Interesting schematic - 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 13th March 2008, 03:51 AM   #1
diyAudio Member
 
Join Date: Oct 2006
Post Interesting schematic

Check out this little circuit! Any comments would be helpful as i intend to try this one out soon. It should be about 60w into 8ohms, and runs at 50khz. Notice the lack of output inductors?!? Should one be included even though the designer did not? There is a 'pulse shaping network' that looks like a zobel or snubber there, but...
Attached Images
File Type: jpg interesting schematic.jpg (49.3 KB, 2448 views)
  Reply With Quote
Old 13th March 2008, 04:22 AM   #2
diyAudio Member
 
Join Date: Nov 2007
1) I would choose a faster slewing opamp than the TL074.
2) Yes, an output filter will be necessary, if you plan to run your speaker wire more than a few inches (to prevent EMI)
3) Since +/-51 volts is way too high for a common linear regulator dual (LM317, LM337) without some pre-regulation, at the very least buffer the zeners with an emitter follower.
4) Much has been written about half-bridge topologies pumping the power supply. Don't know how serious this issue could be, but something you must be aware of.
  Reply With Quote
Old 13th March 2008, 01:11 PM   #3
fredos is offline fredos  Canada
diyAudio Member
 
Join Date: Mar 2005
Location: Quebec
I know this circuit...Old radio plan magazine..This amplifier was design for sub and run from floating 51V supply, not +/-51V...
  Reply With Quote
Old 14th March 2008, 12:02 AM   #4
diyAudio Member
 
Join Date: Oct 2006
I intend to use this for a small sub, and will mount the amp very close to the speaker, possibly allowing operation without an inductor. I may include an inductor, anyway, in the form of a 6db lowpass crossover at about 150hz. The power supply is labelled funny; it is really 51v total, +/-25.5v. Can an amp like this be bridged across the load (high enough impedance, of course) or would it be unstable in that configuration? I planned on just feeding an inverted signal to one channel. The circuit, BTW is from popular electronics magazine years ago, but I found it in a compilation of circuits in book form.
  Reply With Quote
Old 14th March 2008, 05:36 AM   #5
diyAudio Member
 
Join Date: Oct 2006
I have been working on a PCB and will post it soon if there is any interest.
  Reply With Quote
Old 17th March 2008, 08:21 PM   #6
latala is offline latala  United Kingdom
diyAudio Member
 
Join Date: Feb 2006
Location: staffordshire
I must admit that I have been looking for something like this for ages I am very interested in all your efforts re this amp
regards Trev
  Reply With Quote
Old 18th March 2008, 03:02 AM   #7
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
For one half bridge, how can we adjust dead time? Put something around Q1-Q3?
  Reply With Quote
Old 18th March 2008, 02:18 PM   #8
fredos is offline fredos  Canada
diyAudio Member
 
Join Date: Mar 2005
Location: Quebec
Change front op amp for LM319 fast comparator, add PNP-NPN buffer on each FET and add low pass filter and it will work decently...I start from this idea to design my D-Amp 1200....Do research on forum, you will find schematics.

Fredos
  Reply With Quote
Old 18th March 2008, 03:56 PM   #9
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
Hi, Fredos,

I'm looking for adjustable deadtime, but with comparator front end. UCD is adjustable, but it is discrete. I wanted to use fast comparator.

From my experiment, this one has too little dead-time, making cross-conduction when the mosfets are hot. There are phases where both mosfets conduct. I can only change a the supply for the totem pole (+/-10V) to adjust a little, but that's it.
Attached Images
File Type: gif 11_mk1-1b-schalt.gif (13.4 KB, 1687 views)
  Reply With Quote
Old 18th March 2008, 04:01 PM   #10
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
This one has too large dead time. Is there any adjustable dead time driver, where the comparator is only 1? Phase_Accurate's schematic is adjustable, but it use 2 comparator.
Attached Images
File Type: jpg a6rg2.jpg (37.9 KB, 1631 views)
  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
interesting amplifier schematic lt cdr data Solid State 2 14th May 2009 05:35 PM
Quite interesting onis_uk Multi-Way 11 9th February 2008 07:44 PM
interesting amp & interesting problem m6tt Tubes / Valves 9 14th August 2007 07:28 PM
These are interesting. G Full Range 4 3rd April 2007 10:43 AM
Interesting... mikeks The Lounge 4 24th May 2006 06:50 PM


New To Site? Need Help?

All times are GMT. The time now is 03:25 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