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From: Joel Koltner on 11 Aug 2010 14:25
"Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote in message
news:2RB8o.5066$Yn5.1997(a)en-nntp-14.dc1.easynews.com...
> Have you tried it with any, e.g., 0805 100nH or smaller inductors? These
> often have markedly difference impedances at, e.g., the VHF or UHF
> frequencies you'd typically use them at than the audio or LF frequencies
> that most testers use

^^^ What I really mean here is "markedly different impedance than jwL alone
would suggest" -- that is, the losses (particularly with ferrites) become
significant as do parasitics as you're approaching self-resonance.

From: petrus bitbyter on 11 Aug 2010 19:18

"Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> schreef in bericht
news:i3ucfp$tsq$1(a)news.albasani.net...
>
> A cheap (< 10 $) very accurate LC meter with RS232 interface.
> http://panteltje.com/panteltje/pic/lc_pic/
>
> All credit goes to somebody else (actually a lot of people) for this
> design.
> I merely simplified it some more :-)
> It seems to be very accurate, and is most useful if you are winding your
> own inductors
> or working with RF and extremely small capacitors, a few pF is no problem
> for this.
> It cancels out any lead capacitance in your test leads...
> Have fun :-)
>
>

FAIK the original idee was from AADE (Almost All Digital Electronics). They
still have a version IIB for sale and claims the copyright of his pcb design
and PIC program. Look at:
http://www.aade.com/index.html
for more about it.

Others build similar circuits based upon this meter and made some
improvements as well. I found them in English and in German on several
places on the net.

The one I build was from Phil Rice
http://ironbark.bendigo.latrobe.edu.au/~rice/
and worked pretty well. Nevertheless measuring coils often did not gave the
expected results. This is caused by the frequency the coil is measured with.
Measuring using different frequencies leads to different values. Coils with
a ferrite core vary more then air coils. So though the meter is very usefull
to me, for accurate measuring of a coil I have to measure it with the
frequency which with I want to use it.

petrus bitbyter


From: mike on 12 Aug 2010 04:05
Jan Panteltje wrote:
> A cheap (< 10 $) very accurate LC meter with RS232 interface.
> http://panteltje.com/panteltje/pic/lc_pic/
>
> All credit goes to somebody else (actually a lot of people) for this design.
> I merely simplified it some more :-)
> It seems to be very accurate, and is most useful if you are winding your own inductors
> or working with RF and extremely small capacitors, a few pF is no problem for this.
> It cancels out any lead capacitance in your test leads...
> Have fun :-)
>
>
Looks like an excellent use for all those Palm Pilots in the junk box.
From: Jan Panteltje on 12 Aug 2010 06:46
On a sunny day (Wed, 11 Aug 2010 11:25:41 -0700) it happened "Joel Koltner"
<zapwireDASHgroups(a)yahoo.com> wrote in
<HWB8o.11244$De6.4226(a)en-nntp-01.dc1.easynews.com>:

>"Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote in message
>news:2RB8o.5066$Yn5.1997(a)en-nntp-14.dc1.easynews.com...
>> Have you tried it with any, e.g., 0805 100nH or smaller inductors? These
>> often have markedly difference impedances at, e.g., the VHF or UHF
>> frequencies you'd typically use them at than the audio or LF frequencies
>> that most testers use
>
>^^^ What I really mean here is "markedly different impedance than jwL alone
>would suggest" -- that is, the losses (particularly with ferrites) become
>significant as do parasitics as you're approaching self-resonance.

It is a good question, and I thought about it all night.
I decided that a 'lossy' core should show up as a series R, so jwl + R,
and was curious what would happen.
So I measured some 33 uH coil, it showed 35 uH, then added 10 Ohm in series, and
it showed 39 uH.
LOL
Now these film resistors are sometimes 'wound' with a spiral, but I dunno if this one is.
Of course 10 Ohm is a ridiculous R for a coil of so few turns.

If the ferrite you are referring to causes a complex impedance, then anything can happen.
So I decided to measure some small coils with ferrite adjustable cores,
some from an old UHF + VHF TV tuner.
It measures these no problem, and the values make sense.
I do not know the exact values as these tings are adjustable anyways,
but great to make some tuned circuits that are at least close to the frequency you want.
I also measured some toroids, and that works OK too,
but the max 10 mH is easily exceeded, I measured up to 33 mH, and that seems OK,
(L should go up as square of the number of turns), but higher then 33 mH
is out of range, and 1 uF is out of range too, 220 nF worked OK.

I will probably test some more coils, the thing is very useful for me,
often switchers require 100 uH, 47 uH, etc, and it is very accurate in that range,
you can just wind your own coils.
And that is what I build it for.
Also fun is that I took a 20 cm piece of wire, measured its inductance,
then turned into a loop or 6, and measured it again.
By pressing the loops together you can tune the inductance.
You could put your lossy core in it and see what happens.
Any 2 meter amateur or even if you ever build a FM or TV tuner, will
recognise my 'tuning' method.
:-)
Finally the BFR96 transistor switch could perhaps be replaced by the proper MOSFET,
this because with Vce zero and transistor off, collector floats,
and the thing behaves like a varicap of a few pF, maybe a high value resistor to + would
keep collector emitter cap low, have to try some things.
From: Jan Panteltje on 12 Aug 2010 07:04
On a sunny day (Thu, 12 Aug 2010 01:18:55 +0200) it happened "petrus bitbyter"
<petrus.bitbyter(a)hotmail.com> wrote in
<4c632fce$0$4526$e4fe514c(a)dreader26.news.xs4all.nl>:

>
>"Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> schreef in bericht
>news:i3ucfp$tsq$1(a)news.albasani.net...
>>
>> A cheap (< 10 $) very accurate LC meter with RS232 interface.
>> http://panteltje.com/panteltje/pic/lc_pic/
>>
>> All credit goes to somebody else (actually a lot of people) for this
>> design.
>> I merely simplified it some more :-)
>> It seems to be very accurate, and is most useful if you are winding your
>> own inductors
>> or working with RF and extremely small capacitors, a few pF is no problem
>> for this.
>> It cancels out any lead capacitance in your test leads...
>> Have fun :-)
>>
>>
>
>FAIK the original idee was from AADE (Almost All Digital Electronics). They
>still have a version IIB for sale and claims the copyright of his pcb design
>and PIC program. Look at:
>http://www.aade.com/index.html

Too bad you cannot patent software :-)
Anyway I upgraded it with RS232, making it possible to for examle do a curve of a varicap
on the PC aitomatically with even the soundcard output as drive voltage (or a separate ADC),
so it is a new design.
Also you cannot patent math. This is just basic electronics, if you want
electronics in BASIC, or whatever.
But theirs has a larger L range, and a larger price (129$!!!!!!!!).
I just saved 110 $ LOL.

I think the RS232 option is cool, I did an RS232 frequency counter in a D connector shell too:
http://panteltje.com/panteltje/pic/freq_pic/


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