Need for semiconductors testing/matching board? - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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 13th September 2015, 10:52 AM   #1
jps1964 is offline jps1964  Germany
diyAudio Member
 
Join Date: Sep 2013
Location: Eisingen
Default Need for semiconductors testing/matching board?

Many people are spending a lot of time by matching semiconductors!

My question, is there a real need for a testing/matching board?

If yes, then supply the schematics, I will spend time for layouting, then a GB.
  Reply With Quote
Old 13th September 2015, 11:26 AM   #2
diyAudio Member
 
JonSnell Electronic's Avatar
 
Join Date: Dec 2012
Location: The Jurassic Coast, England. GB
Send a message via Skype™ to JonSnell Electronic
Just use a standard DVM with a transistor tester on it. Most of the matching is already done by the manufacturer putting Hfe codes on the transistors. In the front end of an amplifier, I would bother to match the differential pair for Hfe and Vbe but otherwise as long as there is enough Hfe in the drivers and output stages, the negative feedback takes care of the rest.
__________________
Support for Flying Mole Class D, Allen & Heath, Valve amps, older designs & 2CVs. www.jonsnell.co.uk
  Reply With Quote
Old 15th September 2015, 05:58 PM   #3
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Paralleled transistors need some selection/matching, if you need them to operate at similar temperatures.
__________________
regards Andrew T.
Sent from my desktop computer using a keyboard
  Reply With Quote
Old 15th September 2015, 06:07 PM   #4
diyAudio Member
 
Join Date: May 2011
Location: Silicon Valley
Maybe the Original Poster and/or the participants in THIS THREAD might offer some advice.
  Reply With Quote
Old 16th September 2015, 02:25 PM   #5
diyAudio Member
 
2 picoDumbs's Avatar
 
Join Date: Sep 2013
Blog Entries: 2
Quote:
Originally Posted by JonSnell Electronic View Post
Just use a standard DVM with a transistor tester on it. Most of the matching is already done by the manufacturer putting Hfe codes on the transistors. In the front end of an amplifier, I would bother to match the differential pair for Hfe and Vbe but otherwise as long as there is enough Hfe in the drivers and output stages, the negative feedback takes care of the rest.
Most people in Pass Labs forum are interested in mosfets not bipolar transistors
__________________
"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass
  Reply With Quote
Old 16th September 2015, 02:26 PM   #6
diyAudio Member
 
2 picoDumbs's Avatar
 
Join Date: Sep 2013
Blog Entries: 2
Quote:
Originally Posted by jps1964 View Post
Many people are spending a lot of time by matching semiconductors!

My question, is there a real need for a testing/matching board?

If yes, then supply the schematics, I will spend time for layouting, then a GB.
Nelson wrote an article on testing mosfets with schematics.
__________________
"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass
  Reply With Quote
Old 16th September 2015, 02:41 PM   #7
jps1964 is offline jps1964  Germany
diyAudio Member
 
Join Date: Sep 2013
Location: Eisingen
@2 picoDumbs

I know this article. I want to catch all existing to go eggs laying full-cream milking sow!
  Reply With Quote
Old 16th September 2015, 02:47 PM   #8
diyAudio Member
 
2 picoDumbs's Avatar
 
Join Date: Sep 2013
Blog Entries: 2
A curve tracer as a separate project may also be of interest.
__________________
"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass
  Reply With Quote
Old 16th September 2015, 02:55 PM   #9
EUVL is offline EUVL  Europe
diyAudio Member
 
Join Date: Oct 2003
A matching device or curve tracer is of no use if you don't have enough devices to match from.
And since this is the biggest problem since Toshiba stopped essentially all analogue discrete devices, your best bet is to buy them pre-matched.

For decent pairing you need a pool of minimum 25~50.
And you will still have a high reject rate (our recent experience with FQP3N30/3P20).
We consider 200~1000 devices as normal.
So if you can solve the device sourcing problem, you can think about equipment.

Until then.


Cheers,
Patrick

PS
As have been discussed elsewhere there is a difference between matching for equal current sharing or distortion cancellation.
You only need a curve tracer for the latter.
__________________
xen-audio.com

Last edited by EUVL; 16th September 2015 at 02:57 PM.
  Reply With Quote
Old 16th September 2015, 03:04 PM   #10
diyAudio Member
 
2 picoDumbs's Avatar
 
Join Date: Sep 2013
Blog Entries: 2
Quote:
Originally Posted by EUVL View Post
A matching device or curve tracer is of no use if you don't have enough devices to match from.
And since this is the biggest problem since Toshiba stopped essentially all analogue discrete devices, your best bet is to buy them pre-matched.

For decent pairing you need a pool of minimum 25~50.
And you will still have a high reject rate (our recent experience with FQP3N30/3P20).
We consider 200~1000 devices as normal.
So if you can solve the device sourcing problem, you can think about equipment.

Until then.


Cheers,
Patrick

PS
As have been discussed elsewhere there is a difference between matching for equal current sharing or distortion cancellation.
You only need a curve tracer for the latter.
Who says we don't have enough devices.
I have 300 each of irfp240/9240
200 each of exicon laterals
Besides that it's not just about matching it's about choosing devices with desirable properties.
__________________
"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass
  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
The paradise sound of es9018 testing board bin138 Vendor's Bazaar 8 7th March 2012 01:32 AM
A/B testing board for high power amps udailey Class D 6 1st October 2011 09:59 PM
Speaker Testing Jig PC board / Kit MJL21193 Swap Meet 30 17th October 2010 02:19 PM
Peavey 1.3K amp smoked... board testing soccerman58 Solid State 2 30th August 2008 01:11 AM
Testing Stepper Motor And Driver Board artb Parts 0 1st July 2006 10:24 AM


New To Site? Need Help?

All times are GMT. The time now is 11:25 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki