit harder. it looks like its the combined effect of ESR (xfmr + diodes + cap bank) & leakage inductance that prevents the conduction angle from narrowing further - IOW it limits the peak current.

The transformer winidng resistances are interesting. Its a forward-mode transformer so the RMS primary and secondary currents are closely related - Ip = Is/N + Imag (this aint necessarily so in a coupled inductor).

generally one designs Imag = small (this is why the huge ratio of Lmag to Lleak - Lmag must be >> Lbase and Lleak << Lbase) so Ip = Is/N. One normally assigns equal volume to equal power windings - so the primary winding area Aw_p should be roughly equal to the secondary winding area Aw_s. Filling this up with Cu then results in Rp = Rs*Np^2. and the resistive losses in each winding are therefore equal (casually ignoring skin & prox effect)

yet in this case Rp/N^2 = 157mOhm but Rs = 290mOhm - the secondary resistance is 1.85x what I would expect it to be. so ignoring magnetising current the secondary accounts for 1.85/2.85 = 65% of the total copper losses.

I might expect to see that in, say, a microwave oven transformer where the poor thing runs hard into saturation (some MOTs draw less current under load because the voltage droop across the primary leakage pulls the core out of saturation. it makes it hard to spot a dead transformer if you dont know this). But nobody in their right mind would do that to a transformer running continuously. and beside with Lmag = 52H the mag current is < 10mA.

It might be to do with the thermal behaviour - if the secondary is on the outside of a toroid it will cool better. I dont know, I havent designed any LF toroidal transformers, but it still seems like a poor idea - especially as it hurts regulation.

the high Lmag seems odd too - 6mA magnetising current is stupidly low* at 120VA thats 0.6% of load.

One would normally pick a number, say 10% full load and design Imag = that much. this reduces the number of turns, and the leakage goes down (and regulation improves). Maybe the manufacturer was trying to get stupidly low Bmax for some reason? who knows, but its certainly odd.

*I used to have a 100kW three-phase 400V:208V transformer with Imag = 200mA (about 0.1%), but that was designed to be switched on and off hundreds of times per day, so was not allowed to "boing" so it had a peak flux density of about 400mT IIRC.

that might be whats happening here - if this transformer were designed for minimum inrush (which is utterly pointless if it then drives a thumping great rectifier-capacitor load) it explains the low Imag and the high leakage.

this transformer might turn out to be a TERRIBLE choice for modelling power supply interactions
  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
Valve power supply - How to size transformer? SanderW Power Supplies 25 4th January 2013 04:12 PM
How do you calculate choke size in a power supply? Original Burnedfingers Tubes / Valves 25 5th January 2012 12:23 AM
power supply bypass cap size BigE Power Supplies 11 5th July 2011 02:59 PM
Power Supply Case Size diymixer Power Supplies 1 10th October 2010 05:47 AM
What size power supply should I get for repair work? spooney Car Audio 3 6th December 2007 11:50 PM


New To Site? Need Help?

All times are GMT. The time now is 08:25 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