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 26th June 2008, 09:21 AM   #41
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
start at the output and work back to the input transistors.

Assume that the output bias is XmA. (2mA is a good starting guess but I suggest you look at 1mA, 2mA and 4mA of output bias to see what happens to input Vbe).
The output Vre=[4.7*X]mV
The base of the output devices sits at output [Vbe + 4.7X]mV away from output voltage.
The voltage @ the bases of the output pair exactly equals the Vbe of the input pair.
Input Vbe=output Vbe+4.7X

Now look up the datasheet and find what current is required in the input stage to require that input Vbe to exist.
If it does not equal the input bias current then select another output bias current and try again.

But, go back and read PMA again. Set 12mA for the output bias and do the calcs for the devices & values PMA has selected.

This is simple arithmetic, no EE qualifications needed here.
__________________
regards Andrew T.
  Reply With Quote
Old 3rd July 2008, 01:20 AM   #42
darian is offline darian  France
diyAudio Member
 
Join Date: Mar 2006
Location: Paris
Hello again,

I wanted to let you know I found my answer. I just forgot to really take into account the Vbe serie internal resistor in my calculus because I thought it is so little it could be quasi neglected. I was wrong! I would have liked someone here to point it to me but whatever... I could "do-it-myself" after all and that's the real point...

Thanx
  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
HDAM / Diamond Buffers Q RnR Solid State 0 21st April 2009 09:59 PM
A question about diamond buffers darian Analog Line Level 3 24th June 2008 07:38 PM
Diamond buffers Nordic Parts 7 13th March 2007 02:13 PM
Mini Portable Headphone Amplifier, with Discrete Diamond Buffers cetoole Headphone Systems 3 30th May 2006 06:32 AM
Diamond buffers w. CFP outputs Christer Solid State 39 26th January 2004 11:08 PM


New To Site? Need Help?

All times are GMT. The time now is 12:28 AM.

Page generated in 0.07336 seconds (70.57% PHP - 29.43% MySQL) with 11 queries

Copyright ©1999-2012 diyAudio