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

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Old schematic
Old schematic
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
Thread Tools Search this Thread
Old 23rd April 2012, 07:46 PM   #1
Hojvaelde is offline Hojvaelde  Denmark
diyAudio Member
Join Date: Jan 2005
Location: Denmark
Default Old schematic

For information

I've got a somewhat electronic scrap / schematics from an estate (a +90 year man).

I found the schematic here, which I've attached.
There comes several schematics as I have drawn them clean.

Here is one schematic with, for me unknown low-voltage tube, 50B5.
I would probably raise the voltage and use EL90 tubes.
You must be disregarded pin numbers on the tubes.


Attached Files
File Type: pdf 50B5 pp.pdf (10.4 KB, 172 views)
  Reply With Quote
Old 23rd April 2012, 09:45 PM   #2
Miles Prower is offline Miles Prower  United States
diyAudio Member
Miles Prower's Avatar
Join Date: May 2005
Location: USA
Originally Posted by Hojvaelde View Post
Here is one schematic with, for me unknown low-voltage tube, 50B5.
The 50B5 is identical to the 50C5, however, the pinouts are different. That was the big problem with the 50B5: it has the same pinout as the 6AQ5, but that caused problems when using the 50B5 in a series string, as the voltage could be quite high before it warmed up. So they changed the pinout, and made the 50C5.
There are no foxes in atheistholes
  Reply With Quote
Old 23rd April 2012, 10:50 PM   #3
payloadde is offline payloadde  Europe
diyAudio Member
payloadde's Avatar
Join Date: Mar 2008
Judge: This court appreciates that you invented physics, Mr.Newton, but unfortunately you can't have a patent on it.
  Reply With Quote
Old 23rd April 2012, 10:56 PM   #4
Eli Duttman is offline Eli Duttman  United States
diyAudio Member
Join Date: Apr 2004
Location: Monroe Township, NJ

The 50B5 data sheet is here.

That circuit is typical of cheap, LOFI, AC/DC designs. It used a transformerless 1/2 wave rectified B+ PSU and a 150 mA. series heater string. It's inexpensive and deadly dangerous. The only protection the owner got was from the floating speaker setup. Notice zero NFB in combination with full pentode mode. That means lots of distortion and wretched voice coil control.

It's not that long ago that folks living in certain localities were forced to use equipment of that ilk. Their house current was "110" VDC.

A good amp can be built around that sort of power tube, but not with that crappy PSU. Bridge rectify "120" VAC. 0B2 regulate g2 B+. You can bank on that design being used with a piezoelectric phono cart. as the signal source. HF info. was already rolled off. The parts values shown will cause HF info. loss, if a full range signal is applied.
Eli D.
  Reply With Quote
Old 24th April 2012, 07:20 AM   #5
Hojvaelde is offline Hojvaelde  Denmark
diyAudio Member
Join Date: Jan 2005
Location: Denmark

Peaceful Eli. I had no intentions of building the amplifier. I showed it just as an example of a design from the late forties, early fifties.

I have found the following designs in the estate.
6SJ7-6N6-6V6 in pp
Something 6SQ7 - 6V6 in pp
6SJ7-6SN7-6L6 in pp
12SQ7 - 12L6 in SE

There are more but I have no overview at the moment.

  Reply With Quote


Old schematicHide 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
Linn "LINTO" MC Preamp Schematic without SMPS - Schematic for SMPS wanted tiefbassuebertr Analogue Source 42 7th June 2018 08:04 AM
Schematic needed panasonic RX-1230 schematic Buzzsaaw Analog Line Level 0 23rd April 2011 07:52 PM
Please look this schematic ketsada Solid State 4 17th November 2005 06:26 AM
Help with this schematic? imix500 Parts 4 11th August 2004 10:08 AM
I need a schematic. mbates14 Tubes / Valves 2 24th September 2002 07:25 PM

New To Site? Need Help?

All times are GMT. The time now is 02:27 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio