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From: Grant on 12 Aug 2010 17:59
On Thu, 12 Aug 2010 15:54:19 GMT, Jan Panteltje <pNaonStpealmtje(a)yahoo.com> wrote:

>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.

But you're then plugging rs232 -> USB adapter? So there's 5V at ~500mA
available to play with?

Pop the lid of the serial/USB bridge?

I ordered a couple serial <-> usb bridge kits yesterday, they have the
5V and 3.3V available, as well as modem signals and shutdown option,
and windoze/mac/linux drivers -- I'll report on it when it arrives.

I'm not about to waste time reinventing USB connectivity ;)

Can the reference cap be a higher value? My interest is in larger
inductor values too.

Grant.
From: Uwe Hercksen on 13 Aug 2010 06:11


Jan Panteltje schrieb:

> A cheap (< 10 $) very accurate LC meter with RS232 interface.
> http://panteltje.com/panteltje/pic/lc_pic/

Hello,

if you scan your hand drawn circuit diagrams, an easily readable result
would be nice. Using white papaer and a really black pen would give more
contrast.

Bye

From: John Ferrell on 13 Aug 2010 14:19
You are implying there is something new that replace my Palm Pilot. I
have not found anything yet...

On Thu, 12 Aug 2010 01:05:04 -0700, mike <spamme0(a)go.com> wrote:

>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.
John Ferrell W8CCW
From: Spehro Pefhany on 13 Aug 2010 15:08
On Fri, 13 Aug 2010 14:19:41 -0400, John Ferrell
<jferrell13(a)triad.rr.com> wrote:

>You are implying there is something new that replace my Palm Pilot. I
>have not found anything yet...

No, he's implying that PDAs are only useful as sorta dumb terminals.

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