ebow-y idea

makepeace

hi guys.

i've been wanting an ebow for a while now, but last time i checked with Andy McGibbons, they didn't have stock, and they're the agents in SA.

i was thinking about building one. i checked it out on the net and there are a few design schematics available that consist of a 9v battery, a 50ohm coil, an 8ohm coil, a pcb with an opamp and various other things passive components. then there's obviously the problem of designing/building a suitable enclosure.

here's my idea of something that might work similarly (shoot me down if i'm wrong please).

9v battery -> inverter (converting the DC voltage to AC voltage) -> AC output to coil going around a piece of metal

the AC current going through the coil will induce an alternating electromagnetic field in the piece of metal, which would then be brought near to the string(s) in order to make them vibrate..

ok after writing that all down, i've just realised (let me know if i'm right) that the alternating magnetic field will have a fixed frequency, which will only vibrate an object of the same frequency.........................

damn.

Gearhead

No problem, instead of using an oscillator (you call it inverter) you just amplify the guitar signal. That's the way ebows and sustainiacs work anyway. Then all you need is a buffer amplifier in parallel to the coil amplifier, sending the signal to your amp.
In terms of enclosure you need something ergonomic that will allow you to still use your picking hand. I have a hunch that the main advantage lies there: design something good and beat the ebow.

The real challenge is in making those amps dead quiet, otherwise you get back to oscillation amplified to squealy noises.

AlanRatcliffe

Its very simple. You just have an input coil too (basically a pickup) that picks up the signal from the string. The signal is amplified by an opamp and the output feeds a driver coil (which excites the string). If you invert the signal to the driver coil, it damps the fundamental, which pulls the harmonics out of the string (aka "harmonic mode"). The real problem is avoiding unwanted feedback.

Here's a schem of a simple one:

The Patent:
http://www.diyguitarist.com/Misc/Patent_4075921.pdf

[EDIT: Gearhead beat me to it]

makepeace

ok been mulling this over..

found a video of this guy making one:

could be done with relative ease i think ?. i have an idea for the enclosure which i won't shed any light on yet.

there is one difficulty that i can see, namely getting two coils of a reasonable size (about the size of a 10c coin) with the right resistance. the guy in the video mentions a 50 ohm for the input coil and 8 ohm for the output coil. he's using pc buzzers. i've looked at mouser's website and the 8 ohm shouldn't be a problem, i'm having trouble finding a 50 ohm, within a similar size constraint of the 8 ohm. anyone know where one can be found?

Ray

Sorry to hi-jack but is this what this e-bow thing is:

http://more.take2.co.za/moreusa-heet-sound-plus-ebow-electric-bow-for-guitar-b000n5mk8m.html

makepeace

its just that ?

didn't know you could get from take2, so thanks for that. pretty damn expensive though..