Weird idea: measuring inductance with a gyrator? - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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 24th January 2006, 09:25 PM   #1
DaBit is offline DaBit  Netherlands
diyAudio Member
Join Date: Aug 2005
Send a message via ICQ to DaBit
Default Weird idea: measuring inductance with a gyrator?

I have a weird idea. Many multimeters can measure capacitance, but only some can measure inductance.

Now what about using a gyrator (opamp circuit to 'reverse' impedance) to transform the inductance to a capacitance, and measuring that?

Anyone ever tried something like that?
  Reply With Quote
Old 24th January 2006, 10:12 PM   #2
diyAudio Member
darkfenriz's Avatar
Join Date: Jun 2004
Location: Warsaw
If you have in mind the two op-amp gyrator for "the art of electronics", then I would say it is not doable.
As far as I remember the impedance 'to be inverted' is in negative feedback loop of one of op-amps. Inductor in feedback loop means instability because of total phase shift of 180 by inductor together with frequency compensation.
Other ways, with one op-amp assume series resistance I think, but I'm no sure about this.
  Reply With Quote
Old 25th January 2006, 01:37 AM   #3
diyAudio Member
jackinnj's Avatar
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
I just cut and paste this every time I see someone trying to measure impedance, capacitance etc., the hard way:

The sound card impedance tester is here Post #1
discussed in the most recent edition of the ham radio magazine QST (with a more scientific discussion in QEX it's companion mag.)

The LMS test set uses a dual opamp to compare the voltage drop across an unknown impedance and an acurately known resistor. It is remarkably simple.

You can test inductors, capacitors, transformers, negative impedances, etc.

A PDF of the QEX article is available at

the code can be downloaded at
just look about 1/3 down the page

you may need to run
VBRun60sp5.exe (availbable at Microsoft Downloads) if you get the error message "Required DLL file MSVBVM60.DLL was not found"


edit: I should have credited the author of the article -- Dr. George Steber, WB9LVI, Prof. Emeritus of EE at the University of Wisconsin, Milwaukee.
  Reply With Quote
Old 25th January 2006, 05:52 AM   #4
DaBit is offline DaBit  Netherlands
diyAudio Member
Join Date: Aug 2005
Send a message via ICQ to DaBit
Nice article. Worth a try. Thanks for pointing it out.
  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
41hz Amp4 - Telling MOSFETS apart, and measuring Inductance without a metre Peteruk Parts 2 27th July 2007 12:58 PM
measuring crossover inductance, removing winds pjpoes Multi-Way 6 3rd April 2007 11:44 PM
Measuring voice-coil self-inductance Klimon Multi-Way 4 19th November 2006 12:23 PM
measuring the power choke inductance confusion MaciekP Tubes / Valves 5 11th January 2005 11:41 PM

New To Site? Need Help?

All times are GMT. The time now is 02:36 AM.

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