cheap usb oscilloscope for measuring amplifiers - Page 3 - 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 4th September 2007, 01:08 PM   #21
diyAudio Member
 
umut1001's Avatar
 
Join Date: Mar 2007
Location: Istanbul
Default nothing

ok..chocolate..i know all about this aspirin..please tell about mosfets..if u know..if u dont know you cannot tell of course
  Reply With Quote
Old 4th September 2007, 01:48 PM   #22
diyAudio Member
 
Join Date: Dec 2003
Location: Munich
For the MosFet selection you must know your desired power. This will lead to a certain requirement for voltage , current ratings and Rdson of the MosFet.
You should not use MosFets which are much to strong, because they are more difficult to drive. Also above 100V it is difficult to find types with low Qrr of the body diodes.

1. Define the proper MosFet rating.
2. Search for a MosFet with the best trade off from Qrr (most critical), Qdg (second critical) and Qgs (third).
3. Design proper low side and high side driver + level shifter, or decide to use a halfbridge driver IC.
4. Have a look to the switching behavior of the power stage before you build the entire amp. Layout is one of the keys for good results.
5. Complete the amp by your favourite modulation principle and of course also output filter.

Point 4 might influence your consumption of acetylsalicylic acid products.
  Reply With Quote
Old 4th September 2007, 02:16 PM   #23
diyAudio Member
 
umut1001's Avatar
 
Join Date: Mar 2007
Location: Istanbul
Default choco

ok..i decided to make a sub amplifier..i did a 20hz-20khz in the past..but didnt work well..now i have tl072 ne5532 and lm4562..i will use one of them.2 ir2110..i decided to make full bridge sub amplifier..i want to have good bass and low thd..i have 16amperes 33,6volts toroidal transformer.and i want 200watts rms .what do you prefer?are st stripfets good choice?
cherry is a naturel aspirin..do not use much asetilsalisilik asit (in my language)..harmful for stomach and intestines
  Reply With Quote
Old 4th September 2007, 03:02 PM   #24
diyAudio Member
 
Join Date: Dec 2003
Location: Munich
So you are going for a single supply around 50V unloaded, correct? With a full bridge this could work to get something around 200Wrms into 4 Ohms...
For the MosFets you should search multiple brands and compare their types around 80V (at least 60V) / 15A.

Post a comparison list with brand&type, voltage rating, current rating, Rdson, Qrr, Qdg & Qgs. Then we can see...

If you really only want it for a sub, then there is not need at all for switching frquencies above 100kHz.
I think your OP amps are OK for an error correction gain stage, but they will not satisfy you in comparator operation.
  Reply With Quote
Old 4th September 2007, 03:18 PM   #25
diyAudio Member
 
umut1001's Avatar
 
Join Date: Mar 2007
Location: Istanbul
Default choco

as comparator i have lm360 and lt1016..i made a triangle wave generator with cd4069 gates as intersil hip4081 evo board..
yes 33,6*1,41 it will be 47volts...mosfets have 60volts vdss

there are some choices about mosfets

STF40NF06
STP60NF06L
STD20NF06LT4 it is d pack
and also irf540 st
what do you think?is input capacitance not important?
what can i do ?may i use feedback or not?it will be a full bridge?does it really need feedback
  Reply With Quote
Old 4th September 2007, 03:34 PM   #26
fumac is offline fumac  China
diyAudio Member
 
Join Date: Oct 2006
Send a message via MSN to fumac
i think , a full bridge for beginning is not a good choise


rg

fumac
  Reply With Quote
Old 4th September 2007, 03:51 PM   #27
diyAudio Member
 
umut1001's Avatar
 
Join Date: Mar 2007
Location: Istanbul
Default full bridge

i am making a pcb nowadays..i am using two ir2110..it is hard to do but i believe that it is better to make a sub amplifier full bridge..
  Reply With Quote
Old 5th September 2007, 02:33 PM   #28
diyAudio Member
 
Join Date: Dec 2003
Location: Munich
Default Re: choco

Quote:
Originally posted by umut1001

what do you think?is input capacitance not important?
what can i do ?may i use feedback or not?it will be a full bridge?does it really need feedback

Input capacitance is corresponding to Qgs. It is important.
Reverse transfer capacitance is corresponding to Qgd. It is very important.
I prefer to look at the charges instead of the capacitances, because the capacitances are nonlinear capacitances. Furtheron you have to take ino account that Crss has to be charged to much higher voltages than Ciss, means even a small looking Crss might need more charge than the bigger Ciss.....

It does not really NEED feedback, but in most class D designs it is quite fortunate.

Full bridge vs halfbridge:
The full bridge has the disadvantage of double component count.. Also you have two times the dead time related distorsions.
But the advantage is that you have less issues with the poor freewheeling diodes of high voltage MosFets, because you do not need high voltage types.
Another advantage is that a full bridge does not cause so much supply voltage pumping.
  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
Measuring Hi-Fi Amplifiers korneluk Tubes / Valves 5 15th July 2009 04:16 AM
oscilloscope at victoria st. vinnie's. twelve bux, cheap! maxro Swap Meet 6 15th March 2006 06:54 AM
pro amplifiers vs. home audio amplifiers bonsai171 Solid State 26 25th February 2004 09:24 PM
Paradigm amplifiers? Anthem amplifiers? Corn-Picker Solid State 2 24th January 2004 04:10 AM
Many smaller amplifiers vs. bigger amplifiers. djdan Solid State 9 17th September 2002 05:40 PM


New To Site? Need Help?

All times are GMT. The time now is 02:03 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