[volt-nuts] Anyone know how to make stable inductors?

[Todd Micallef]

Here is a DIY guide to making some lab standards. It is detailed with some
component values.

http://nopr.niscair.res.in/bitstream/123456789/4848/1/JSIR%2065%286%29%20510-513.pdf

On Wed, Aug 19, 2015 at 8:48 PM, Dave M <dgminala at mediacombb.net> wrote:

> Here's a paragraph from IETLab's web site on how their inductance
> standards are made:
>
> "Each standard inductor is a uniformly wound toroid on a ceramic core. It
> has a negligible external magnetic field and hence essentially no pickup
> from external fields. The inductor is resiliently supported in a mixture of
> ground cork and silica gel, after which the whole assembly is cast with a
> poƫting compound into a cubical aluminum case."
>
> Sounds like their objective is to isolate the winding from as many
> external influences as possible.  Of course, the same couild be said of any
> physical or electrical standard.
>
> Cheers,
> Dave M
>
>
>
>
> Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
>
>> I was looking to make some inductors that I can use as a sanity check
>> for
>> my HP 4284A LCR meter. I don't too much care what their values are,
>> but I want them to be stable with time. Any suggestions about the
>> best way to
>> make or buy them? I'd like values in the range of 1 nH to 100 mH.
>>
>> The LCR meter has 4 terminal Kelvin connections, with 4 x BNC sockets
>> on a 22 mm pitch.
>>
>> The meter is at Keysight at the moment being calibrated, along with a
>> free software upgrade they are kindly providing. So I'd like to
>> measure some inductors when it comes back, and track their values
>> over time, to see if the meter is drifting.
>>
>> The meter covers 20 Hz to 1 MHz, and has a basic uncertainty of
>> 0.05%, so ideally I'd like to keep inductor changes to less than
>> 0.005% over a year, so the inductor is an order of magnitude better
>> than the meter. Maybe that is not practical. As I say, the absolute
>> value is not important, since I only want a comparison.
>>
>> The calibration costs on this meter are not too bad (£207 GBP), but
>> the calibration interval is 6 months, which is a bit annoying. I'd
>> rather not
>> be sending it off every 6 months if I can satisfy to myself it has not
>> drifted too much. Luckily I don't need to satisfy anyone else.
>>
>> Dr. David Kirkby Ph.D CEng MIET
>> Kirkby Microwave Ltd
>> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex,
>> CM3 6DT, UK.
>> Registered in England and Wales, company number 08914892.
>> http://www.kirkbymicrowave.co.uk/
>> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
>>
>
>
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