I'd like to build a variable inductor with what I have around my shop (lots
of bits n' pieces, but no cores). I need it to work in the area of 20-30 mH,
1A, 25-30 KHz.

Is this something do-able? Is there something available off-the-shelf?

Suggestions of how to go about it would be greatly appreciated.

FBt

On Mon, 31 Mar 2008 14:11:22 -0700, Esther & Fester Bestertester wrote:

I'd like to build a variable inductor with what I have around my shop (lots
of bits n' pieces, but no cores). I need it to work in the area of 20-30 mH,
1A, 25-30 KHz.

Is this something do-able? Is there something available off-the-shelf?

Suggestions of how to go about it would be greatly appreciated.

FBt

Hi,

You need it to handle 1A of current down there? You must be a VLFer.

No cores is right, it will probably saturate and make for a BBQ. We are
talking a BIG air core inductor here. A variometer might be your best bet
for variable inductance with those specs. Give that a Google.

Cheers,
__
Gregg

A variometer might be your best bet
for variable inductance with those specs. Give that a Google.

Thanks for the pointer, Gregg. Excellent information available, once one
knows the right terminology. :-)

FBt

You need it to handle 1A of current down there? You must be a VLFer.

No cores is right, it will probably saturate and make for a BBQ. We are
talking a BIG air core inductor here.

OK, how about if I lower the specs to ~0.5A, or even less. How can I
construct a variable inductor 0 to 10 mHy (or more)?

Thank,
FBt

On Wed, 2 Apr 2008 23:00:33 -0700, Anon bozo wrote:
You need it to handle 1A of current down there? You must be a VLFer.

No cores is right, it will probably saturate and make for a BBQ. We are
talking a BIG air core inductor here.

OK, how about if I lower the specs to ~0.5A, or even less. How can I
construct a variable inductor 0 to 10 mHy (or more)?

Maybe a variac? Or, would that be too VVLF? HI!HI!

Jonesy
--
Marvin L Jones | jonz | W3DHJ | linux
38.24N 104.55W | @ config.com | Jonesy | OS/2
*** Killfiling google posts: http://jonz.net/ng.htm

This is the answer:
http://www.qsl.net/in3otd/variodes.html


"Esther & Fester Bestertester" wrote in message
obal.net...
I'd like to build a variable inductor with what I have around my shop
(lots
of bits n' pieces, but no cores). I need it to work in the area of 20-30
mH,
1A, 25-30 KHz.

Is this something do-able? Is there something available off-the-shelf?

Suggestions of how to go about it would be greatly appreciated.

FBt

On Thu, 03 Apr 2008 15:57:08 GMT, JB wrote:
This is the answer:
http://www.qsl.net/in3otd/variodes.html

I like the way the answers are carried out to *thirteen* decimal places!

"Esther & Fester Bestertester" wrote in message
obal.net...
I'd like to build a variable inductor with what I have around my shop
(lots
of bits n' pieces, but no cores). I need it to work in the area of 20-30
mH,
1A, 25-30 KHz.

How about using a very low-ohmic wire-wound pot? OK. Q will not be
brilliant, but in these applications you may get away with it

Wim

Esther & Fester Bestertester wrote:
I'd like to build a variable inductor with what I have around my shop (lots
of bits n' pieces, but no cores). I need it to work in the area of 20-30 mH,
1A, 25-30 KHz.

Is this something do-able? Is there something available off-the-shelf?

Suggestions of how to go about it would be greatly appreciated.

FBt

Take a transformer with sufficient mH, and use a constant current
on one of the unused windings to saturate the iron core to reduce
the mH rating.

I never measured a Variac before. Might be higher than you were looking
for. That's variable for sure. A good thing to have around the shop.

"JB" wrote in message
news77Jj.18730$bC6.7879@trnddc08...
This is the answer:
http://www.qsl.net/in3otd/variodes.html


"Esther & Fester Bestertester" wrote in message
obal.net...
I'd like to build a variable inductor with what I have around my shop
(lots
of bits n' pieces, but no cores). I need it to work in the area of 20-30
mH,
1A, 25-30 KHz.

Is this something do-able? Is there something available off-the-shelf?

Suggestions of how to go about it would be greatly appreciated.

FBt