Question about output Transistors - diyAudio
Go Back   Home > Forums > Design & Build > Parts

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

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 October 2007, 04:24 PM   #1
diyAudio Member
 
Join Date: Mar 2007
Send a message via MSN to Denis.BR
Default Question about output Transistors

Hey people!

I have a question just for curiosity: I foud this amp, a Gradiente Model 80 in a pawn shop for a very cheap price. Its a vintage, with 30 years old but it works perfectly, with all the original components in place.

But I was watching the wiring diagram and noticed that the output transistors are two NPN RCA3055.

I'm not a genious in electronics, but I thought that the output transistors should be one NPN and one PNP.

How does a circuit like this works?

Edit: you can find the diagram at http://www.4shared.com/file/17216381/b0ac6fc5/m80.html
  Reply With Quote
Old 15th October 2007, 04:38 PM   #2
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
Not necessary
If you look closely you see that the signal to the Base of the negative output 3055 comes from the collector of the driver transistor (the signal to the 3055 base has been inverted)
Attached Images
File Type: jpg 80.jpg (60.7 KB, 177 views)
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 15th October 2007, 04:47 PM   #3
diyAudio Member
 
Join Date: Mar 2007
Send a message via MSN to Denis.BR
I see..

So the T802 amplifies what the T107 pre amplified? What is the advantage?
  Reply With Quote
Old 15th October 2007, 04:53 PM   #4
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
No special advantages...
Just another way to do it
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 15th October 2007, 04:55 PM   #5
diyAudio Member
 
Join Date: Mar 2007
Send a message via MSN to Denis.BR
Nice! one more information for the data bank!

Thanks a lot!
  Reply With Quote
Old 15th October 2007, 04:57 PM   #6
diyAudio Member
 
Jan Dupont's Avatar
 
Join Date: Apr 2003
Location: Copenhagen, Denmark
Send a message via MSN to Jan Dupont
You're welcome
__________________
Free Schematic and Service Manual downloads www.audio-circuit.dk, Company: www.dupont-audio.com, Joint venture: www.DupontMantra.com
  Reply With Quote
Old 17th October 2007, 12:51 PM   #7
diyAudio Member
 
Join Date: Mar 2007
Send a message via MSN to Denis.BR
And what about these capacitors in the output? They are foi coupling, right?

What happens if I decrease or increase it's value?
  Reply With Quote
Old 26th October 2007, 10:35 PM   #8
diyAudio Member
 
Join Date: Dec 2003
Location: Orange County, CA
Default Quasi-Complementary

The quasi-complementary output using 2 NPN transistors was used because in the mid 60s high power silicon PNP transistors were not really invented yet. They did not come out until about 1970 and we then moved to fully complementary amplifier output stages.
__________________
Dan Fraser
  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
Question about audio output transistors and power out ElectronicsTech Solid State 24 3rd May 2009 03:08 AM
output transistors pezza89 Vendor's Bazaar 0 2nd November 2007 11:14 PM
Long output lead or long output transistors leads? which one to pick? chris ma Everything Else 3 6th June 2003 01:06 PM
Output Transistors weinstro Parts 1 9th May 2003 12:51 PM


New To Site? Need Help?

All times are GMT. The time now is 10:01 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