Electronics question, Vari-loopstick?

[pX]

Alright, I was building my brother a Thereman(sp?), one of those things that you wave your hands around and it makes what they call "music".

Anyway, the schematic calls for a "Vari-loopstick". Never heard of it. The symbol is the same as an inductor, so I am assuming they are one in the same, perhaps a variable inductor? But it gave no rating, I thought variable inductors would have ratings of xH-yH or something....

Anyone ever heard of a Vari-loopstick?

 

[Killbat]

Never heard of such a beast, and can't find mention of it anywhere.

If all else fails, try a different design.
http://www.thereminworld.com/files/projects/glasgow/revised.gif

[edit] Lookie here:
http://home.att.net/~theremin1/144/144.htm
His schematics have much more info on them. Looks like an adjustable inductor.

 

[pX]

those look a hell of a lot better than what he gave me:
http://www.coolidge.org/tour/theremin.html

extremely simple here, he just wanted it fast basically.
I think I'll try one of the ones in that second link, however I'd still like to know what they are talking about when they say "vari-loopstick"

 

[Killbat]

The part probably looks like a cynlinder with the coil wound around the outside, and a ferite core that screws in/out. It's variable, and it's a loop of wire around a "stick". That's the best excuse I can think of.

 

[pX]

so I can buy a similar part? any idea what it would be called?

 

[DRGrim]

<< The SWTP circuit uses ferrite core "loopstick" variable inductors for frequency adjustments. In the 144 Theremin design, these variable inductors are replaced with fixed-value, J.W. Miller type 4652, phenolic core, 1 millihenry, pie-wound inductors. In lieu of the variable inductors, coarse frequency adjustments are made with variable capacitors; C2 in the volume oscillator and C22 in the pitch reference oscillator. The new combination of stable, fixed-value inductors and variable capacitors improve the oscillators' frequency stability with temperature change and eliminate the loopsticks, which are costly and hard to obtain. Note, also, that the new design eliminates the variable functions from both the volume processor and the pitch variable oscillator; the nulling adjustments are made only in the pitch reference oscillator and volume oscillator sections. >>



From Killbat's 2nd link.

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