Sensing small inductances

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Microcontroller-based strategies like this work OK for high-Q inductances:

<http://www.pa3fwm.nl/technotes/tn11b.html

But don't work too good for little random-wire very lossy inductances,  
of values around 0.5uH to 5uH, at the lower excitation frequencies that  
microprocessors can easily provide from direct pin-switching system  
clock-derived outputs. e.g. inductaors that have self-resonant  
frequencies in the 100s of MHz.

I was thinking the small inductance could have its effective Q boosted  
via boostrapping, perhaps (I'm kinda down on negative impedance  
circuits, now, you can make some cute circuits with them but they all  
obv. tend towards being unstable and are "fiddly" and I'm uncomfortable  
using them in "real work")

and then you could measure a certain range of small inductances by  
applying a clock to a tank circuit thru a resistor, and putting the  
original clock plus the output from the tank into a phase detector a la  
a PLL and look at the integrated leading or lagging phase "up/down"  
signal to infer the inductance.

It might need little external hardware other than the Q-booster in some  
implementation. Clock out to the tank and leading/lagging phase signal  
back in to the uP to an onboard comparator/phase detector and integrator.

For my particular solution needs whatever form it takes, it would be  
best to trade of absolute accuracy for precision/repeatability.

Re: Sensing small inductances
On a sunny day (Sat, 24 Aug 2019 23:31:00 -0400) it happened bitrex

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 http://panteltje.com/panteltje/pic/lc_pic/


Re: Sensing small inductances
On 8/25/19 1:24 AM, Jan Panteltje wrote:
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+/- 10 nH not quite sufficient +/- 1 would be better, but the  
two-variable, dual-frequency measurement technique I think will help a lot

Re: Sensing small inductances
On 8/25/19 1:24 AM, Jan Panteltje wrote:
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The math is clever, I wonder what would happen if you used a bank of  
Cref capacitors and instead of a two variable, two unknown system you  
used e.g. four measurement frequencies and did the math on a system of  
larger order. would that improve resolution? accuracy? precision?

Re: Sensing small inductances
On Sunday, August 25, 2019 at 4:26:05 PM UTC+10, bitrex wrote:
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You'd end up with an over-determined set of equations and would have to use a least square multi-parameter error minimisng scheme to extract the most likely solutions (and confidence limits). I did that in my Ph.D. project - it should be easier now.

--  
Bill Sloman, Sydney


Re: Sensing small inductances
On 8/25/2019 12:24 AM, Jan Panteltje wrote:
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  Print and put in values.
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                      Mikek


Re: Sensing small inductances
On a sunny day (Sun, 25 Aug 2019 11:07:04 -0500) it happened amdx

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Get a real monitor and /or see an eye doctor.


Re: Sensing small inductances
On Sun, 25 Aug 2019 17:02:59 GMT, Jan Panteltje

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Your schematics are unreadable. I don't even try.


Re: Sensing small inductances
On a sunny day (Sun, 25 Aug 2019 10:17:07 -0700) it happened
snipped-for-privacy@highlandsniptechnology.com wrote in

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You could learn something, but WTF do I care,
I do not use your products.

Re: Sensing small inductances
On 8/25/19 1:34 PM, Jan Panteltje wrote:
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these dudes just being dramatic.

Re: Sensing small inductances
On 8/25/19 1:34 PM, Jan Panteltje wrote:
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engineers looking at schematics like good gracious! why it's just awful!  
/hand to forehead, swoon

I thought women were supposedly the dramatic ones

Re: Sensing small inductances

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I thought engineering drawings were supposed to be clear and precise.
I assume he draws like that on purpose.

ps - your misogyny is apparent again


Re: Sensing small inductances
On 8/25/19 2:59 PM, snipped-for-privacy@highlandsniptechnology.com wrote:
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No, more like my sarcasm. It's not a thing I would say, but it is a  
thing oppressed right-wing minorities like former Google employee James  
Damore would write a whole paper on

Re: Sensing small inductances

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So why did you say it?

You meant it.  

Re: Sensing small inductances
On 8/25/19 6:49 PM, snipped-for-privacy@highlandsniptechnology.com wrote:

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I'll gladly tell my girl friend a right wing engineering professional on  
the internet said I was a misogynist, I expect she'll probably roll her  
eyes and laugh in the way she usually does when from time to time I show  
her some of the right-wing rants that pop up here lol. Hold up I'm gonna  
show her the whole thread right now. brb.

Re: Sensing small inductances
snipped-for-privacy@highlandsniptechnology.com wrote...
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 I'm often curious, but can not read them.  
 Jan, why are they so dark, with such a poor
 contrast ratio?   How do you even do that?


--  
 Thanks,
    - Win

Re: Sensing small inductances
On a sunny day (25 Aug 2019 10:38:32 -0700) it happened Winfield Hill

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I dunno, I have no problem reading those in my browser,
or Linux 'xv' viewer or whatever,

Often I wonder (video is my background) if people even know how to adjust a monitor,
These pictures are of schematics I use to build the stuff,
so 100% of info is there or it would have to be so obvious I omitted it.
I do not sell kits.
All the babble .. read the asm source it clearly shows in ASCII what is connected to what.
If anybody actually builds this thing they can ask.
The explanation text in the link I gave is 100% simple for anybody known in the art,

And if you cannot read it or understand it, so be it,

As to the art, if you cannot read a component value and understand what sort of magnitude say 'resistor' must be there
you need to do more experimenting, not so many silly simulations.

Next somebody will say: 'Oh and I cannot read PIC asm..'
There is no end to not understanding
somebody once wrote something like 'hydrogen is the most present thing in the universe but for stupidity'
 https://quoteinvestigator.com/2014/01/09/hydrogen/
  different versions of it.

I am not referring to you, I know you know the stuff.
Jo.La. has a bunch of payed slaves working out details for him...
 Some other one is into crystal radios and refuses to look up super-heterodyne
even offered me a deal LOL.
No hope there.

Hawaiian War Chant  
 
https://www.youtube.com/watch?v=QY0ThFAp0Bc


:-)

Re: Sensing small inductances
On Sun, 25 Aug 2019 18:18:12 GMT, Jan Panteltje

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Very well paid slaves. We design things together, and we share clear,
precise drawings.  

Each project has a responsible engineer, which is sometimes me,
usually someone else. We create a project folder on a shared server,
where we leave a design notes folder for sharing ideas now, and for
future reference.

Sure, sometimes I get help on my projects, and sometimes I help people
on theirs. It's fun and we all learn stuff.

We also document all breadboards and experiments. Clearly.

You can read your drawings because you are intimately familiar with
them; we aren't and can't.


Re: Sensing small inductances
On 8/25/2019 1:18 PM, Jan Panteltje wrote:
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I doubt you go back to your monitor when you build, you use your paper  
schematic. If you are going to post schematics and we want you to,
why not make them readable by all those people that don't know how to  
adjust their monitors. It's really not hard.
  Is it just that you have had so many people tell you about the quality  
of your schematics that you're not going to let them tell you what to  
do? What, your 13 yrs old.

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You're deflecting, your schematics are hard to read
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Now help me on my inductor ferrite choice! :-)
                      With love, Mikek

Re: Sensing small inductances
On Sun, 25 Aug 2019 18:18:12 GMT, Jan Panteltje

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I definitely not going to set-up my monitor for every odd picture. I
once set it up for color balance and background illumination levels.

Get yourself a decent flatbed scanner and scan it to proper B/W GIF
(not JPEG). Flatbed scanners are available in multifunction printers




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