measuring output transformer inductance? - diyAudio
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 27th September 2009, 08:16 PM   #1
diyAudio Member
 
Join Date: Feb 2008
Location: Niederösterreich
Default measuring output transformer inductance?

So I am attempting measuring inductance on a 5k to 8ohm single ended output transformer with an LCR meter, Should i load the secondary with an 8 ohm resistor or leave it open? thanks everyone.
  Reply With Quote
Old 27th September 2009, 09:30 PM   #2
diyAudio Member
 
Shoog's Avatar
 
Join Date: Aug 2002
Location: Eire
Any reading would be meaningless unless it has the standing DC current going through it. Without this the reading will b e very high.

Shoog
  Reply With Quote
Old 27th September 2009, 09:49 PM   #3
Yvesm is offline Yvesm  France
diyAudio Member
 
Yvesm's Avatar
 
Join Date: Jul 2004
Location: Ardeche
Quote:
Originally Posted by Shoog View Post
Any reading would be meaningless unless it has the standing DC current going through it. Without this the reading will b e very high.

Shoog
Yes . . . or very low Iron permeability is level sensitive.
  Reply With Quote
Old 27th September 2009, 09:57 PM   #4
diyAudio Member
 
Join Date: Feb 2005
Location: Gelderland
and, it depends which inductance; leakage inductance, afaik short the secondary.

primary inductance, secondary open. but i never tried measuring inductance yet though.
  Reply With Quote
Old 28th September 2009, 04:01 AM   #5
disco is offline disco  Netherlands
diyAudio Member
 
disco's Avatar
 
Join Date: Apr 2006
Location: Holland
Took measurements with an tubed bridge last week and got almost identical readings using 40mA bias and no bias current. This bridge uses a transformer to compare (unknown) impedance to a known.
__________________
jaap
  Reply With Quote
Old 28th September 2009, 04:47 AM   #6
BudP is offline BudP  United States
diyAudio Member
 
BudP's Avatar
 
Join Date: Feb 2007
Location: upper left crust, united snakes
If you use a standard 1vac @ 120 Hz inductance bridge with a SE opt you should know how much DC current the transformer is designed for.

Actual working inductance, with 20 to 40 ma flowing through an appropriate gap, will be approximately twice the rest value (1 vac @ 120 Hz is a rest condition for OPT's. For a PP OPT you can count on about 10 times of this rest inductance.

If the SE OPT is designed for even higher current, 60 to 180 ma, the gap will keep the working inductance to about 1.3 times the rest voltage. Larger gaps than this (physical gap of .015 for E/I or .030 for C Core) and currents out to 320 ma DC, will give a flat inductance out to saturation, from rest conditions.

Bud
  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
measuring crossover inductance, removing winds pjpoes Multi-Way 6 4th April 2007 12:44 AM
Measuring voice-coil self-inductance Klimon Multi-Way 4 19th November 2006 01:23 PM
Weird idea: measuring inductance with a gyrator? DaBit Power Supplies 3 25th January 2006 06:52 AM
measuring the power choke inductance confusion MaciekP Tubes / Valves 5 12th January 2005 12:41 AM


New To Site? Need Help?

All times are GMT. The time now is 03:33 AM.


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