Fast Recovery rectifier diodes - 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 23rd October 2005, 03:37 PM   #1
diyAudio Member
 
Join Date: Sep 2005
Default Fast Recovery rectifier diodes

I had a transformer and power supply unit quoted for a project, and in the quote, the secondary of the toroid is rated at 20A rms, but peak pulses of ~110A could occur. Should I get rectifier diodes rated at 110A, or is ~50A sufficient?
  Reply With Quote
Old 23rd October 2005, 06:54 PM   #2
diyAudio Member
 
Join Date: Apr 2005
Location: Tallinn
It may sound odd, but this rating depends at least on: a) the type/manufacturer of the rectifier diode, b)pulse time.
You should search some diode datasheets, because probably noone can say whether 50A rms diodes from a random manufacturer can handle 110A peak.
And there's another thing that you should consider. Are your pulses going to be repetitive (i.e. because of the loud music ) or non-repetitive (i.e. because of capacitors' charging during power-on).
If second, you can use 30EPH06 diodes, that I've used in my PSU. They have have a continuous current rating of 30 A and a peak non-repetitive current of 300 A.
  Reply With Quote
Old 23rd October 2005, 07:15 PM   #3
hughmon is offline hughmon  United States
diyAudio Member
 
Join Date: Jun 2004
Location: Los Angeles
Here's some interesting diodes from Cree. They're silicon carbide schottky diodes and exhibit a positive tempco in their forward voltage, which means that you can parrallel them for higher current ratings, and with no reverse recovery time to speak of, and low leakge (at least for a schottky type diode), may be an interesting option:

http://www.cree.com/products/pdf/CSD20030.pdf
  Reply With Quote
Old 24th October 2005, 06:27 AM   #4
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
No need for exotic, expensive diodes; if this is line frequency, standard recovery silicon diodes will suffice.

I can't think of a single diode made for power rectification that isn't rated for an absurd number of peak amperes. The 1N4001 is rated for 1A rms but 30A peak. I think the 35A FWBs I have on hand are rated for like 625A peak...

Unless you have an absurdly high input capacitor with absurdly low ESR, you don't have to worry about peak current at all. Besides, your transformer will melt from the massive RMS current long before the diodes will.

Tim
__________________
Seven Transistor Labs
Projects and Resources
  Reply With Quote
Old 24th October 2005, 09:44 AM   #5
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally posted by Sch3mat1c
No need for exotic, expensive diodes; if this is line frequency, standard recovery silicon diodes will suffice.

I can't think of a single diode made for power rectification that isn't rated for an absurd number of peak amperes. The 1N4001 is rated for 1A rms but 30A peak. I think the 35A FWBs I have on hand are rated for like 625A peak...

Unless you have an absurdly high input capacitor with absurdly low ESR, you don't have to worry about peak current at all. Besides, your transformer will melt from the massive RMS current long before the diodes will.

Tim

Thanks Tim, we should all be gratefull for this reality check....

Jan Didden
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W S Maugham
Check out Linear Audio!
  Reply With Quote
Old 24th October 2005, 03:16 PM   #6
hughmon is offline hughmon  United States
diyAudio Member
 
Join Date: Jun 2004
Location: Los Angeles
Quote:
Thanks Tim, we should all be gratefull for this reality check....
Heaven forbid some people would be interested in a little general knowledge to add to their repertoire.

IMHO, the whole point of DIY is lost if all you're doing is making stuff that the Pacific rim pumps out at a fraction of the cost that you can.

I once pulled some what appeared to be underated diodes out of the analog section in a Magnavox CD player and replaced them with some standard devices, thinking that it wouldn't effect the sound. To my surpriser it totally screwed up the sound. Had to put the originals back in. In my experience, the power supply very much effects the sound of a system, and even the lowly diodes can have an influence in a high definition system.
  Reply With Quote
Old 24th October 2005, 03:27 PM   #7
diyAudio Member
 
analog_sa's Avatar
 
Join Date: Aug 2002
Location: Sofia
Quote:
To my surpriser it totally screwed up the sound

What, you actually listen?! And don't feel embarassed to reveal this to the experts?



More seriously, there are a couple of threads on the tweakers asylum about the Cree diodes. Exotic and expensive, maybe, but not to everyone's liking. I still haven't had a chance to plug in mine but if myth-busting is the theme of the day i might do it tonight.
  Reply With Quote
Old 24th October 2005, 03:53 PM   #8
hughmon is offline hughmon  United States
diyAudio Member
 
Join Date: Jun 2004
Location: Los Angeles
Quote:
More seriously, there are a couple of threads on the tweakers asylum about the Cree diodes. Exotic and expensive, maybe, but not to everyone's liking. I still haven't had a chance to plug in mine but if myth-busting is the theme of the day i might do it tonight.
I haven't tried them yet either. I've been waiting for the technology to mature a little, more specifically, I'm interested in the smaller one amp devices for pre-amp applications (if they ever make them available in a smaller package). As far as price goes, I would expect that to come down in time also, just as it has for what was once considered "exotic" blue LEDs, now commonplace.

I'd very much be interested in what conclusions you come to about the Crees when you try them.
  Reply With Quote
Old 24th October 2005, 04:50 PM   #9
sss is offline sss  Israel
diyAudio Member
 
sss's Avatar
 
Join Date: Jul 2003
Location: Israel , haifa
Send a message via ICQ to sss
Quote:
Originally posted by hughmon
I once pulled some what appeared to be underated diodes out of the analog section in a Magnavox CD player and replaced them with some standard devices, thinking that it wouldn't effect the sound. To my surpriser it totally screwed up the sound. Had to put the originals back in. In my experience, the power supply very much effects the sound of a system, and even the lowly diodes can have an influence in a high definition system.
what was the purpose of that diode ? was it a part of a bridge rictifier?
__________________
if you are not living on the edge you are taking too much space
  Reply With Quote
Old 24th October 2005, 05:18 PM   #10
hughmon is offline hughmon  United States
diyAudio Member
 
Join Date: Jun 2004
Location: Los Angeles
Quote:
what was the purpose of that diode ? was it a part of a bridge rictifier?
It was the four diodes in the analog bridge. Very wimpy looking .5A switching diodes. As long as I was in there making some mods, I decided to replace them with some standard 1A rectifiers. I really didn't expect it to effect the sound, but man was I wrong. Looks like the designers of that unit knew something when they selected those diodes.
  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
schottky vs. soft/fast recovery diodes metebalci Parts 26 24th October 2010 05:29 AM
Fast recovery diodes help / advice please ? AndrewGM Solid State 17 15th April 2009 09:39 PM
Fairchild Stealth soft recovery fast switching diodes KevinLee Swap Meet 3 10th January 2006 09:53 PM
Nice power supply with fast recovery diodes peranders Solid State 3 24th August 2004 03:04 PM
200V 50A Fast Recovery POWER Rectifiers kilowattski Pass Labs 7 17th February 2004 04:15 PM


New To Site? Need Help?

All times are GMT. The time now is 09:57 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