Producing Triangle Waves - Page 4 - 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 9th September 2009, 03:51 PM   #31
nitrate is offline nitrate  United Kingdom
diyAudio Member
 
nitrate's Avatar
 
Join Date: Jun 2005
Location: England, Lancashire
81Bas,

Hardly any ringing at all, See the waveforms earlier in the thread. They are very clean
__________________
The perfect amplifier is a piece of wire with gain....
  Reply With Quote
Old 10th September 2009, 03:24 PM   #32
81bas is offline 81bas  Germany
diyAudio Member
 
Join Date: Jan 2006
Location: Kiel
Quote:
Originally Posted by nitrate View Post
Hardly any ringing at all, See the waveforms earlier in the thread. They are very clean
Absence of the ringing with big deadtime under NO load says nothing for me. Please, try to give some load (say 2-3 amperes), so the body diodes will enable during the deadtime, and post the waveforms here.
  Reply With Quote
Old 10th September 2009, 06:16 PM   #33
nitrate is offline nitrate  United Kingdom
diyAudio Member
 
nitrate's Avatar
 
Join Date: Jun 2005
Location: England, Lancashire
Deadtime is only 50n/s... I thought that was quite small LOL

There was no load tho... I'll load it up to 200W and see if it changes things, if it does i'll post the waveforms. I've burnt it in at full power for over 10min's before now and i cant remember seeing anything dodgey in the square.. i'll certaintly check for you tho..

Leigh
__________________
The perfect amplifier is a piece of wire with gain....
  Reply With Quote
Old 10th September 2009, 06:38 PM   #34
Pafi is offline Pafi  Hungary
diyAudio Member
 
Join Date: May 2004
Location: Budapest
Now the switching is half hard, half quasi-resonant, the second half is hard, and seems to be very fast, so the fact that ringing doesn't appear gives hope to work well also at full load, but the slow body diode of IRF640 will make losses relatively high. With music and real speaker there won't be a problem, but a continuous full current test may show more. (And waveform will change significantly for sure.) BTW: What is the bandwidth of scope and probe? Yesterday I explored a strong 240 MHz ringing in one of my amps despite the switching was not really fast (30-40 ns rise and fall time).

What is n/s?
  Reply With Quote
Old 10th September 2009, 07:04 PM   #35
81bas is offline 81bas  Germany
diyAudio Member
 
Join Date: Jan 2006
Location: Kiel
Quote:
Originally Posted by Pafi View Post
What is n/s?
It is obvious: nano/seconds

  Reply With Quote
Old 10th September 2009, 10:48 PM   #36
nitrate is offline nitrate  United Kingdom
diyAudio Member
 
nitrate's Avatar
 
Join Date: Jun 2005
Location: England, Lancashire
LOL, n/s = ns ... just my dodgey wayZ of notation
__________________
The perfect amplifier is a piece of wire with gain....
  Reply With Quote
Old 14th September 2009, 10:57 AM   #37
nitrate is offline nitrate  United Kingdom
diyAudio Member
 
nitrate's Avatar
 
Join Date: Jun 2005
Location: England, Lancashire
Ok,

Over the weekend i've had time to remove all switching PSU's one by one. I started by again removing the LT25XX switchin reg with a 12v SLA battery. No effect. I then replaced the low side DC-DC converter with Ni-cad memory backup battery's. No effect. I then romoved the last DC-DC converter. Also no effect at all on the whistling noise. Its definatly sensitive to having a finger near the cmos nand gates. Also sensitive to touching the low side fet. Apart from those two hot spots you can literally lick the board when its operating and have no effect on the whistle. It must be the main carrier some how getting back into the modulator.

I'm gonna put all the power supplies back to normal over the next few nights and think of somthing else. Very strange indeed. I may have to submit and go with self osc topology, or just close the loop and pretend its not there

Oh yeh.. Loading. When loaded up with a 4R resistive load and 1K sine the amp delivers full power at about +-42V Pk before cliping, 218W RMS, 7.4A Pk ( by calculation ). The only effect on the square is a 3V increase in overshoot spike. Nothing worth posting.

Has anyone any other thoughts on what can be causing the intermodulation noises? I'm about all out of ideas

Leigh
__________________
The perfect amplifier is a piece of wire with gain....
  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
4780 producing only hum: help needed! zenocosini Chip Amps 6 17th November 2005 04:27 PM
wich school is the best for producing ? hectik Everything Else 2 27th June 2005 07:00 AM
c3g producing sparks garbage Tubes / Valves 2 11th April 2005 03:03 AM
Tool for producing an LCR network that = a speaker+box? CeramicMan Multi-Way 2 27th May 2004 02:39 AM


New To Site? Need Help?

All times are GMT. The time now is 07:15 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