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From: Hammy on 12 Aug 2010 08:44
On Wed, 11 Aug 2010 11:19:41 -0700, "Joel Koltner"
<zapwireDASHgroups(a)yahoo.com> wrote:

>"Jan Panteltje" <pNaonStpealmtje(a)yahoo.com> wrote in message
>news:i3ucfp$tsq$1(a)news.albasani.net...
>> 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.
>
>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; I usually end up using a network analyzer to take a look at what their
>impedance "really" is.
>
>Definitely a nice little device!

I built this meter up a few years ago and it is useful I did my own
layout and used different components but it is cheap about ten to
fifteen bucks was my total investment including a handheld enclosure
to put it in. Your ? got my curiosity though. I've never used it for
measuring tiny inductances lowest are beads usually they are 4.7uH.
But here is a sampling.

HF INDUCTOR, 680NH, 280mA 5% 650MHZ,0805

http://canada.newark.com/vishay-dale/imc0805err68j01/hf-inductor-680nh-280ma-5-650mhz/dp/53K5159?Ntt=53k5159

Measured 640nH

The lowest I have is a 33nH 0603 and I cant get a reliable reading on
that.

For this 220nH,1008 one I get 260nH

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=PCD1053CT-ND

I tried measuring some 0603 in the 100 to 330nH but with my leads its
pretty difficult. So I guess I'll have to take Digikey's and Newark
word on those ;-).

I mainly use it for smps 4.7uH and up and its always given reasonable
readings..

For a 27mH CMC I GET 26.1mH.

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=495-2775-ND

This is good enough for my needs and beats dropping a couple of grand
on an LC meter.
From: Jan Panteltje on 12 Aug 2010 11:04
On a sunny day (Thu, 12 Aug 2010 08:44:19 -0400) it happened Hammy
<spam(a)spam.com> wrote in <kcp766h4bbe4dpkfrc78fb7bs457vp00m3(a)4ax.com>:

>
>I built this meter up a few years ago and it is useful I did my own
>layout and used different components but it is cheap about ten to
>fifteen bucks was my total investment including a handheld enclosure
>to put it in.

What did you use to switch the reference capacitor,
BJT?
MOSFET?
Relay?
From: Hammy on 12 Aug 2010 11:44
On Thu, 12 Aug 2010 15:04:27 GMT, Jan Panteltje
<pNaonStpealmtje(a)yahoo.com> wrote:

>On a sunny day (Thu, 12 Aug 2010 08:44:19 -0400) it happened Hammy
><spam(a)spam.com> wrote in <kcp766h4bbe4dpkfrc78fb7bs457vp00m3(a)4ax.com>:
>
>>
>>I built this meter up a few years ago and it is useful I did my own
>>layout and used different components but it is cheap about ten to
>>fifteen bucks was my total investment including a handheld enclosure
>>to put it in.
>
>What did you use to switch the reference capacitor,
>BJT?
>MOSFET?
>Relay?


I Used a reed relay.

I was going to use 2n7002 or similar but I thought the drain
capacitance might effect the accuracy.
From: Jan Panteltje on 12 Aug 2010 11:54
On a sunny day (Thu, 12 Aug 2010 11:44:15 -0400) it happened Hammy
<spam(a)spam.com> wrote in <5b5866tetr5sqp3rv2pfd2e1nr79i4voen(a)4ax.com>:

>On Thu, 12 Aug 2010 15:04:27 GMT, Jan Panteltje
><pNaonStpealmtje(a)yahoo.com> wrote:
>
>>On a sunny day (Thu, 12 Aug 2010 08:44:19 -0400) it happened Hammy
>><spam(a)spam.com> wrote in <kcp766h4bbe4dpkfrc78fb7bs457vp00m3(a)4ax.com>:
>>
>>>
>>>I built this meter up a few years ago and it is useful I did my own
>>>layout and used different components but it is cheap about ten to
>>>fifteen bucks was my total investment including a handheld enclosure
>>>to put it in.
>>
>>What did you use to switch the reference capacitor,
>>BJT?
>>MOSFET?
>>Relay?
>
>
>I Used a reed relay.
>
>I was going to use 2n7002 or similar but I thought the drain
>capacitance might effect the accuracy.

Yes, good solution, reeds, but snice I take the power from the RS232 DTR
I think I am limited to less then a few mA...
Maybe I could use a bipolar relay and discharge a cap into it...
Have to think about this.
From: Joel Koltner on 12 Aug 2010 13:50
Thanks Jan -- that's good information!
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