Variable inductor question

[robot gigante]

Hello tech slutz,

I came across an ancient 'variable inductor' in an ammo can size box in a junk store, and I was wondering if it was a good idea to try wiring it into some basic audio circuit and if so? I don't know enough about this stuff to know if it would be worth the effort, but I do know a couple people who are OK at putting things together.

Sorry if this is a stupid question.

It looks impressive enough ('battleship' dial, wood trim), if I did buy it I could always not hook it up to anything, and joke around with clients I guess.

Thoughts?

[S2udio]

A Guess would be a variac........
Useless unless the lights in your studio need dimming !
Picture.......... or is this a guessing game ?

[mjrippe]

A Variac is a variable transformer. If this is actually an inductor (is it labeled as such?) you could probably make it into a variable filter of some sort.

[S2udio]

Originally Posted by mjrippe

A Variac is a variable transformer.

I am quite aware of that fact....
But lets guess

[robot gigante]

Originally Posted by mjrippe

A Variac is a variable transformer. If this is actually an inductor (is it labeled as such?) you could probably make it into a variable filter of some sort.

I had thought it might be a variac when first looking at it, but it had a plaque on it that said variable inductor.

I had thoughts of making it into a variable filter or running signal through it for saturation or something. I have never seen an inductor this monstrous before for one thing.

Unfortunately I didn't take a pic. Picture a box like an ammo can with a dial and old school industrial connectors, passive, no psu. That's about it.

[S2udio]

Originally Posted by mjrippe

you could probably make it into a variable filter of some sort.

I very much doubt it..
Assumption never pays off !
IMHO your wasting your time

[Matt Syson]

Hi
It could be anything so if it is cheap, buy it and examine it properly. It is not likely to be a useable AF type of inductor but possibly a RF tuned filter for a transmitter or just about anything given the lack of details.
You can always paint it in 'candy stripes' and nail it to the wall as an 'objet d' art'.
Matt S

[robot gigante]

True. Actually since the box is so well built it would be worth it even to gut it and use it to house something else. Sorry about the lack of details, I hadn't a clue whether a box with "variable inductor" on it was a common, or a very random apparently, thing. I'll just go back and get it, and if there is anything interesting to it I'll post.

[The Real MC]

Variacs and variable inductors are two very different things!

A variac is essentially a wirewound resistor configured as a potentiometer. The wirewound format can handle higher power than a simple pot. It has some parasitic inductance (in small negligible amounts) but is not a pure inductor.

Unlike a variac, an inductor has an iron core whose wire gauge and wrapping pattern around the core defines the inductance.

A variable inductor was often the key tuning element in organs made from the 1940s to 1980s. But they have a narrow variability range and may not be sufficient for variable tuned filters. Plus they can break if adjusted past their physical stop positions - the movable element is an iron slab with a threaded hole and is thus vulnerable to splitting or stripping the threads.

If you want a variable tuned filter using inductors, then design it so the resistor is the variable element - the good old pot.