AirHarp Shield

[lyratron]

Hola!

(Sorry for the double-post! I didn't see the "Kitbiz" category for some reason, so I originally posted in "Arduino Shields". Actually, I'm not sure which category this one belongs in).

I've spent the last four years of my life learning electronics for the express purpose of developing a practical musical instrument of extreme portability. You can judge for yourself, but I feel that I've finally achieved what I set out to do.

http://www.airharp.com

The AirHarp is a kind of digital autoharp that allows you to strum chords in the air on a beam of ultrasound. The pocket-size instrument is held in one hand, leaving the other hand empty for strumming. 4 pushbuttons select up to 15 chords (no button press = no sound), and a 5th allows transposition into any key. Naturally the chords you have direct access to are the so-called "diatonic chords" and their parallel counterparts (i.e., the chords you will need to play 99% of all Western music). So the AirHarp is pretty versatile in terms of the repertoire it can handle. To give you an idea of just how versatile, one of my standard demo pieces is a baroque aria ("Lascia ch'io pianga" from Handel's "Rinaldo"). I strongly feel that the AirHarp would be a great first instrument for an aspiring musician, in addition to being a fun and rewarding electronics project for kit builders.



The AirHarp Shield is an Arduino shield that transforms your Arduino Uno into a class-compliant* [with ATmega8u2 hack] USB MIDI controller instrument! Optionally, a synthesizer board (such as Modern Device's "Fluxamasynth Shield") can be sandwiched between the AirHarp Shield and the Arduino, converting the Arduino's MIDI output into audio as a standalone instrument. I've built several of these, and they work very well.

The board is in its 2nd generation, and I am now satisfied that it is ready to market. Pictures, source code and Eagle files are all available on the web site for your consideration. This project is 100% open source. I just want to get these things out into the world, because I think it would be fun to see what people do with them. Any questions, comments, suggestions or proposals are most welcome!

Yours in tinkering,
~ Peter

Lyratron ~ Engineering Elegance
http://www.lyratron.com

[adafruit]

The AirHarp Shield is an Arduino shield that transforms your Arduino Uno into a class-compliant* [with ATmega8u2 hack] USB MIDI controller instrument! Optionally, a synthesizer board (such as Modern Device's "Fluxamasynth Shield") can be sandwiched between the AirHarp Shield and the Arduino, converting the Arduino's MIDI output into audio as a standalone instrument. I've built several of these, and they work very well.

The board is in its 2nd generation, and I am now satisfied that it is ready to market. Pictures, source code and Eagle files are all available on the web site for your consideration. This project is 100% open source. I just want to get these things out into the world, because I think it would be fun to see what people do with them. Any questions, comments, suggestions or proposals are most welcome!

thank you for posting this up!

over email you said you were considering making kits, etc.

did you want to talk about that?

cheers,
adafruit

[lyratron]

Indeed! Well the bill of materials is as follows:

* 1 Arduino Uno ($30 retail)
* 1 Maxbotix LV-EZ1 ultrasonic rangefinder ($25 retail)
* 1 AirHarp Shield PCB (~$15 from BatchPCB)
* 5 Pushbuttons, 12mm ($.40 /ea. in quantity 100)
* 34 Break away header pins ($2.50 for a stick of 40)
* 1 LED, 50,000 millicandela blue + 220 ohm resistor (<$1)
==================================================
TOTAL COST: $75.50

So you see the main impediment from my perspective. Also I've been using a hack pioneered by morecat lab:

http://web.mac.com/kuwatay/morecat_lab./MocoLUFA.html

in order to make the Arduino show up as a class compliant USB MIDI controller on the computer, so I would want to share revenue with them if I were in fact selling hacked Arduinos that incorporate their ATmega8u2 firmware. If we don't include a hacked Arduino in the kit, I would be a little concerned that the customer might have difficulty executing the hack without assistance.

Then there's the matter of a case - I've used various generic project enclosures hogged out with my pocket knife, but I feel that a custom case may be in order both for aesthetic and ergonomic reasons. I recently obtained a Zenbot CNC milling machine for the purpose of carving wooden or polymer cases (as well as PCB's), but it may take some time for my feeble brain to grasp the intricacies of automated machining. Of course a case is not required as it works fine without one, but it might be good just to avoid possible short-circuits and stuff.

I welcome your insight on this! I would just love to get this project out into the world however I can.

Yours Truly,
~ Peter

[Len17]

Here are some comments from a customer perspective.

TOTAL COST: $75.50

So you see the main impediment from my perspective.

Yeah, the price is high for a shield kit, but it's cheaper than an Autoharp.You demonstrate that it's a real instrument, that's helpful.

If we don't include a hacked Arduino in the kit, I would be a little concerned that the customer might have difficulty executing the hack without assistance.

You should sell the kit both with and without the Arduino, so people who are handy with an ISP programmer can use their own. It would also make it obvious that much of the price is for the Arduino not just the kit parts.

Then there's the matter of a case - I've used various generic project enclosures hogged out with my pocket knife, but I feel that a custom case may be in order both for aesthetic and ergonomic reasons.

A custom case would be great, even if you can't offer it right away.

It looks like a very cool kit. Good luck!

[lyratron]

Thanks, Len! Everything you said makes perfect sense.

~ Peter

[adafruit]

you can likely test the waters a toe dip at a time

1) sell the PCBs and have a detailed tutorial for making the kit / modding the arduino
1a) you can put this on make: project, instructables, etc. we'd write about it for sure and so would MAKE!
2) if that works out, sell kits without the modded arduino
3) sell the full packages as well as selling the kits to resellers

this way you're responding to demand and never really unsure what people may want. the most important thing we think is documentation and tutorials, besides it being open source

for pricing you can check out some resources we've posted before.

chris did a good job summing up some of our talks:
http://blog.ponoko.com/2010/11/16/ten-r ... 94-rule-1/

a 40% margin is what is pretty common in the maker world.

slide 14:
http://www.slideshare.net/adafruit/kit-biz

if it really takes off and you need funding many people seem to like kickstarter as an option too.

cheers,
adafruit

[lyratron]

Adafruit,

Thanks for sharing your wisdom! I made a vid on how to assemble the original AirHarp Shield:

How to build an AirHarp Shield
http://www.youtube.com/watch?v=3UDGuQNFRL0

but I will probably do it again with the new version of the board, as well as a quick rundown on the Uno hack now that I've figured that out.

Your encouraging words are invaluable to me. Thanks for taking the time to help out the little guy! That's totally awesome. I look forward to tonight's episode of "Ask an Engineer".

Cheers!
~ Peter

[adafruit]

Your encouraging words are invaluable to me. Thanks for taking the time to help out the little guy! That's totally awesome. I look forward to tonight's episode of "Ask an Engineer".

thanks for the kind words!

feel free to show off the air harp at 930pm, in our show and tell too!

cheers,
adafruit

[lyratron]

Seriously?! Wow, what an honor!! *butterflies*

I've got a bit of a head cold so I might sound like a dying bullfrog, but I'd be a fool to pass up such a gracious invitation.

See you in a few hours!

~P

[lyratron]

Hey Guys,

I just wanted to say THANK YOU for having me on your awesome show last night!! Man, that was a real kick. I'm pumped up like never before and ready to do some damage!

I also really appreciate your words of wisdom, which I've taken to heart. Your philosophy about "adding value" to the world is a refreshing one, and I hope it continues to bring you karmic rewards as I suspect it will.

Gratefully Yours,
~ Peter

[mikeselectricstuff]

To reduce cost and avoid messing about hacking an Arduino, why not just stick an AVR on the board and make it a standalone?
Bare PCB cost should be $5 or less in moderate quantities

[lyratron]

Mike,

Your suggestion sounds good and I've actually prototyped such a device with a naked ATmega328 chip. The downside is that it loses the ability to do USB MIDI (though regular, old school MIDI is easy). I thought about trying the Teensy, since I understand this can be used to do direct USB handshaking as well as the other functions, but it would require some major shoehorning of the firmware. It could be worth the time investment, I suppose...

Regular MIDI is awesome, but most people use their computers for synthesis nowadays and I figure that while everyone has a computer, not everyone has a hardware synthesizer. So they would need a MIDI-to-USB converter cable (~$30), which is more than what we would save by ditching the Arduino.

With a more powerful chip, we could do analog modeling synthesis. Actually we could do this with the 328, but we'd need a dedicated DAC 'cause the onboard DAC's are a bit too slow (9 kHz refresh, I think?) Nonetheless I think a lot of people would still want the ability to do USB MIDI out.

The ultrasound is still a pricey module, and though I've developed my own (very ghetto!) ultrasonic sonar system around a naked Maxbotix-UT transducer, it's fairly glitchy and simply doesn't compare with their prefab module. The Sharp IR sensors are cool, but I doubt they would work outdoors or in an area with lots of ambient IR, so really ultrasound is the most awesome solution I've found for proximity detection.

I'm curious - where can boards be gotten for so cheap? I've been using BatchPCB and they charge $2.50 sq./inch (about $15 for a single AirHarp Shield) regardless of order size.

Cheers!
~ Peter

[lyratron]

Oh, and while I may talk a good game, have no illusions about the fact that I'm a n00b! Hence the reluctance to jump into things like surface mount and "heavy" coding.

[mikeselectricstuff]

For cheap production-quantity boards I use PCBcart - their tooling & shipping costs make small qtys nonviable but once quantites get into production numbers, prices get a lot cheaper. They also offer all sorts of funky silk & resist colours etc.
For outdoor use I'd have thought wind could be a problem with ultrasonic, whearas for IR, all you need to do is shield it from sunlight - the Sharp sensors have a very narrow field of view so this would probably be easier than wind shielding.

[lyratron]

Thanks, Mike! I'll check it out. I've used the airharp outdoors a bit, but not extensively. I haven't noticed a difference in performance, but then I've yet to bust out with it on the top of Mount Vesuvias.

I have a couple Sharp sensors but I've yet to get around to playing with them. I'll do that and see if I notice a difference. They're $8-10 cheaper than the ultrasound (depending on quantity), but there's no way I'm switching to them unless they're as good or better under all conditions.

Thanks for taking the time to share your wisdom!

~ Peter