Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles Store Gallery Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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 16th April 2010, 08:16 PM   #1
larryB is offline larryB  Canada
diyAudio Member
 
Join Date: Apr 2010
Default Rate and comment my poweramp design

This is a power amp I have in mind , plz do not laugh yes I work things out brute force with my scope and breadboard , I am not a sim guy .

Here is the design I have in mind , input will be a sine wave about 2 V p-p anywhere from 300 hz to 20 khz . I am using op amps as phase splitters to drive the mosfets . This is what I believe to be a class A transformer coupled push-pull modified by me .

Mosfet will probably be a class-d lateral mosfet with 900 pf input capacitance and 12 , still choosing . Op amp is the lm8261 , wich is just perfect for my application from the looks of it .

So I am gonna be running 2 x mosfets per amp , so 1800 pf input , yes Its strange i know .

Transformer secondary is floating , load might be anything from capacitive to inductive , put an x value , I am not aiming for maximum power in 8 ohms or w/e , this can go from a couple mA to large amps , most likely a slightly reactive load load ... I wont go beyond 6 amps on the secondary side .

Transformer will be either 1:1 or 1:2 step up audio range type .

Plz tell me if this is good , is the biasing resistors good like this ? Do I understand things correctly ?
Attached Images
File Type: jpg POWERAMP.JPG (75.3 KB, 173 views)
  Reply With Quote
Old 16th April 2010, 10:48 PM   #2
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
It will run in class b and have crossover distortion as it stands.
__________________
http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.
  Reply With Quote
Old 16th April 2010, 11:51 PM   #3
larryB is offline larryB  Canada
diyAudio Member
 
Join Date: Apr 2010
How can I make this same design run in pure class A , isnt the resistor biasing making this class A
  Reply With Quote
Old 16th April 2010, 11:52 PM   #4
larryB is offline larryB  Canada
diyAudio Member
 
Join Date: Apr 2010
How can I make this same design run class A , I tought the resistors were doing that ?
  Reply With Quote
Old 18th April 2010, 07:45 AM   #5
ontoaba is offline ontoaba  Indonesia
diyAudio Member
 
ontoaba's Avatar
 
Join Date: Nov 2009
Location: Kudus, & Malang
No, the opamp forcing the resistor for do nothing.
  Reply With Quote
Old 18th April 2010, 10:42 AM   #6
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
larryB;

Look at your design again.
With 0 Volts at the input your Opamps will try to set their outputs at 0 Volt.
Result: The Opamps will just draw Current through the resistors connected to +15 Volts until output is 0 Volt (as on the input).
You need to add a biasing circuit between the Opamp outputs and the output Fets......
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote

Reply


Hide this!Advertise here!

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
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
Please rate this psu design Groundloops Power Supplies 8 15th October 2007 09:46 PM
Comment on my DIY Sub Design htgeek Subwoofers 22 8th April 2005 05:26 AM
Please comment this design promise Solid State 0 20th January 2005 05:25 AM
comment on this design, please. JAZZ2250 Tubes / Valves 6 24th November 2002 10:45 PM
howzabout this for a poweramp design? mlloyd1 Solid State 4 14th May 2002 09:38 AM


New To Site? Need Help?

All times are GMT. The time now is 08:04 PM.

Page generated in 0.09177 seconds (74.51% PHP - 25.49% MySQL) with 11 queries

Copyright ©1999-2012 diyAudio