Great thread and I'm glad the dismantled ebow fell into good hands. That Phil Keaggy video ebow demo is pretty inspiring...in many ways it would seem that the ebow is the ultimate sustainer (at least it is portable from instrument to instrument)...http://www.youtube.com/watch?v=wwq0i6jP7dQ
I have always intended to build my own (they are a little expensive down here for me! A$300!)...have shot you an email paul. I was wondering if any ergonomic improvements could be made to the design?
The circuit is ultra-simple and I already have plenty of similar ones for the sustainers I have been working on...and experience with coil making. Winding driver coils is not hard...a few hundred turns, if that of fairly thick enamel wire (0.2mm) will do the job...making the pickup coil may be a little harder...this hair like pickup wire needs to be bought in some quantity, is hard to source and really needs a machine (a drill would probably do it) to wind!
I suspect that the coils are simple steel slugs with magnets under and the steel rings (probably cut from a metal pipe...or at least could be) is there to allow some magnetic sheilding and allow the driver and pickup coils to be placed so close together. A device like this need not have a lot of power and a preamp would not be necessary if the pickup was an appropriate impedance for the amp (maybe 10k or so). People should keep there eyes peeled for suitable off the shelf coils for the pickup coils...some reed relays have interesting coils that could suit the purpose. The dutch DIY ebow site suggests a phone pickup...don't see too many of those around...hmmm Perhaps even speakers could be used as applied to intercoms for both the driver and pickup coils if suitably modified...
The real elegance in the design is in the enclosure...and that is hard to replicate. I wonder if anyone could come up with an alternative design or format that would work as well?
Anyway...interesting stuff and an invaluable reference...glad to see the pics have not been lost in the cyberspace...I'll let you guys know how any experiments I may try work out... pete