PSU id and help (psu designer ii) - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs 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

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 27th January 2013, 05:11 PM   #11
DF96 is offline DF96  England
diyAudio Member
Join Date: May 2007
That may be a reasonable estimate. You can calculate quiescent current by using Ohm's Law on the cathode resistors. A typical push-pull Class A output will increase its current draw by 10-20% at full output, but that will only be on music peaks so can almost be ignored. Class B will increase more, of course.

A design should say what current it draws. The designer must know, because it is part of the design process.
  Reply With Quote
Old 27th January 2013, 05:21 PM   #12
diyAudio Member
kstagger's Avatar
Join Date: Dec 2003
Location: Grand Rapids
with PSUD2, instead of an end resistor, you can use a constant current load. It's much handier than a final resistor - especially if you really do know what the "average" mA will be. Obviously easier with a Class A circuit.
  Reply With Quote
Old 27th January 2013, 06:28 PM   #13
surfstu is offline surfstu  United Kingdom
diyAudio Member
Join Date: Nov 2008
Location: London
Great guys thanks...

So for the circuit posted below I can assume that V across the cathode of final stage is 10.5 V and the cathode R is 390ohms...

Therefore I = 10.5 / 390 = 0.0269 or 27mA

This is the idle current which would be the same as the quiessent current seeing as this amp operates mainly in class A (is this correct?)

and.... I,m still trying to figure out how the first stage only draws around 1mA and has a constant current source to determine this...

my limited background in physics always taught me that the current was the same for the entire circuit?
Attached Images
File Type: jpg giantkiller-gnfb.jpg (137.6 KB, 40 views)
  Reply With Quote
Old 28th January 2013, 07:18 PM   #14
surfstu is offline surfstu  United Kingdom
diyAudio Member
Join Date: Nov 2008
Location: London
Default Source resistance calculated 1

Ok, thanks to all here - I'm making headway!

primary resistance = 9ohms

secondary resistance = 63ohms (CT to Sec)

Source resistance = (primary resistance / (Vpri/Vsec)2) + Secondary resistance

Vpri = 230
Vsec = 270

(Vpri/Vsec)2 = 0.726

therefore Source resistance = 75.3ohms
  Reply With Quote


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
PSU Designer II question ccschua Tubes / Valves 2 20th June 2009 03:40 PM
Is PSU Designer II correct? zxx123 Tubes / Valves 7 20th January 2008 05:21 PM
Duncan PSU Designer II MattM Pass Labs 2 2nd February 2005 08:24 AM
Need some help with PSU Designer II Bricolo Parts 12 14th November 2002 06:42 PM

New To Site? Need Help?

All times are GMT. The time now is 10:45 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2