Schematics of analog LC-meter

[RiffMaster]

Hi
I am looking for a schematic for an Analog L-meter (inductance meter).
Please note that I am not looking for something that use a microcontroler as AADE LC-meter.
I remember that I saw while ago in a magazine an Analog inductance-meter using only a few op-amps and the output was a DC voltage that you can read with a voltmeter (analog or digital).
I found on the net this one, but for some reasons do not function properly for low inductances:
http://www.armory.com/~rstevew/Public/TestEquip/IndMeterAdapter.htm

thanks

 

[Borber]

l-meter

Look at this circuit:
https://www.qsl.net/va3iul/L_meter/L_meter.htm

 

[mayu_wakui]

l meter circuit

hope this helps..

**broken link removed**

 

[RiffMaster]

inductance meter schematic

Hello,
Just to let you know that I’ve tested these circuits and both works okay.
The first one is more stable and I was able to measure a minimum inductance of 10 nano Henry, after calibration. Have better stability probably because is using a crystal oscillator. Instead of 100kHz crystal I used 1MHz divided by 10.
With second circuit I was able to measure a minimum inductance of 1micro Henry.
Regards

 

[Borber]

l meter schematic

Another possibility is this LC meter:
**broken link removed**
It has 1nH resolution.

The advantage of L meter according to my first link is that resistance of inductor has no influence on precision. This is because of quadrature detector it uses.

 

[RiffMaster]

lc meter schematic

Borber,
I know this circuit that is based on AADE design (originally using PIC16C622) and which is working very nice down to 1nH.
But as I said in my first post, for a particular application I was looking for a schematic without microcontroller.
thanks

 

[vaclavp]

l9 meter wiring

I made LC-meter similar to AADE design but I have problem with stability.

I have big frequency swing like modulation or something similar.

Did somebody notice such behaviour ? I tried to change several components but it looks it did not help...

Can somebody help me ?

 

[MikeOhio]

build a simple l-meter

RiffMaster;
You didn't specify what range of measurement you were looking for, but for a design using fixed oscillators, which can certainly be scaled up or down, you might take a look at Monty's website here:
**broken link removed**
Lots of other useful items on his site as well.

Mike

 

[ahmad_abdulghany]

analog inductance meter

Hello,
Just to let you know that I’ve tested these circuits and both works okay.
The first one is more stable and I was able to measure a minimum inductance of 10 nano Henry, after calibration. Have better stability probably because is using a crystal oscillator. Instead of 100kHz crystal I used 1MHz divided by 10.
With second circuit I was able to measure a minimum inductance of 1micro Henry.
Regards

Hello RiffMaster:
As you did the above two circuits, so can you please tell me how did you get (or make) the 6-way swich in the first schematic,
Thanks,
Ahmad,

 

[RiffMaster]

measure nanohenry

Hello RiffMaster:
As you did the above two circuits, so can you please tell me how did you get (or make) the 6-way swich in the first schematic,
Thanks,
Ahmad,[/quote]

I was interested to build the circuit only for one scale (the lowest one), so I don’t use a multi-position connector.
Probably could be used any oscilloscope type connector, that have two slots and multi-positions.

 

[ahmad_abdulghany]

nanohenry measure

can you please tell me how did you get (or make) the 6-way swich in the first schematic,
- Probably could be used any oscilloscope type connector, that have two slots and multi-positions.

Okay, then how can what's the Oscilloscope type connector, and where can i get it?
Or how can I use another thing as an equivalent to that connector?

 

[RiffMaster]

inductance meter with 1 nh resolution

Something like this rotary switch:
https://www.circuitspecialists.com/products/full/200.jpg