I'm not suggesting this is in any way useful to you, but I know you're a fan of phasers (I am quite fond of them myself), so I figured you'd appreciate all things phase...who knows, maybe something in the circuit will give you ideas for some future phase related endeavour.
The idea behind this circuit is that it takes CW (morse code) signals and uses phase delay to create a spatial pseudo-stereo representation of the morse code. Why would you need this? Well, the pitch of a CW signal you hear on your radio depends on what frequency you are tuned to, plus the frequency you have your beat frequency oscillator set to - for example, if I like to listen to a 600hz CW tone, I set my BFO for 600hz, and tune exactly to whatever frequency the sender is on - that results in a 600hz tone in my ears. But, there can be many adjacent CW signals near where I'm tuned, and because I'm not tuned to their frequency, but still have my BFO at 600hz, and if i have a sufficiently wide bandwidth filter set, what I hear is one CW tone at 600hz, and others at higher or lower pitches proportional to how far off frequency I am when mixed with the BFO frequency.
So what this circuit does is basically use phase to split out tones higher and lower than ~580hz, and put them in the left and right ears. The result is some CW tones "appear" right in front of you, and the rest are spread out spatially in your ears to the left and right soundstage. It's a neat idea, and I think it works because our ears in part use phase for positional information - its definitely a more nuanced approach than just using high and low pass filters and spreading the tones out that way.
http://cq-cq.eu/DJ5IL_rt001.pdf
Sound samples here, if you scroll down to the section about the "codephaser" :
http://cq-cq.eu/root.htm
I bet something like this could be done for guitar, centered on some useful guitar frequency, but I also think the effect would really only work with headphones - I'm totally guessing, but I would expect the effect would either be too subtle with two amps, or would just sound bad open air because of the two signals not being in phase. BUT..if it had some drive to it, you could swap the high and low portions of the tone left and right across the soundstage, which would be like some weird, maybe like a crazy Leslie effect? Maybe it would just sound like crap.
One other thing that struck me as odd in the circuit is that it explicitly calls for some 1% tolerance components - I haven't studied the circuit enough to understand why, although I'm guessing its because its working with a very narrow frequency band and the phasing effect needs to be dead nuts on for it to sound right in the headphones.
BTW, if you like rhythm guitar, you'd like morse code. You can get some swing going as you pound out messages, and musicians are almost invariably better at sending than not (unless your rhythm playing sucks, guilty as charged). I've worked my way up to 12 words per minute over the last couple months, which I'm fairly proud of - it's a lot of practice, I figure this is a crowd that knows what that entails
-Scott