Auto Xylophone with Homemade Solenoids | Hacker News Reader

Auto Xylophone with Homemade Solenoids

rachad47.github.io

71 pointsphoenixreader38 comments

Pretty cool! FWIW, this is a glockenspiel or bells (https://en.wikipedia.org/wiki/Glockenspiel), not a xylophone (https://en.wikipedia.org/wiki/Xylophone).

Sorry to upvote a pedantic comment, but the instrument here is definitely not a wood or kelon xylophone, and is instead a glockenspiel. The solenoid striking scheme would probably need to be slightly different for a xylophone, to avoid wear on the more delicate keys. A softer, rounded tip, needing more clearance beneath, would probably be required. Marimbas and vibraphones would require even softer strikes as well. Really great project!

Very cool project! But I would dispute this:

> buying 24 Solenoids is quite expensive

They're about $1-2 apiece on Aliexpress; I doubt making your own can cost much less?

In my experience, making one solenoid is fun just to see how it works (and how simple it is, really); but making more than one is a little painful and not fun.

Personally I avoid buying direct from China whenever possible because I want parts quickly so that I can make progress on the project.

The cheapest solenoids I can see on Amazon Prime are about £5 each. 24 of those would be over £100.

Plus, the stated goal of the project is to learn a bit more about electromagnetism, so making your own solenoids is not even a bad idea.

> to learn a bit more about electromagnetism, so making your own solenoids is not even a bad idea

You can learn by making one. Making 24 is super annoying IMHO.

(Also, if you want to try, ready-made sewing machine bobbins are a good alternative to 3D-printing your own solenoid body.)

And about the rest of your comment: one approach would be to buy one solenoid from Amazon, to let you do experiments and set up the whole machine, while waiting for the rest of the goods to arrive from China.

I had most of my Aliexpress orders arrive in something like 10 days. Is it much slower in the UK?

You have to make sure you get the fast shipping else it takes a month.

That's almost 2 weeks! Amazon Prime comes the next day.

I guess I'm just not as spoiled ¯\_(ツ)_/¯

I'm used to my online purchases taking time. The closest thing we have to Amazon is Ozon, it's 1-2 days if you buy something that's already in a warehouse in your city (i.e. if you're lucky) and several more days if it's not.

why would you buy solenoids from amazon instead of an actual electronics distributor?

I pretty much always buy components from either Amazon or eBay. Is that unusual?

I just looked on Farnell and the cheapest solenoids that I could find in stock have a weird housing (and they're £6.38 each which is already more than Amazon), the cheapest sensible ones that are in stock are £12 each, which is way more expensive than Amazon, plus you have to pay VAT and postage on top, plus you have to faff around with their enterprisey order form, compared to one or two clicks on Amazon.

Yes, it's unusual for professionals, just fine for hobbiests.

Because of reliability, etc.

For the same reason you wouldn't order your ingredients for a professional Michelin starred restaurant from Amazon.

I've almost never found Amazon cheaper either. The sellers on Amazon are almost always not the original manufacturer, they're usually FOB folks who are just buying big boxes of things and then selling them individually.

You're almost always better served to swim upstream and get things from the manufacturer, or from reputable electronics distributors like digikey, Farnell, mouser, jameco,etc. A quick search at some of those and I'm finding suitable solenoids at $2-5

Sometimes, because you Just Don't Care™ about any particular manufacturer spec, and you're unwilling to pay egregious Digikey/Mouser markup times 24.

It's not that Digikey or mouser is taking those inexpensive overseas solenoids and marking them up.

The products on mouser and digikey are from reputable industrial component manufacturers. They have warranties and datasheets, support from the mfg, traceability and trustability, etc.

They're simply different products. You can't compare a quality made product from a quality supplier and manufacturer to cheap crap you buy on amazon

It's both. The product on Digikey is quantifiably better in many regards. It's also got a price premium on top of the increased price from the OEM. You have to pay Digikey enough to make it worth their while to ship 1 of something to you.

And if you value your wn time above even minimum wage it's a trade well worth taking.

Pat Metheny made an album called Orchestrion using an entire orchestra/band of real instruments played by solenoids over MIDI. Great music. (If you like Pat Metheny.)

It was an insane project. He even took it on tour.

The actual build was by Eric Singer and his team.

https://www.wired.com/2010/01/orchestrion/

Although I missed seeing the Orchestrion tour in the 2010s, Pat still takes a subset of these instruments on tour with him. Both of his two previous tours, Side Eye and Dream Box had parts of the concert that had robotic percussion and wind instruments.

Aphex twin did a similar project with “computer controlled music”

  "I used to hate electromagnetism"

Not a sentence I expected to hear today.

Without it, life as we know it is not possible.

You do know high frequency electromagnetic radiation can cause cancer in skin tissue ....

It’s like the best homemade doorbell ever!

I have a full octave of organ pipes, and I've always dreamed of making an instrument out of it. I've just never figured out how to make the electrically-actuated valves.

Which pipes are these, out of interest?

As for electronic control, it shouldn't be too hard - perhaps you already know the following, but I'll write it here in case it's useful. You'll need as many electromagnetic solenoids as you have pipes. First you need to construct a 'wind chest', which is a shallow, air-tight box that can be made of any material. A plastic storage tub should do fine. Then you punch a hole in the top of the wind chest for each pipe, and make some sort of grommet to hold the pipes in place in the holes; this would be a 'toe board' on a real pipe organ. Mount the solenoids directly under the holes, and attach something soft to squish up against the pipe and stop the airflow. You of course need to have a blower that can pressurise the wind chest.

No guarantees about how that's going to sound! :) If you wanted to construct something really high-quality, you could follow Raphi Giangiulio, who has documented every stage of his fully-mechanical tracker organ: http://www.rwgiangiulio.com/index.htm

Have you seen Look Mum No Computer’s series on making an organ midi controlled?

The artist is Grandbrothers and one of them is a jazz pianist and the other one is a roboticist. The latter sets up systems to control solenoids striking the strings and body of a grand piano while the former plays on the keys. It's a duet between human and machine.

Fun project, they could have hand winded those solenoids which a drill instead…the end result would look way better

I have to say, those are some ugly solenoids. Is it really that unusual/ocd to want them a little neater?

The Yamaha Disklavier is a player piano that uses a similar solenoid actuation technique: https://en.wikipedia.org/wiki/Disklavier

This is something I've dreamed about doing in one form or another since I was a teenager almost 30 years ago.

But the best thing about this story is the video "Without the Xylophone" - a terrifying robotic bed of nails.

Looks very interesting. I see Arduino is used here. Do you feel the latency?

You can have a look at Daisy and Bela as well :)

Daisy and Bela are great for low-latency interactive audio :)

But I think Arduino is a good choice for this.

1. The microcontroller isn't generating audio onboard, it's driving solenoids to hit something. Arduino can do that — the solenoids have travel time but Bela wouldn't solve that.

2. This is more like a sequence playback machine, there's no continuous real-time interactivity. Play/pause is the main interaction and a few ms is ok.

(If you wanted to duet with it latency-free the top of the xylophone is completely exposed so you can just play it normally.)

Artificial Intelligence is mentioned in the intro, but was it actually applied?

would it be possible to induce the vibration of the metal piece (assuming it's magnetic) without nails?

using very rapid magnetic oscillations (like a speaker??)?

I think the electronics would be different, but is it possible?

probably!

You might like the Magnetic Resonator Piano: http://instrumentslab.org/research/mrp.html

Cool device. The electronics for "continuous note shaping" would be a lot more complicated than just 'hitting' a note, which could be as simple as a single pull and release (probably not very loud without a much stronger electromagnet).

You could send a plain sine wave matching the frequency of the bar above it, but at that point you've just invented a single frequency speaker.

Very nice way of showing the build progress with the animated gifs.

Reply on news.ycombinator.com