It's really a pity that I lost all of my design files. I could probably design it over again from scratch, but that probably wouldn't help you a lot.
But here are a few tips:
The basic XR2206 circuit is very hard to find these days, but here it is--
http://users.ece.gatech.edu/~lanterma/sdiy/datasheets/vco/radioshack_2206spec.pdf
The sine circuit is found at fig. 8 and most of the values aren't critical. The main frequency cap should be 1 UF, while the large cap across the grounded resistor needs to be 22 uF. There's a pot in the diagram to determine amplitude, but I *think* I used a
15K resistor for that. The only pot used is the one that controls the frequency from 1 Hz to 100 Hz or thereabouts.
There's a resistor that controls the shape of the sine wave across pins 13 & 14: I think I used 150 ohms, but that's to personal taste and isn't critical either.
The 4046 VCO circuit is even easier. Unfortunately, I don't remember the vaules I used for it. A resistor and a cap at pin 9 (the other end to ground) in parallel determine how slow or fast the main 15 kHz tone shifts. If you use something like 1M/10 uf, it creates almost a slow siren-like sound; well, it would if you could hear 15 kHz, heh heh. Uh, anyway this is part preference, part practicality: at faster cycling speeds, the faster screws can turn so this has to be ballanced out through experiementation. I can't remember the values I picked.
The CD4046--
http://focus.ti.com/lit/ds/schs043b/schs043b.pdf
-- does need a 0.001 uF cap at pins 6 & 7 to get 15 kHz but this is an easy frequency as the VCO can work as high as 1 MHz. Sound that high can't even travel through air more than a few inches before-- well, let's just say it can't travel through air very far. But at 15 kHz, that's not a problem. I think there's a resistor from pin 11 to ground to control the base frequency, ut it has been a long while since I made this circuit.
Lastly, output put the 2206 at pin 3 goes via a resistor to pin 9 of the 4046 so the 15 kHz square wave is modulated by the 1 to 100 Hz sine wave. The output of the 4046 from pins 2 &3 go via 2.2k resistors into a pair of power transistors, simple push-pull kind of arrangement (I think that's what I did), into whatever miniature audio transformer you can get-- especially if it has a good turns ratio. And the screws go round and round... :-)
I suppose if you are just learning electronics-- or don't know any at all-- this is moderately difficult. The main matter like I said before, is wiring it all together so the circuit is tight and fits inside an aluminum tube, not a square box which would be normal for such a circuit.
But it's murder for me to try and rebuild the circuit from memory. This is the reason for always keeping backup files, sigh...
'Doc