Go Back   Home > Forums > Amplifiers > Tubes / Valves

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

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 December 2012, 05:35 AM   #31
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by Gost22 View Post
Please be more specific your offer for circuit or schematic to solve the problem.
thank you!
Which problem: to make an amp that works like non-linear attenuator?
__________________
"Our youth [...] have bad manners, contempt for authority; they show disrespect for their elders, contradict their parents, [...] and tyrannize their teachers. -- Plato, 447-367 BCE
  Reply With Quote
Old 26th December 2012, 06:10 AM   #32
diyAudio Member
 
soulmerchant's Avatar
 
Join Date: Sep 2006
Location: in the air
Quote:
Originally Posted by Gost22 View Post
Please be more specific your offer for circuit or schematic to solve the problem.
thank you!
As Kevinkr noted.

His Master's Noise: A Thoroughly Modern Tube Phono Preamp

This is a good thread to start with.
  Reply With Quote
Old 26th December 2012, 06:40 AM   #33
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
Not that I feel obliged to solve your problem.
But just for my own documentation.


Patrick

.
Attached Files
File Type: pdf 2V CCS Public 121226.pdf (316.7 KB, 95 views)
__________________
xen-audio.com
  Reply With Quote
Old 26th December 2012, 09:16 AM   #34
Gost22 is offline Gost22  Bolivia
Banned
 
Join Date: Sep 2012
Location: San Ignatio de Velasco
What's wrong with this solution for the BS170?
  Reply With Quote
Old 9th January 2013, 02:51 PM   #35
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by Gost22 View Post
Hi all!
How about something like this for source constant current at the cathode?
Or you can offer something better.
thank you!
I'm not a tube guy, but it seems to me that with a CCS in the cathode, there will be no signal current through the tube and hence no output signal on the plate.
Is that what is wanted??

jan
__________________
Never explain - your friends don't need it and your enemies won't believe you anyway - E. Hubbart
Check out Linear Audio Vol 7
!
  Reply With Quote
Old 9th January 2013, 04:22 PM   #36
GoatGuy is offline GoatGuy  United States
diyAudio Member
 
Join Date: Dec 2012
Location: SF Bay Area
Default Simple R:2R divider does the trick.

This solves the problem - while maintaining the elegance of a constant-current device, allowing the cathode to take on whatever value (voltage bias) necessary for the tube's nominal operation. A couple of resistors in a voltage-divider orientation and a low bias-point JFET get the job done, for maybe less than a dollar.
Attached Images
File Type: png biaspoint130109a.png (8.8 KB, 110 views)
  Reply With Quote
Old 9th January 2013, 09:15 PM   #37
Ketje is offline Ketje  Belgium
diyAudio Member
 
Join Date: Dec 2012
Location: Flanders
How about like this
Mona
Attached Images
File Type: jpg Icon.JPG (43.3 KB, 97 views)
  Reply With Quote
Old 9th January 2013, 10:06 PM   #38
GoatGuy is offline GoatGuy  United States
diyAudio Member
 
Join Date: Dec 2012
Location: SF Bay Area
Quote:
Originally Posted by Ketje View Post
How about like this
Mona
That one's perfectly workable as well ... with the exception that it needs the cathode-side NPN bypassed to become a constant-current constant voltage power supply as well (in DC), and a variable current, constant voltage supply in the A/C domain.

GoatGuy
  Reply With Quote
Old 10th January 2013, 02:25 AM   #39
Gost22 is offline Gost22  Bolivia
Banned
 
Join Date: Sep 2012
Location: San Ignatio de Velasco
Hi all!
What is a better solution (see graph)
I go with the anode resistor Ra=10k (+B=170V) and cathodic current of 7.6mA and the anode resistor Ra=8K2 (+B=150V) and cathodic current of 7mA.
What is the better of these two solutions for cathodic current of 7.6mA.
What do I get with this solution is better than GoatGuy or Ketje, or go with the cathode resistor Rk=263R for Ik=7.6mA (Rk=286R for Ik=7mA)?
Thank you for your cooperation.
Cheers!
Attached Images
File Type: jpg Gapfik-1.jpg (63.8 KB, 79 views)

Last edited by Gost22; 10th January 2013 at 02:29 AM.
  Reply With Quote
Old 10th January 2013, 03:29 PM   #40
GoatGuy is offline GoatGuy  United States
diyAudio Member
 
Join Date: Dec 2012
Location: SF Bay Area
Quote:
Originally Posted by Gost22 View Post
Hi all!
What is a better solution (see graph)
I go with the anode resistor Ra=10k (+B=170V) and cathodic current of 7.6mA and the anode resistor Ra=8K2 (+B=150V) and cathodic current of 7mA.
What is the better of these two solutions for cathodic current of 7.6mA.
What do I get with this solution is better than GoatGuy or Ketje, or go with the cathode resistor Rk=263R for Ik=7.6mA (Rk=286R for Ik=7mA)?
Thank you for your cooperation.
Cheers!
Hmmm... i think your trying to ask "which is better", without having a sense of "what I am trying to accomplish" with the amplifier stage!

Its REAL simple... if you are trying to INCREASE gain, you use higher resistor values, and higher voltages in the power supply. It has long been forgotten, but the "reason" we use the values that are common-and-popular ... is because in the old days, resistors were expensive, wickedly so ... and therefore within the limits of power dissipation and safe circuit operation (all the capacitors blow if too high voltages are used, and the tube "fades to death", or has its heater fail) ... so its all a compromise.

The DESIGN POINT (typically, though not always) for a non-output amplification stage is this: the plate voltage should be far enough below the supply voltage so that the very widest voltage-swings expected ("designed for") the input, on amplification, result in a clean full-range waveform on the output. Unless you're designing (intentionally) a fuzz box or guitar-amplifier 'coloration stage', then for HiFi audio, lower amplification, more linear operation, closer to the "midpoint" of the V+ supply ... applies.

V+ = 150 and Rplate = 8.2 kohms will not be significantly different (except for gain) over V+ = 170V and Rplate = 10K ... -0.81 db, when you take the effect on mu and operating point into effect.

GoatGuy
  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
Source for current Sony DVD Schematic? moray james Digital Source 0 9th October 2010 06:55 AM
Source for 1.5mA Constant Current Diode in UK / EU? thermionic Parts 4 29th October 2009 09:34 PM
EL84 driver tube, with less than 5mA current then_dude Tubes / Valves 21 4th December 2007 07:44 PM
Constant Current Source Circuit mrfeedback Solid State 8 22nd April 2002 05:07 PM


New To Site? Need Help?

All times are GMT. The time now is 11:44 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