Touch-based Synthesizer Is A Wiring Nightmare

May 11, 2011 by Mike Szczys 10 Comments

[Jane] wrote in to let us know about the touch-based synthesizer she and her classmates just built. They call it the ToneMatrix Touch, as it was inspired by a flash application called ToneMatrix. We’re familiar with that application as it’s been the inspiration for other physical builds as well.

A resistive touch screen in the surface glass of the device provides the ability to interact by tapping the cells you wish to turn on or off. Below the glass is a grid of LEDs which represent sound bits in the looping synthesizer track. Fifteen shift registers drive the LED matrix, with the entire system controlled by an ATmega644 microcontroller. Although the control scheme is very straight forward, the jumper wires used to connect the matrix to the shift registers make for a ratsnest of wireporn that has been hidden away inside the case. Check out the demonstration video after the break to see what this looks like and sounds like when in use.

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Generating Music With Credit Cards

May 8, 2011 by Mike Nathan 19 Comments

mozarts_credit_card

[Steve] was browsing around at a local electronics surplus store when he spotted an old Tranz 330 point-of-sale terminal that seemed pretty interesting. He took it home and after disassembling it, found that it contained a Z-80 based computer. Because the 330 shares the same processor as other hobbyist-friendly devices such as the TRS-80, he figured it would be quite fun to hack.

While the Z-80 processor is pretty common, [Steve] still had to figure out how it was interfaced in this particular device. After spending some time reverse engineering the terminal, he had free reign to run any program he desired. After thinking for a bit, he decided it would be cool to use the terminal to generate music based on whatever card was swiped through the reader – he calls his creation “Mozart’s Credit Card”.

He found that just playing sounds based on the raw contents of the mag strips didn’t produce anything coherent, so he wrote a small application for the terminal based on the Melisma Stochastic Melody Generator. Music is generated somewhat randomly using various card characteristics, as you can see in the video below.

We think it’s pretty cool, but [Steve] says he’s always open to suggestions, so let us know what you think in the comments.

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Digital Audio On The Parallax Propeller

May 6, 2011 by Brian Benchoff 12 Comments

[Beth] had the idea for transmitting digital audio over S/PDIF on a Propeller a few years ago, but only just got around to a writeup. For that, we thank her.

The writeup has a marvelous walkthrough of the S/PDIF protocol and the problems associated with with generating the signal. S/PDIF is a relatively resource-intensive protocol – the signal is clocked at 64x the audio sample rate. That signal is doubled for biphase mark code, keeping everything in sync. [Beth] says the microcontroller would neet at least 24 MIPS of processing power just to generate the S/PDIF signal – processing audio would be another task altogether. Because of the processing power needed, and the weird clock rates needed, [Beth] decided to go with the Propeller. The implementation uses only one core of the Propeller, leaving another seven cores available for sound synthesis or even a visualization over VGA.

[Beth] admits this could be done with just about any microcontroller (although it would need to be clocked at a multiple of 4.096 MHz for a 32kHz audio stream), but we really appreciate the work that went into bit-banging this signal.

Video of [Nick] at Gadget Gangster playing around with digital audio on a Propeller after the break.

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Adding Remote Touch Control To The Kaoss Pad

May 2, 2011 by Mike Nathan 8 Comments

touchosc_kaoss

[Munki] enjoys using his Kaoss Pad MIDI controller to add a new dimension to his music while playing guitar. The only thing that bothers him about the Kaoss Pad interface is that it can be difficult to trigger or alter effects in the middle of a bitchin’ guitar solo. He started looking around to see if there was a way to control the Kaoss Pad wirelessly via a touchscreen and found that with a little tweaking, his iPhone was a perfect candidate for the job.

He grabbed a copy of TouchOSC from the AppStore and configured it to communicate with his computer. After building an interface for his iPhone, he taped it to his guitar and gave it a try. Everything seemed to work pretty well, but he didn’t stop there – he also wanted to control Ableton Live and Max MSP from his iPhone. It took a bit of research and some tinkering with the Live API, but he eventually got everything working together nicely as you can see in the video below.

If you are interested in trying this out yourself, he has several useful links throughout his article, and he has made his TouchOSC/Max MSP patch available for download as well.

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Quick Hack Disables IPod Dock Auto-standby

May 2, 2011 by Mike Nathan 11 Comments

ipod_dock_hacking

[Aaron] wrote in to share with us a quick hack that has made his life a little easier. He bought a Rocketfish RF-HV3 portable iPod dock to listen to his music, but he wanted to utilize it as an alarm clock as well. He also found that the speakers worked quite well when he hooked up his Yaesu handheld transmitter to the dock.

The only problem he had with it was that the dock would automatically power down when there was no input for 5 minutes. That’s fine when the dock is running on batteries, but if [Aaron] was going to use it as an alarm clock or to listen to his HAM radio, that simply wouldn’t do.

He pulled the dock apart and started poking around with his DSO Nano scope. He found that if pin 16 stays low for 5 minutes, it turns off the dock even if there is a signal coming through. His fix for the problem was actually quite simple – all he did was solder the VDD pin to the pin in question, and the 5-minute timeout was disabled.

We’re glad that [Aaron] was able to solve his problem in such an easy manner – it just goes to show what you can do with a scope and a few minutes’ time.

Single-chip Digital Audio Player

April 25, 2011 by Mike Szczys 48 Comments

[Dmitry Gr.] built a simple circuit to playback digital audio. At the center you can see an 8-pin PIC 12F1840 microcontroller. It’s pulling audio data from a microSD card which is read through a full-sized SD card adapter to which he soldered jumper wires for all of the necessary connections. There is one additional semiconductor, a FET which is used to drive the speaker seen to the left. Unregulated power is provided by a pair of AA batteries (four are seen in the picture above but only two are actually connected to the circuit). He’s planning to post his code package soon, but for now you’ll have to be satisfied with a couple of demo videos and a schematic. Both videos are embedded after the break, and we’ve also included a screenshot of the schematic which is shown in the second video.

This is very similar to the 1-Bit Symphony CD we saw almost a year ago in a links post. That one used a jewel case instead of the protoboard seen here, and had a headphone jack instead of the speaker.

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Adding A Pedal To A Yamaha DD35 Drum Kit

April 24, 2011 by Caleb Kraft 3 Comments

[Paul] Wrote in to tell us about a quick project that might be useful to others out there. He was having some problems with the DC jack on his Yamaha DD35 portable drum kit. Naturally, he did what most of us would do and just broke out the soldering iron and prepared to solder it back in place(hot glue it afterwards, that always helps too). That part isn’t a big deal, we’ve all seen it a million times. However, while inspecting the DC jack, he noticed something silk screened on the board right next to it. As it turns out, that was a kick pedal jack. After a few minutes hunting for a victim around the house that would be sacrificed for its plug, he got his hands on one. A few moments later he was jamming away with a kick pedal.

We absolutely love these super quick upgrades. [Paul] thought maybe this feature was left out at the last minute, and we’ve seen this type of thing for a number of reasons. Maybe that was a feature kept aside for a more expensive model, maybe there was some other reason it was left off. Frankly, we don’t care, we just think it is awesome that it works!

Stay with us to see a quick video demonstration.

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