Measuring small inductances
 

Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

Thanks,

p.
--

The BBC: Licensed at public expense to spread lies.

"Paul Burridge" wrote in message
...
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

www.google.com

"Paul Burridge" wrote in message
...
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

www.google.com

"Paul Burridge" wrote in message
...
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

If you have a signal generator you can connect them to a suitable capacitor
and measure the resonant frequency.

Leon

"Paul Burridge" wrote in message
...
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

If you have a signal generator you can connect them to a suitable capacitor
and measure the resonant frequency.

Leon

On Mon, 15 Mar 2004 12:48:43 -0000, Leon Heller wrote:

"Paul Burridge" wrote in message
...
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

If you have a signal generator you can connect them to a suitable capacitor
and measure the resonant frequency.

Leon

Nyuk, nyuk, nyuk. I bet if he had a signal generator, he wouldn't be
looking for inductors to shotgun that multiplier :) In fact, he
wouln't even be building a multiplier.
--
Best Regards,
Mike

On Mon, 15 Mar 2004 12:48:43 -0000, Leon Heller wrote:

"Paul Burridge" wrote in message
...
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

If you have a signal generator you can connect them to a suitable capacitor
and measure the resonant frequency.

Leon

Nyuk, nyuk, nyuk. I bet if he had a signal generator, he wouldn't be
looking for inductors to shotgun that multiplier :) In fact, he
wouln't even be building a multiplier.
--
Best Regards,
Mike

On Mon, 15 Mar 2004 12:48:43 -0000, "Leon Heller"
wrote:


"Paul Burridge" wrote in message
.. .
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

If you have a signal generator you can connect them to a suitable capacitor
and measure the resonant frequency.

Hi Leon,

That's what I have been doing, in fact. It's just I'd prefer to have a
more convenient, portable method to get instant read-outs of coil
values...
--

The BBC: Licensed at public expense to spread lies.

On Mon, 15 Mar 2004 12:48:43 -0000, "Leon Heller"
wrote:


"Paul Burridge" wrote in message
.. .
Hi all,

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

If you have a signal generator you can connect them to a suitable capacitor
and measure the resonant frequency.

Hi Leon,

That's what I have been doing, in fact. It's just I'd prefer to have a
more convenient, portable method to get instant read-outs of coil
values...
--

The BBC: Licensed at public expense to spread lies.

"Bill Turner" wrote in message
...
On Mon, 15 Mar 2004 10:46:53 +0000, Paul Burridge
wrote:

I've got quite a huge stash of inductors in my parts bin. The colour
codes don't always seem to relate to the values I've been able to
measure, with my multi-function DVM, however, and I can't accurately
measure any inductor about 10uH. Is there a circuit anywhere that
would enable me to get a reasonably accurate idea of the values I've
got down to say 100nH or thereabouts?

__________________________________________________ _______

I'd recommend a grid dip meter and a known capacitor, but be sure to
make the test at a frequency well below the self resonant frequency of
the inductor alone.

Another thing to be wary of: Some inductors are wound on a resistor to
reduce the Q for a specific purpose. Be suspicious of any which have an
unusually broad dip.

--
Bill, W6WRT
QSLs via LoTW


This is what I do; it works well even on my questionable dip meter.

Google for "LCR" meter; see what you come up with (mostly high $
instruments, probably).