DIY eBow

[ozbird]

DIY coils (magnets? cores?) would be a pain.  :-/

A possible alternative:
https://www.youtube.com/watch?v=fJXoSTrLBFQ

[Taylor]

It took me forever to remember the name of this thing- Gizmotron:

http://www.suppertime.co.uk/blint/gizmo.shtml

A mu-tron related product. Schematic online somewhere who knows?!?

- Strategy

And, 6 years later, somebody has bought the rights to the Gizmotron and will be producing a new version of it:

http://www.gizmotron.com/

Electronically there's not much to it, just some motors. The voodoo is in the toothed wheels that grind against the string. Actually has more in common with the vibrator motor thing than the ebow.

[deadastronaut]

^ sweet... love the chord swells, very nice..

[FuzzFanatic71]

I've got some great sounds using a vibrating sex toy as an ebow type device. When I went into the shop to buy said device, I told the person behind the counter what I was planning on using it for. They just smiled but I could tell they were thinking, SURE YOU'RE GOING TO BE USING IT FOR THAT

[Granny Gremlin]

Actually, no. I have a Sustainiac in my bass, and while it's very fun, it only will sustain one or 2 notes simultaneously. (I know you're wondering why a bass player wants to sustain 4 notes at a time, but...I just do)

Doing something like the Moog requires a separate pickup, feedback amp, and driver for each string to allow for full autonomy. Also, having each string separate lets you do different processing for each note. Lower notes may need some compression and lowpass filtering to sustain well, whereas high strings need more gain, etc.

Replying to a very old post, I know, but just wanted point a couple existing things out that might be helpful or interesting.

I don't know what Moog device is being referred to here, but there was a brief period where Norlin owned both Moog and Gibson and the RD Artist happenned. It includes active electronics by Moog (bass and treble boost/cut tone controls, bright mode and FX mode which gives expansion on the bridge pickup and compression on the neck pickup) in an instrument with a modernised (reserse style) Thunderbird/Firebird body, but all maple and set vs neck thru.  I have the bass version.





So yeah I have a thing for Gibsons, because, in trying to keep up with Fender, they took a lot of weird risks and tried a lot of innovative stuff.... another case in point:



This is the pickup from the Gibson EB4L bass.  It looked like an EB0 / 3 (SG shape) but after sales of those declined they replaced the Sidewinder (aka the Mudbucker, another crazy beast I love, despite it's limited practicality) with this thing.  Those are separate coils for each string, in a humbucking config similar to a P pup (low 2 strings in series, in parallel with the other 2 which are reverse wound reverse polarity).

Later other makers such as Wal copied the idea and took it further with 2 coils per string in a more typical humbucking config:

[Taylor]

Cool stuff. The Moog thing we were talking about back then was the Moog Guitar, designed by/with Paul Vo.

http://www.moogmusic.com/products/moog-guitars/paul-vo-collectors-edition

Those instruments seem not to be made anymore. Paul Vo has since shown some products under his own name which are relevant to this thread, but I can't figure out if these are actually available anywhere.

http://www.paulvo.com/products/

As far as I can tell, the only thing related to any of this which is actually for sale at the moment are framed prints of the PCB art...

http://www.imagekind.com/art/Vo-Circuit-art_art?IMID=d6af1ed1-ead6-4d4a-a379-9611323e8385

I used to be obsessed with Wal basses as a teenager (mainly because of Justin Chancellor from Tool using them - I was a total fanboy at that time). The pickups and electronics are certainly one of the more interesting aspects. Is your picture of a real Wal pickup or something DIY?

[Granny Gremlin]

Apparently a real Wal.  I was never into them too much so I don't know much about them other than they did the individual coil per string thing like Gibson tried with the EB4L.

Folks were talking about needing a pickup per string so I thought it might be helpful to see the prior art as it were.

[dbwbr]

hi there-
sorry responding to this long-dead thread, but it has most of the information i was looking for.
the only problem is: i'm really confused about what to use with regards to coils/transformers/etc..
does anyone have any specific suggestions for what to order from ebay that will work in the schematic?
or could someone talk a little bit more about how to repurpose a transformer?
i understand the 386 amplifier and the feedback loop - i don't understand the coils.

thanks!

[deadastronaut]

hi, in the original video going around the guy used the coils from buzzers / same as pc motherboard tiny speakers.

so you could try those.


for the fundamental and harmonic mode you will need a dpdt switch

which reverses the output coil....fiddly to do, but will work.

the main thing is building something handheld with string alignment....battery etc,

which im sure all the 3d printing dudes would conquer easily. 

[iainpunk]

hi there-
sorry responding to this long-dead thread, but it has most of the information i was looking for.
the only problem is: i'm really confused about what to use with regards to coils/transformers/etc..
does anyone have any specific suggestions for what to order from ebay that will work in the schematic?
or could someone talk a little bit more about how to repurpose a transformer?
i understand the 386 amplifier and the feedback loop - i don't understand the coils.

thanks!

well, most transformers have a few coils and a 2 part core, the I and E shaped parts.
you remove the I shaped part leaving you with the E shaped part and the coils.
you use the lowest voltage coil on your transformer.

another good salvage coil to use for the output would be a relay coil, if you have some old relay's laying around.

if you plan on buying parts, you might want to get an inductor with the highest inductance in the smallest form factor, while having at least one side open, so the magnetic field goes through the string, instead of being ''shorted'' by the core

cheers

[dbwbr]

thanks for the advice - i think this will get me going on the right track. i was hoping to ask a couple of follow-ups, though, if that's alright.
you talk about splitting a transformer to use as one of the coils.. but doesn't this circuit generally involve two coils with different impedances? is there a way to find the particular ranges suggested? does it matter? and they generally require some sort of magnet, correct?
i'm not too worried about the enclosure - this is more a matter of wanting to experiment with electromagnets.

[iainpunk]

the pick-up coil needs to have a magnet indeed, just like a  guitar pickup, the power coil doesn't need a magnet.

the splitting of the transformer is only the steel core that is split, not its coils, leave those intact. you just use the winding with the highest DC reading, with a maximum of about 100 ohm, since its probably the highest inductance as well. you use the ''E'' shaped rest of the core to ''focus'' the magnetic field onto the strings, 3 paths for the magnetic field is more attractive than a single path and having to go through air!

the impedances of the power coil does indeed have an impact on the effectiveness, higher inductance is better. To a lesser extent a lower DC resistance is also better, but generally, coils with more turns of thinner wire have more inductance and more resistance, so as long as the DC resistance is lower than about 100 Ohm, you'd be alright with getting the highest inductance coils you can find.
try and get some ''straight'' inductors since a lot of ''closed magnetic loop'' inductors are impossible really hard to modify for this use

cheers, Iain

[Taylor]

Around 10 years ago when this thread was originally going, I bought a bunch of the piezo buzzers from Mouser and built up a copy of the circuit from the first page on perf board, and experimented with coils. I didn't take notes but I was actually able to get it working like an ebow.

I had to cut away the plastic surround, but at the time it seemed easier than dismantling a transformer. Here are the part numbers I ordered, not sure which one(s) ended up working best.

https://www.mouser.com/ProductDetail/665-AT-1620-TWTR
https://www.mouser.com/ProductDetail/665-AT-1224TWTR
https://www.mouser.com/ProductDetail/810-SD160701
https://www.mouser.com/ProductDetail/810-SD1614T5-B1
https://www.mouser.com/ProductDetail/810-SD1614TT-B1
https://www.mouser.com/ProductDetail/810-SD1209T5-A1
https://www.mouser.com/ProductDetail/810-SD1209T3-A1

I've been wanting to get a 3d printer for a while, so if I get one this year, maybe I'll try to get back to this stuff.

[iainpunk]

I've been wanting to get a 3d printer for a while, so if I get one this year, maybe I'll try to get back to this stuff.

i want one too, but my parents don't trust me with such dangerous weapons.

i recommend you to build a ''sustainiac'' pickup, its easier to build in a guitar, at the cost of a neck pickup tho. just mute all strings you don't want to have playing.

i wonder if you could get it to work without the feedback loop, but a sawtooth LFO driving the coil, to activate the strings a few times per second, instead of resonating the string. might try that next week!

cheers

[Taylor]

I actually have a Sustainiac system in one of my basses. It's very cool, but one thing that handheld versions have over it is that you can move an ebow around along and above the string, closer and farther from the pickups, to get all kinds of expressive effects. I've also got an ebow already, but my plan with the 3d printer was to make something that fits bass strings better, and potentially offer this as a DIY project on the MusicPCB site. A circuit and coils ain't much use without some kind of case.

I'm not sure driving the string with a sub-audio signal (i.e., no feedback) would work very well. But you could insert a VCA circuit in the feedback loop if you want to use an LFO to modulate the level of drive.

[Marcos - Munky]

On the diy ebow using buzzers:
https://www.youtube.com/watch?v=UkQhRFS6sRM
https://www.youtube.com/watch?v=1iccGqmEC-M

[R.G.]

Thanks for the info... how much different is the driver coil from the pickup coil?

This is a long shot, but I have this inductor that I pulled from a TV I dissected. It looks like a large-ish electrolytic cap. Could something like this be used as a driver coil?

I am actually interested in this for a totally different type of instrument... a stringed/keyed instrument like a harpsichord, but with a method of producing sustained notes. I had thought of mechanical methods of doing this, but doing it electromagnetically may actually be a better way.

Good idea! I was after something similar a few years back. I liked the idea of a slow fade-in note, and concocted a Frankenstein setup based on an mbira/kalimba. I went to Home Depot and got a garden rake with steel tines and one of the bonding strips for breaker boxes from the electrical department. This was a steel bar with about a dozen holes for the thick copper wires, and setscrews at each hole. The idea was to cut off the tines, stick one in each hole, and use the set-screw to both hold it in and allow note-frequency adjustment, ala the mbira. The bowing circuit would sit one each under each vibrating prong.Each prong got a pickup coil. I got one tine built and working before life interfered with the rest of the test.

I'm thinking from your description that you intend to key the bowing circuit. That's what I was doing. A mechanically resonance like a guitar string  starts vibrating when outside force sends in energy to excite the resonance. This can be marching soldiers on a bridge, a clanger in a bell or an e-bow on a guitar string. Whacking a resonance, as with a bell, or guitar string starts it off with big vibrations that decay away as it loses energy. Putting energy back into it with some kind of feedback circuit like the e-bow can feed back in enough to lengthen the vibration, even out to as long as the feedback exists. Since there is always noise, just doing feedback will eventually start up a vibration in the resonance, and more feedback gain starts it faster. So adjusting the amount of feedback can actually adjust the fade-in of a keyed note. I think... 

Using a permanent magnet in the drive coil starts these things faster. The magnet pulls on the string/prong, and feedback adds to/subtracts from the magnetic field as a kind of tiny "whack" to kick things off.

But I'm rambling. Good on you for digging into this. Let us know how it works out.

On the theoretical side, the e-bow amplifies picked-up

[deadastronaut]

i remember a few years back member 'artifus' on the sustainer thread

tried magnets, with inductors....i tried it too and it worked.

just putting it out there. 

[dbwbr]

hi again
i ordered transducers from Mouser and built a circuit based on the design in this youtube video (https://www.youtube.com/watch?v=1iccGqmEC-M) but it's still not working as expected. has anyone successfully build one of these here? would you consider reaching out to me via DM?