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

Solid State Talk all about solid state amplification.

Another simple BJT quasi-complimentary Amplifier
Another simple BJT quasi-complimentary Amplifier
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 15th April 2019, 01:49 PM   #11
FYC is offline FYC  Hong Kong
diyAudio Member
 
Join Date: Jan 2001
Location: Hong Kong
Quote:
Originally Posted by Osvaldo de Banfield View Post
As I can see, still there is no NFB loop to maintain the DC null at the output. A simple differential amplifier is much more effective. Try it.
In terms of DC null, LTP should be better. Nevertheless in the project I want to get some experience with current feedback.
  Reply With Quote
Old 15th April 2019, 01:53 PM   #12
FYC is offline FYC  Hong Kong
diyAudio Member
 
Join Date: Jan 2001
Location: Hong Kong
Quote:
Originally Posted by mchambin View Post
It helps bias stability.
An increase of Ibias, increases the voltage drop across the 2 x 0.33 ohm. This voltage increase is "seen" by the base spreader ( here a Vbe multiplier ) that will counter act the Ibias increase.
The bias stability is very good indeed. I thermally coupled the Vbe multiplier transistor with the BD139 driver transistor on the +ve side of the output stage. The drift is within 1-2% only.
  Reply With Quote
Old 15th April 2019, 01:54 PM   #13
Osvaldo de Banfield is online now Osvaldo de Banfield  Argentina
diyAudio Member
 
Osvaldo de Banfield's Avatar
 
Join Date: Dec 2011
Location: Barrio Garay,Almirante Brown, Buenos Aires, Argentina
OK, then be happy experimenting. But remember the stability problem.
__________________
Osvaldo F. Zappacosta. Electronic Engineer UTN FRA from 2001.
Argentine Ham Radio LW1DSE since 1987.
  Reply With Quote
Old 15th April 2019, 02:12 PM   #14
mchambin is online now mchambin  France
diyAudio Member
 
Join Date: Mar 2011
Quote:
Originally Posted by FYC View Post
The bias stability is very good indeed. I thermally coupled the Vbe multiplier transistor with the BD139 driver transistor on the +ve side of the output stage. The drift is within 1-2% only.
Quasi complementary has inherent good thermal stability thanks to 3Vbe base spread.
( Versus 2 with CFP, 4 with 2EF, 6 with 3EF ).
With the 2 x 0.33 ohm that give immediat biais correction, and the thermal coupling, this design is very safe from thermal runaway.
__________________
Transistor junction temperature is not transistor case temperature.
  Reply With Quote

Reply


Another simple BJT quasi-complimentary AmplifierHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Very simple quasi complimentary MOSFET amplifier Ranchu32 Solid State 2465 10th April 2019 09:45 AM
FS : Very simple quasi complimentary MOSFET amplifier PCBs with onboard PSU pinnocchio Swap Meet 3 19th September 2017 03:41 AM
Quasi complimentary MOSFET amplifier bordodynov Solid State 4 29th November 2016 11:21 AM
simple quasi complimentary MOSFET amplifier BUILDERS GUIDE meanman1964 Solid State 37 22nd November 2016 01:43 PM
Simple 200 watt complimentary FET amplifier (possibly tube driver?) deltavektor Solid State 6 15th May 2011 07:15 AM


New To Site? Need Help?

All times are GMT. The time now is 04:07 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki