Ebow Expose Part II - Ebow Anatomy Inside

[Paul Marossy]

Because the slugs/polepieces have to be magnetized, that means they can be magnetized to varying strengths/gauss-levels.  I would imagine that anything which is intended to use in close proximity to strings, with the express purpose of keeping those strings moving, would be designed to have very modest magnetic "tug".  the use of Alnico is really more for the long term retention of magnetic qualities, I imagine, as well as machineability (prior to magnetization).

Good points, Mark. 

[calculating_infinity]

Thanks for taking the time and sharing with us Paul!  I remember seeing something similar elsewhere dunno if it was here or somewhere else.  Anways, keep up the good work.

[Paul Marossy]

No problem. I thought others here might be as curious as me about it. 

[psw]

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

[Paul Marossy]

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

Yep, they are just steel slugs similar to pickup pole pieces, with magnets on the bottom. But the rest of the surround appears to be a ferrite material.

Hey Pete, you should also check out the tune called "Sexton Demo 1" on my MySpace Music page, I have a cool sounding ebow part on there. Actually, it's a double ebow part...

www.myspace.com/j201jams

[Jaicen_solo]

Just a thought, but Alnico may be used because it will saturate much sooner than other steel alloys (it has a high magnetic reactance). Perhaps it helps to constrain the gauss strength of the coil when used on the lower strings?
This is something i've been wanting to try for some time. Although i'm more attracted to sustainer pickups,  having seen inside one of these things, I think an Ebow is certainly DIY-able, and I have the wire to do it too !

[Paul Marossy]

The patent documents say that the cores are Alnico-5. In the case of the ebow, the steel cores are not magnetized, so I don't know what to make of all that... 

[fafer88]

Hi,

I've just finished redraw schematic from pics. Could somebody check my schematic and pcb especially values of components and correctness of schematic? Maybe someone knows value of resistor in feedback? Instead of coils I want to use tiny computer speakers, just like this:
http://www.tme.eu/en/details/ld-sp-u15.5_8a/speakers/loudity/# -> instead output coil
http://www.tme.eu/en/details/ld-bzen-1205/electromagnetic-sounders-wo-generator/loudity/# -> instead output coil
Is this going to work?




greetings

fafer88

[Gurner]

I can't help you on the value of the feedback resistor, but normally feeding back an audio IC output to its +ve input = oscillation.

[PRR]

> check my schematic

I have NO idea what resistor "?" is for. Or why you'd use a speaker output.

Why not use the good schematic?

http://logosfoundation.org/elektron/ebow_amp.gif

[deadastronaut]

^ yep i used that schematic and  it worked....

i made a really crude...and i mean crude ebow, way off spec on the hand bodged coils too, but it worked..

http://www.youtube.com/watch?v=CO0dsElQ8Mk&list=UUGP0eO8ADt0H9FY5UcHTf8A&index=8

i wound 2 coils and just put magnets on the back of them...same polarity...

and had harmonic mode too by flipping the coils magnets....(can be done with a dpdt)...


edit:  found my old diagram, ...have fun, i did..



if i tried this again, i'd go probably go for coils just wound round the magnets (no poles) and would probably be a stronger sustain,

but will likely want to stick to the strings though....on the real ebow the string guides prevent that.........hmmmm makes me want to make one again now..

[Paul Marossy]

^ yep i used that schematic and  it worked....

i made a really crude...and i mean crude ebow, way off spec on the hand bodged coils too, but it worked..

http://www.youtube.com/watch?v=CO0dsElQ8Mk&list=UUGP0eO8ADt0H9FY5UcHTf8A&index=8

i wound 2 coils and just put magnets on the back of them...same polarity...

and had harmonic mode too by flipping the coils magnets....(can be done with a dpdt)...


edit:  found my old diagram, ...have fun, i did..



if i tried this again, i'd go probably go for coils just wound round the magnets (no poles) and would probably be a stronger sustain,

but will likely want to stick to the strings though....on the real ebow the string guides prevent that.........hmmmm makes me want to make one again now..

You are the man! 

[deadastronaut]

ha ha cheers paul....i had to try it..

[fafer88]

I drew my schematic using this PCB as exemplar:
http://www.diyguitarist.com/Images/EbowPCB.jpg
and guts posted in the beginning of this subject.
Schematic posted by PRR doesn't fit to this PCB.
I calculated feedback resistor, 62Ohm should be just fine,
I  ran simulation in Multisim and its looks good
In nearest future I want to build e-bow from my schematic,
the only thing I risk is a waste of time and a few $.
I will let you know what is the result.

[Paul Marossy]

To me, the hardest part of a DIY ebow is the package it's in. You can build the circuit, but the thing that contains the circiuit is a whole other affair...

[newfish]

Thank you *so* much for this.

I love my Ebow, but would not remotely consider taking it apart for curiosity.

In terms of the 'package', I think this will become easier once 3D Printers become more affordable...

Thanks once again!

[Paul Marossy]

Thank you *so* much for this.

I love my Ebow, but would not remotely consider taking it apart for curiosity.

In terms of the 'package', I think this will become easier once 3D Printers become more affordable...

Thanks once again!

Me neither. Someone sent me one that was already dissected. Good point about the 3D printer.

[deadastronaut]

I will let you know what is the result.

please do, i'm interested to see how you get on.  good luck


what is the feedback resistor doing then?....just curious.