This week, I have been mostly working on... » MIDI and Music

…infringing patents (probably)

Stephen Hobley — Wed, 23 Nov 2011 18:12:09 +0000

I’ve been meaning to build one of these for ages.
Can anyone guess what it is?

It’s not a Taser, or one of those shocking buzzer things – the clue is that the coils are well “potted” and have very different gauges of wire.

Answers on a postcard please, or in the comments…

UPDATE : Correctly identified as a “guitar sustainerizer” otherwise known as an Ebow.

The circuit is a simple audio amplifier based on the LM386 (or in my case the NTE823) IC.

The two coils are taken from old telephone pickups – one (input) has a small rare earth magnet on the back, the other (output) was unwound and rewound with about 300 turns of #32 wire – this coil now has a resistance of just under 8 ohms. I tried a 4 ohm output coil, but the IC got too hot so I doubled the turns.

Note – I recently found a better candidate to make the coils with – tiny PC speakers.

The input coil has a resistance of 250 ohms – this is probably too high – I read somewhere that 50 ohms is probably better – so I may remove some of the turns on the coil.

Tomorrow I’ll publish the circuit and the etch mask, along with a video of the device in action.

…and here’s the patent

UPDATE2 : Here’s the schematic, placement and etch mask – click to enlarge

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…Fritz Lang’s Theremin Stand

Stephen Hobley — Sun, 06 Nov 2011 20:13:27 +0000

(Sounds like something you’d find in Warehouse 13)

For many weeks I’ve been trying to come up with a cabinet design for the vacuüm tube Theremin I built a while ago.

I decided that the electronics were far too marvelous to hide away in the classic RCA “drinks cabinet” – and that something more radical was required. (Electronic design by Mark Keppinger – more information is available here)

…and it had to have *lots* of elliptical curves. (‘Cos nothing says CNC like ellipses)

What I wanted was something that would be open enough on the front, back and sides so that the coils and tubes would be visible. It was routed from 3/4″ MDF and then the beveled edge was created using a small table router and “tracing” bit.

I still need to figure out a way to attach the antenna – and replace the 1/2″ copper tubing with some stainless steel, or brass. The front panel will eventually house the pitch tracker and midi interface I designed.

(Yeah… it’s dusty)

The speaker is not in the ‘ideal’ place for performance – it should really be behind the player’s head. This position does allow the speaker to be placed facing forwards or backwards, and it can be removed completely and placed on another stand if required.

I’ve been experimenting with different paint finishes – and I think that black satin is probably the best. High gloss would be nice, but requires more maintenance. Unfortunately the seasonal window on spray painting is starting to close, so it might be spring next year before I can finish the project.

…and even though the Fritz Lang thing was a joke – it does remind me of this scene from Metropolis.

Update:

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Air Guitar? …meet Air Piano

Stephen Hobley — Sat, 05 Nov 2011 18:17:21 +0000

My buddy John Claeys sent me a link to this video of the AirPiano device being demonstrated by Jo Hamilton.

I’ve not been able to find out too much about the design or origins of the instrument. It seems to use optical proximity sensing to detect the player’s hands.

A neat idea, and a slick implementation. Guardian article here…

I do feel that a lot of these devices (yes, the laser harp included) miss out on the important element of “feel” in their design. Although the laser harp project was fun, and visually very dramatic – it’s not really an expressive musical instrument.

I’ve worked on several new instrument controller designs since the laser harp, based on a variety of physical principles – and always the most successful derive their playability from some kind of electro/acoustic interaction – striking metal plates, blowing into hollow tubes, even “stroking” custom sensors (like wine glasses). The response of these sensors was then analyzed and mapped to various expression ‘dimensions’ within the tone generator. Unfortunately, moving your hands in the air has only ever been a novelty.

For that reason, I think I would trade an AirPiano – for one of these:

…and definitely for one of these:

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Jarre demo’s “Mini” laser harp at Hamburg concert

Stephen Hobley — Fri, 04 Nov 2011 17:49:57 +0000

Ricardo Melo just sent me a link to footage of Jarre’s recent gig in Hamburg. Looks like he’s added a mini laser harp to his rig.

Looks like it uses a straight “interruption” trigger built into the frame. This kind is way easier to keep under control on stage.

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…fixing up a Roland Juno 60 synthesizer

Stephen Hobley — Sun, 18 Sep 2011 13:59:42 +0000

A couple of years ago I bought a Roland Juno 60 from eBay. It was in “fairly good” condition but was very dirty and the faders did not work properly. There also seemed to be a sticky (beer?) substance on all the keys that was less than attractive. Additionally the programs weren’t being saved correctly – probably the internal lithium battery was just about done.

So I thought it was about time I opened it up and cleaned out all the gunk, and fixed the battery at the same time.

The top section is hinged, and pretty easy to open.

7 screws hold down the keyboard. Once these were removed I could remove the whole unit. Each key is held in with a tension spring – carefully unhooking these allows each key to slide out.

A quick go in the dishwasher got rid of the gunk. When you put them back check the underside, they are labelled with the correct note position for each key.

Next up were the faders, I used some Deoxit “Fader Lube” on these and got them working smoothly again.

When I replaced the keyboard, I noticed that two keys were not triggering consistently – I used Isopropyl alcohol to clean the contacts and that seemed to fix it up.

Finally I de-soldered the old Lithium battery, and tacked in a regular 3.3V button cell. The negative terminal is on top (black wire), and the positive below (green wire)

The last step was to reload the programs back to the factory defaults. There are SAVE and LOAD audio jacks on the back of the JUNO-60. Originally you hooked up a tape recorder to save program data (yes, computers used to work like that). I found wave files of the original program data online, and transferred them out through the earphone jack of my laptop into the LOAD jack on the synth. You have to fiddle with the levels but it does work (eventually).

All done! Time to take it for test drive:

The delay effect in this video was provided by a Tascam 32 reel to reel tape recorder – looping the signal from the playback head back to the record head. – It doesn’t get more analog than this!

You can get the service manual, user manual, and default programs from here.

There’s also an online version of the manual here

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At the Maker Faire in Detroit

Stephen Hobley — Sun, 31 Jul 2011 11:34:53 +0000

Spending the weekend up at the Maker Faire in Detroit.

Check out the Maker Faire Daily stream for more info.

UPDATE : Just got back from the Faire – always a pleasure to go to these, and nice that they’re more local than San Francisco now…

Wow lot’s of stuff to see and do. The Henry Ford Museum was a great venue. Many ideas for toys and games for Sarah Jane – I also managed to pick up a copy of the “Eccentric Cubicle” – a makers guide to weird and wonderful devices.

Here are some of my pictures from the event:

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Jarre at the royal wedding : 1, laser harp : 0

Stephen Hobley — Tue, 05 Jul 2011 12:54:32 +0000

I got an email from Dan Wilson about the recent Jarre gig for the Monaco royal wedding. Looks like an excellent concert, although the laser harp had some issues – and JMJ didn’t look too happy about it.

I found this video on Dailymotion (with apologies in advance for all the ads they make you sit through!). The laser harp bit is about 20 minutes in…

Jean Michel Jarre – Monaco Royal Wedding(01… by alexandru2006

It’s always a struggle getting a laser harp to function well at an outdoor event. There’s never enough smoke to see the beams properly, and when you crank it up too much you start getting false triggers – which I suspect might have happened in Monaco.

It’s interesting to hear what happens to the rest of the backing during the harp problems – the rhythm continues, but everything else stops. Glad to see that more of his music is live – I remember some discussion about his “Swatch” tour back in the early nineties about how he used a master control tape that had prerecorded music and effects sequencing.

I hope they release this concert on video – without the ads.
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Strange Wiimote camera…

Stephen Hobley — Tue, 29 Mar 2011 15:00:31 +0000

Patrick van der Poel wrote to me with some pictures of what he found when he opened up a Wiimote recently.

Instead of the normal Pixart sensor he found a strange daughter-board configuration. It looks very easy to remove, but it’s nothing like the regular sensor.

Fortunately they labelled the board pinouts on the underside of the host so it was easy to work out where the correct pins were. Patrick tells me that the Wiimote came from the Japanese market.

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How to get 100% on your Senior Project…

Stephen Hobley — Sat, 26 Mar 2011 12:26:13 +0000

Build yourself a laser harp.

At least that’s what Connor Thomas did – he’s been working on it for some time and he just sent me an email to let me know that the results came in and he scored 100%.

Nice one.

Here he is next to the tri-fold display.

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…getting one million views on YouTube

Stephen Hobley — Sat, 19 Mar 2011 21:10:51 +0000

Yay! After 3 years of ‘tubing I finally watched the view counter on my Youtube channel account click past 1,000,000 views.

Here’s the 5 most popular videos by subject…

1. The Laser Harp – got the lion’s share at 389,367 views

2. How the TARDIS really works – 23,317 views

3. Building a robotic Dalek – 16,174 views

4. How the Kinect sensor works – 12,496 views

5. “Safe” Etching Solution – 12,121 views

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