DIY Airpiano

[Old Plucker]

Just noticed this thread.
So, here's one I made earlier, from 2007 I think.

https://unstablesound.net/skullamin.html

Arduino, ir sensors, leds & Max/MSP for the interaction & sonics

[Arpangel]

I'm pretty sure there'll be a DIY shop near you that will cut sheet materials and timber to size, I was going to suggest B&Q.

Right! Now, that's a great idea. (As for joiners workshops...never heard of them. I'll look them up. I have almost an allergy to this stuff. Arpangel, don't worry, it'll be fine...)

Don’t worry, I’m not worrying!

[BJG145]

The Arduino Mega clone arrived and works a treat. Still waiting on the extra sensors. I think I'll forget the MIDI shield and just go with MIDI over USB with a couple of buttons for presets, and an expression pedal input, like the original.



I've found a local craftsman who's going to build the case. I just ordered a couple of samples of 3mm and 5mm Red Tint 4401 Perspex to test with the sensors and make sure they still work OK.

https://www.perspexsheet.uk/red-tint-4401-perspex/

Do I need to worry about ventilation, I wonder...? I've specified a 2.5cm space to fit the electronics. Slots underneath maybe, or drill holes or something...? Not sure what the additional power requirements might be either, especially if I start adding LEDs. (40 of those square dots in the original to display height; bit of a gimmick, but I might work on it.)

[Martin Walker]

Do I need to worry about ventilation, I wonder...? I've specified a 2.5cm space to fit the electronics. Slots underneath maybe, or drill holes or something...? Not sure what the additional power requirements might be either, especially if I start adding LEDs. (40 of those square dots in the original to display height; bit of a gimmick, but I might work on it.)

It all depends on how much current is being drawn by the electronics, which in turn will determine any temperature rises. Difficult to make a guesstimate methinks.

I should construct the circuit board and run it on a test rig to see how warm it gets, and that should give you a better idea.

As for the LEDs, most red ones will provide a suitable level of illumination with 5mA current, but that still means 200mA in total.

Martin

[BJG145]

Thanks Martin. I just did a bit of Googling on LEDs and Arduino, and it all seems to be about Neopixels now, so I just ordered an eight-way strip to test.



They seem to come in various shapes and sizes and you can daisy-chain them to the Arduino.





All the nice colours will be a bit wasted behind 5mm of red-tinted Perspex, but that seems to be just how they come, and as with the Arduino there are plenty of cheap compatibles.

I don't know the practicalities of handling current and power with Arduino. So far I've only powered individual sensors and LEDs from the board. But with eight of those strips, and eight of the Sharp sensors, I'm thinking I might need to build a separate power circuit...? In the pic of the original Airpiano above it looks like there's an input for a PSU next to the USB socket and this spec sheet mentions 9V power.

[BJG145]

Extra sensors have turned up, along with the perspex samples. It seems to come in standard 3mm or 5mm sizes. Having tried both I think I'll go for the 5mm; it's nice and chunky and isn't going to bend any, so I've passed that request on to the joiner.

Both thicknesses seem to work similarly with the sensors, which is that as long as it's really close it doesn't seem to affect them much, but if you move it just a few mm away from the surface the readings go off. Reflections or something I guess, so I'll just have to make sure they're fitted closely against the lid.

After starting to look at the MIDI over USB library for the Mega it turns out that it doesn't support it natively, but it sounds like there's a workaround using this library so I'll give that a go. Or I could stick to using the MIDI shield, and it would be quite nice to have proper MIDI in/out, though the case won't be deep enough to support the stacked boards so I'd have to wire them together side by side. Should be simple enough, though I'm surprised it's not easier...I'd have thought there would be common adaptors or cables or something for this but I haven't found any yet.

The Neopixels strip has also turned up; these look fun, and fairly straightforward. There are connectors either end for ground and power. One end has "data in" and the other has "data out" and I think you can just wire them up in series then address individual LEDs in the chain using a standard Arduino library. Going to need some solder to connect it up though; it's been a while, and after spending half an hour rummaging around in sheds and drawers I gave up and added it to the eBay list. Besides, I like getting these little envelopes turn up every day or two with components.

I've found that the Arduino maxes out at 200mA so it won't be able to power everything. The IR sensors take up to 30mA each, and individual Neopixels can apparently guzzle up to 60mA each on full brightness, though you could get away with a lot less. I'm thinking, maybe 20mA per pixel, 160mA per strip, 1280mA for eight; plus 240mA for the eight sensors gives 1520...so a 5V DC supply rated at 2A ought to do it. I'll do some experimenting with a breadboard.

[Folderol]

ULN2803 is your friend. 8x darling transistor that can directly connect to the arduino and has a output current of 500mA per channel, but a total power dissipation of 2.25W. That's not as bad as it looks as even with all devices on at the same time you can draw over 100mA each (they'll only drop a volt or so).
Cheap as err... chips
Here

P.S The outputs can also stand 50V when off.

[BJG145]

Thanks...I was wondering if I could just power the Sharp IRs and Neopixels in a simple direct way from some other circuit, hit them with 5V, and just use the Arduino to receive the analogue input from the IRs or send data to the Neopixels without needing transistors...? Not sure why the Arduino needs to be able to control the amount of voltage to these devices, if that's what the transistor is for...? (Neopixel brightness is apparently controlled like this. Each LED in a set has its own chip.)

[Folderol]

Ah. I think I misunderstood how you were using these. I thought you were using the Arduino outputs to switch the sensors, but it seems you using its USB link as a power source. In which case, a trick I've seen used a number of times is to run a second USB line from the computer used only to provide 5V power.

[BJG145]

First test with the Neopixels strip...

https://youtu.be/s5vbRdKg_os

I'll go with eight of these as height indicators. £3 a pop, easy to program, and as bright as you like - I'm a convert.

[BJG145]

Just had an email to say that the case is finished and ready for collection. Look forward to checking this out...

[Hugh Robjohns]

Really looking forward to seeing this!

[Martin Walker]

So am I - your collection of controllers must be quite awe-inspiring by now BJG145!

Martin

[resistorman]

It would be fun to have something like this that output CV to control my Arbhar!

[BJG145]

A while back I sent the IR sensors to a MIDI instrument designer of my acquaintance to tinker with, and he just sent me a link to a video with the latest progress. It's looking quite promising.





Here's a pic of the case I had made up by a local joiner, though it's not the most flattering angle.



Ultimately I'll arrange a proper photoshoot, hire Durham Cathedral or something.



That's Jo Hamilton, of course. There seem to be very few videos of anyone playing one of these, but here's a bit of There It Is.



https://www.youtube.com/watch?v=gG2hFVn ... JoHamilton

[Folderol]

Nice to see this progressing

[Martin Walker]

Indeed - controllers come and go, but the one's you're involved with tend to result in rather more expressive possibilities.

Martin

[BJG145]

My DIY MIDI partner in crime has been working on pitchbend. I think he's now ready to kick this project out the door and send it back, so I'm hoping to have it ready for action within the next few weeks.

[Drew Stephenson]

Not really relevant to the thread, but there's something about the design of that mouse that makes it look much older than it is. It's almost a throwback to the 50s or 60s when everything was designed to look like a spaceship!

[BJG145]

...ah, trackball mice. Hate 'em.

Whenever I've been called out to a desk with one of those I've always had to nip back and fetch a proper one. Trackballs are only good for one thing.



https://en.wikipedia.org/wiki/Missile_Command

there's something about the design of that mouse that makes it look much older than it is. It's almost a throwback to the 50s or 60s when everything was designed to look like a spaceship

(What do you make of Elon's rocket design? It's been described as "anthropological".)

[Drew Stephenson]

It's a bit Flash/Flesh Gordon isn't it?

[ManFromGlass]

Now there’s a combo that will provide hours of fun in space!

[BJG145]

The finished board ready to be returned and fitted inside the case...

[Martin Walker]

Looking good!

[BJG145]

The guts of my Airpiano, ready to go in the morning post...





(Crosses fingers)