Bruno Putzeys' reference UcD amplifier - 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 6th April 2006, 12:30 PM   #11
Account Disabled
 
Join Date: Feb 2004
Send a message via AIM to classd4sure Send a message via MSN to classd4sure
But you can attach PDF here... if it's a problem for size or something feel free to email it to me as well.
  Reply With Quote
Old 6th April 2006, 08:08 PM   #12
alfsch is offline alfsch  Germany
diyAudio Member
 
Join Date: Jan 2002
Location: augsburg
hi lenz,
kannst du mir den artikel auch senden?
alfsch at freenet.de
  Reply With Quote
Old 7th April 2006, 09:53 AM   #13
diyAudio Member
 
Join Date: Jul 2004
Location: Banagalore
LED's are used as a voltage reference. Combining with a transistor it forms a Constant current souce. This is a common scheme in any amplifier at the input stage where the compartor transistors need to be fed with a constant current source.
  Reply With Quote
Old 7th April 2006, 10:33 AM   #14
diyAudio Member
 
Join Date: Nov 2002
Location: germany
Ooooh sh...

Is it the possibility.

I can`t separate the 5 pages from the 88 pages pdf document .

How to do?
  Reply With Quote
Old 7th April 2006, 01:38 PM   #15
alfsch is offline alfsch  Germany
diyAudio Member
 
Join Date: Jan 2002
Location: augsburg
hmmm...
a: send pdf with all pages
b: try: http://www.cutepdf.com/Products/CutePDF/writer.asp
--> http://www.cutepdf.com/download/CuteWriter.exe
  Reply With Quote
Old 7th April 2006, 05:17 PM   #16
Account Disabled
 
Join Date: Feb 2004
Send a message via AIM to classd4sure Send a message via MSN to classd4sure
Quote:
Originally posted by anant_narayan
LED's are used as a voltage reference. Combining with a transistor it forms a Constant current souce. This is a common scheme in any amplifier at the input stage where the compartor transistors need to be fed with a constant current source.

I think that's just one example of its use as a voltage reference.

What we should look at it is why it's possibly a better voltage reference than say, a zener for instance. Is it better than better than a proper reference as well? Or possibly just a quick and easy/cheap way of attaining a reasonable reference, without say resorting to band gaps etc.
  Reply With Quote
Old 18th April 2006, 06:37 PM   #17
T0kiman is offline T0kiman  Belgium
diyAudio Member
 
Join Date: Sep 2005
If i'm not mistaking they wrote something about Bruno finding the zeners much to noise for the purpose they were used in. With this in mind i thought he must not be the only one thinking of this. I stumbled on an article of maxim where they use a zener as a white noise generator. The noise is created by the reverse breakdown process wich, for zeners with reverse voltages greater than 5.6V, is called avalanche breakdown. This is a random process of collisions of moving free carriers in the depletion region and fixed atoms. I can imagin that this process creates noise of some sort. I could be wrong to.

Also maybe a good question to ask is how much the zener voltage is dependent of temperature and power supply changes comparing to a normal led.

regards,

Thomas
  Reply With Quote
Old 18th April 2006, 07:04 PM   #18
diyAudio Member
 
Join Date: Dec 2005
Location: Berlin
Lenz mailed me (thank you!) an article about LEDs as a constant current source. Since the article is in german and even though i am german i hardly understand it i probably shouldn't be the one to translate it here. I could post some (easy) schematics (but only next week) if anyone is interested.
  Reply With Quote
Old 18th April 2006, 07:18 PM   #19
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Some time ago, somebody did quite extensive LED and Zener noise and impedance measurements and published the results in some forgotten thread. The author was quite shy at making conclusions, but his measurements clearly showed the zeners below 8v2 or 10V (I don't remember exactly) to be the noisy ones, and the zeners above 8v2 or 10V to perform much better than the equivalent string of leds both in terms of noise and impedance.

The results also suggested that some colours and sizes of LEDs are noisier than others.
  Reply With Quote
Old 18th April 2006, 08:04 PM   #20
alfsch is offline alfsch  Germany
diyAudio Member
 
Join Date: Jan 2002
Location: augsburg
eva, you think of this..?
Some noise measurements for LEDs and zener 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
Bruno Putzeys in IEEE Spectrum MartinRF Class D 11 9th March 2008 09:58 PM
Bryston's interpretation of a Bruno Putzeys article mac Class D 5 24th October 2006 03:29 PM
What amplifier for reference? lumanauw Solid State 44 17th April 2004 09:18 PM


New To Site? Need Help?

All times are GMT. The time now is 03:34 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