Germanium PNP transistor based amplifier (OC36) - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

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 14th December 2014, 02:53 PM   #1
diyAudio Member
 
Join Date: Apr 2014
Default Germanium PNP transistor based amplifier (OC36)

I've just recently been interested in building some amplifiers, which I've done with modern transistors just fine. But I have this box of much older transistors, all in TO-3 packages, and was curious if I could use of these in a project.

Among them is a handful of OC36 germanium transistors, I've seen some 'vintage' schematics use the OC71 for example. The most interesting is that the OC36 is very similar to the 2N278 in specifications, and the 2N278 is a power transistor made for class A and AB stage amplifiers.

Anyone know if the OC36 could be used in an audio amplifier? Anyone know of schematics based on germanium PNP transistors?

Something along the lines of Click the image to open in full size.

Thanks
  Reply With Quote
Old 14th December 2014, 07:22 PM   #2
sbrads is offline sbrads  United Kingdom
diyAudio Member
 
Join Date: Jun 2005
Location: Kent, UK
When I was 13 in the 60's I made my 1st amp, a 4 watt class A valve kit and it sounded nice considering the cheap speakers and record decks in common use then. I then started learning about semiconductors which was just about all PNP germanium stuff then and I made an amp using a pair of (similar to OC36) OC35's. It did not sound good or go anywhere near as loud as the 4 watt valve amp despite being higher wattage, 10 watt I believe. That experience got me very interested in Hi-Fi and led to a long path of upgrades before I was happy with the sound quality. So, build one for interest's sake but don't expect much, and they blow up really easily! That AD140 class A circuit looks a bit weird and wastes a load of power in R22, I wouldn't use that.

Last edited by sbrads; 14th December 2014 at 07:31 PM.
  Reply With Quote
Old 14th December 2014, 07:52 PM   #3
diyAudio Member
 
Join Date: Apr 2014
Yeah, I don't expect any high quality audio from it, it's just for the learning part of it. Another schematic I've found using the 2N278 is this one: http://www.radiomuseum.org/images/tu...278_umgeb1.png

I can't find a larger picture of that unfortunately.
  Reply With Quote
Old 14th December 2014, 08:13 PM   #4
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
If you search in my previous messages, you'll find large numbers of vintage/Ge amplifiers examples I have posted.
Some of them did sound very good actually.

That said, I agree with sbrads on the inefficiency issues of your circuit.
Even if you constrain yourself to PNP's throughout, there are better solutions.
__________________
. .Circlophone your life !!!! . .
♫♪ My little cheap Circlophone© ♫♪
  Reply With Quote
Old 16th December 2014, 12:43 PM   #5
diyAudio Member
 
tubewade's Avatar
 
Join Date: Jun 2007
I used to build lots of PNP Ge amplifiers as experiments because they were cheap and easy to find. They are not tolerant of any overvoltage situation and I got the best result from them using autotransformer coupled outputs. Some of them could make decent power from low B+ voltage and sounded pretty good as booster amplifiers for portable radios, etc. Fun, fun tinkering on the cheap.

I still have a few amplifiers around with Ge output devices. One of them is a Sylvania Exponent 4/40 portable stereo phono system. It sounds very good for a portable system from 1966.

Kind regards.
  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
Germanium transistor madness Captain archer Solid State 15 16th January 2013 03:42 AM
question about germanium based amps ke4mcl Solid State 13 26th November 2011 02:49 AM
AC128 PNP Germanium Transistor Spice Mode (RARE!) pweaudiotech Solid State 57 11th January 2011 12:55 PM
Need Old Germanium transistor datasheets Bakmeel Parts 9 3rd June 2009 08:43 PM
what are the best germanium transistor npn and pnp ?? prorms Instruments and Amps 9 24th August 2008 01:42 AM


New To Site? Need Help?

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