Having trouble with F3 current source - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 23rd August 2008, 06:34 AM   #1
diyAudio Member
 
Join Date: Mar 2002
Location: n/a
Default Having trouble with F3 current source

Hey all.

I'm currently applying power to my F3 boards, and I'm having trouble setting the current source. I understand that the percentage is supposed to be the ratio of current through the output resistor to the ratio through the aleph resitors.

So what I've got, I measuring the AC voltage across resistors R6/R7/R8 (which make 0.4 ohm), and the output resistor R9 (0.47 ohm).

Here's what I get :

drop across r6/r7/r8 = 0.206 V
0.4 / 0.206 = 1.94 A

drop across r9 = 0.35 V
0.47 / 0.35 = 1.35 A

1.94/1.35 *100 = 140 % !!!!!!!!

That's not right ... No matter what I set P2 to, the current through the aleph resistors is alway greater than what's going though the output resistor.

Any idea where I may have gone wrong ?
  Reply With Quote
Old 23rd August 2008, 07:10 AM   #2
BDP is offline BDP  United States
diyAudio Member
 
Join Date: Apr 2002
Location: SE Washington State
Should'nt the voltage drop across R6,7,8 be .66 volts, the emitter base junction of Q4?
  Reply With Quote
Old 23rd August 2008, 07:27 AM   #3
diyAudio Member
 
Join Date: Mar 2002
Location: n/a
Sorry everyone.

Please delete this thread, or make it a sticky, as a permanent reminder of Ohm's law.

My calcs should have been along the lines of 0.204 (V)/0.4 (ohms), rather than 0.4 / .204 .....

*smacks head*
  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
Aleph-type current source, but source follower this time tschrama Pass Labs 4 29th July 2005 01:55 PM
having trouble setting quiesent current? tinkerbell Solid State 35 12th April 2005 12:34 AM
Source follower electret mike -> use with current source? capslock Solid State 1 28th February 2003 01:54 PM
R21? and Current Source AC Current Gain macka Pass Labs 9 20th May 2002 09:58 PM
Current source for BOZ harvardian Pass Labs 49 6th May 2002 03:44 PM


New To Site? Need Help?

All times are GMT. The time now is 02:18 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