DIY Scaled-up EBow-type Feedback Device

I’m curious if the community has some insight into the type of device used by Oscillatorial Binnage on their junk wok instruments. From what I can gather, there are two coils placed opposite one another along the rim of the wok, creating what I assume is a feedback/exciter device similar to an EBow.

They get some fantastic drones out of these things. I’ve done a bit of research into the EBow, and the circuit looks pretty simple: coil 1 > amp > coil 2 > coil 1…ad infinitum. There must also be a pick-up of some kind used.

Anyway, love to hear any ideas you all might have. I got junk I need to vibrate! Oh wait, that came out wrong…:grimacing:.


Well there’s a contact link there, that’s probably the best way to get specifics.

I liked using ebow on electic cello once or twice, but it was too weak, so I had to boost the signal a lot. So I’m also curious how to diy a custom ebow.

Yes, I’m aware I can contact them directly. There’s lots of good brains on this board though, and potentially many ways to skin the proverbial cat. I’ll be happy to pass along anything I dig up in other places.

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Heh, I saw this thread and changed the status of this thread to “Tracking” as I wanted to keep up.

I definitely dig the idea.

Looking back on the Wond webpage, I guess they’ve been designing an EMpick for some time now, with kind of a seedy looking “pre-order, but with no pictures/info/etc…” sort of way.

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Yeah, that’s supposed to be a new a improved version of the first Wond. Tho the page was inactive for a long time now.

That first one sounds mechanical. I don’t know what these guys are doing, but go to and search for Dayton transducers. If you want to oscillate things then you need some of these in your life.

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maybe related:


@timp oh, now that’s interesting. heading off to the magnet stash. thanks for this!

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I’ve built rudimentary ebow using this schematic in the past. input inductor is 8ohm, and output is 50ohm. You can get radial metal core choke that work well for this on tayda/mouser etc. Or wind your own magnet coils!

LM386 is a common low power audio amplifier



@ElectricaNada Thanks for the Dayton transducers link. Those look promising. I recall @Rodrigo mentioning these in the Piezothing feedback instrument thread.

Looks like they need to be in direct contact with the material you want to vibrate. I’m curious if they are able to work with a small gap as well. I’m envisioning something where the vibration-inducing device (whatever that ends up being) could be moved in relation to the vibrated material during a performance. Or even better, a super lo-tech autonomous kinetic sound sculpture that is able to move the vibration inducer in relation to the material.

@dianus This is a great starting point for the circuit. Thanks so much!

I think I have everything but the op amp somewhere in the basement. Off to Mouser…

Making electromagnets is quite an interesting youtube rabbit hole! It doesn’t seem difficult to build a powerful electromagnet, and (thinking aloud) if power was applied periodically (rapid DC switching on/off = LFO square wave?) towards audio rate, then would whatever metal object was near the electromagnet vibrate sympathetically at the same frequency? I wonder if there is lag, ie how fast the electromagnet powers up & acts? An eBow has some lag - exciting a string is not instantaneous… Experimentation is likely the only answer…

Consider the hurdy gurdy bow. It’s nothing more than a spinning disk of wood with some bow rosin rubbed on the edges.

Also, someone posted a youtube of his mechanical exciter for tibetan bowls on this forum within the past year or so. That’s well worth a look if you can find it.


You’re reading my mind on the hurdy gurdy. I was actually thinking about that for another project.

Yes. The rabbit holes are multiplying, as rabbits tend to do. I like the idea of modulating the electromagnet.

It has been awhile but I messed around with string exciters with Eurorack in the loop. It would be fun to try driving other objects. What worked best for me was using a permanent magnet wrapped with magnet wire when driving a string. I used an alnico rod magnet and 34AWG wire (1500 turns). The coil was driven with a DRV tile but any little amp will work.


While I do like my eBow, the “static” sound of it is one of the biggest issues I have with it. A wave shape hack for an eBow would be amazing.

Or, a multi string exciter with assignable wave shapes for each string.

I don’t think it’s made anymore, but I think Moog had a guitar that did something like that. Or it might be another company that I’m thinking of, that had this attachment for an acoustic guitar that worked on a similar principle but created “other” tones too.

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@pulplogic That’s super cool. Thanks for posting.


yeah, the moog guitar, which paul vo designed… 2008 or somethig. it was pretty fun.