Pair of musical hacks use sensor arrays as keyboards

sensor-driven-musical-keyboards

This pair of musical keyboard hacks both use light to detect inputs. The pair of tips came in on the same day, which sparks talk of consipiracy theory here at Hackaday. Something in the weather must influence what types of projects people take on because we frequently see trends like this one. Video of both projects is embedded after the jump.

On the left is a light-sensitive keyboard which [Kaziem] is showing off. In this image he’s rolling a marble around on the surface. As it passes over the Cadmium Sulfide sensors (which are arranged in the pattern of white and black keys from a piano keyboard) the instrument plays pitches based on the changing light levels. [Thanks Michael via Make]

To the right is [Lex's] proximity sensor keyboard. It uses a half-dozen Infrared proximity sensor which pick up reflected light. He calls it a ‘quantised theremin’ and after seeing it in action we understand why. The overclocked Raspberry Pi playing the tones reacts differently based on distance from the keyboard itself, and hand alignment with the different sensors.

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Infra is a television made of Infrared pixels

ir-television-using-625-tv-remotes

This television is perfect except for its low resolution and the fact that it can’t be seen by the naked eye. [Chris Shen's] art installation, Infra, uses 625 television remotes as pixels for a TV screen. There’s a little bit of insight to be gained from the details which [Chris] shared with EMSL.

The remote controls were all throw-aways. Even if there are problems with the buttons, battery connectors, or cases, chances are the IR led in each was still functional. So [Chris] patched into them using about 500 meters of speaker wire.

Why 625 pixel? Because that’s how many LEDs the Peggy board can handle. We’ve seen this open source LED board driving video in other projects. Here it’s been connected to each remote using Molex connectors. Each of the headers has the same pitch as a through-hole 5mm LED. The entire board was filled with them, and a mating crimp connector terminates the end of the wire coming out of each remote. This makes setup quite easy as the remotes don’t have to be installed in any particular order as long as the physical location matches Peggy’s grid.

You can get a glimpse of the piece playing video in the clip after the break.

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Communication protocol for an indoor helicopter

propel-execuheli-ir-protocol-revealed

There’s a special type of satisfaction that comes from really understanding how something works at the end of a reverse engineering project. This grid above is the culmination of [Spencer's] effort to reverse engineer the IR protocol of a Propel ExecuHeli indoor helicopter toy.

The first thing he looked at was the three different controller channels which can be selected to allow multiple helicopters to be used in the same area. [Spencer] was surprised that they all used the same carrier frequency. The secret must be in the coded packets so his next challenge was to figure out how the data was being transmitted via the Infrared signal. It turns out the packets are using pulse-length coding (we were unfamiliar with this protocol but you can read a bit more about it here). The last piece of the puzzle was to capture packets produced by each unique change of the control module. With each bit (except for bit 11) accounted for he can now format his own codes for a controller replacement. Perhaps he’s looking to make the helicopter autonomous?

Digital IR Theremin

Digital IR Theremin

This Digital IR Theremin creates tones based on the distance of an object from its IR sensor. There’s no microcontroller here, since the project is part of an Introduction to Digital Electronics course. Instead, it uses a handful of comparators, transistors, AND gates, and a 555 timer to make noise.

The comparators are connected to create window comparators. This configuration will output a digital 1 if the input is between two reference voltages, and 0 if it is not. Using this, the analog output of the IR range sensor can be converted to digital values.

The 555 timer takes care of creating the output waveform. A specific resistor is switched in to the timer’s RC circuit depending on which window comparator is active. This allows for a different tone to be played depending on the distance from the IR sensor.

The result is a square wave, which has a frequency dependant on how close an object is to the IR sensor. By selecting the right resistances for each distance, the theremin can be tuned to play a specific scale.

This is a neat project for people looking to learn digital electronics, and the write up does a great job of explaining the theory. After the break, check out a video of the theremin generating some tones.

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More Fun with Syma 107 Reverse Engineering

Syma Reverse Engineering

[Jim] used a logic analyzer to do some in depth analysis of the Syma 107G helicopter’s IR protocol. We’ve seen work to reverse engineer this protocol in the past, but [Jim] has improved upon it.

Instead of reading the IR output of the controller, [Jim] connected a Saleae Logic directly to the controller’s circuitry. This allowed him to get more accurate timing, which helped him find out some new things about the protocol. He used this to create a detailed explanation of the protocol.

One of the major findings is that the controller used a 3 byte control packet, which contradicts past reverse engineering of the device. There’s also a new explanation of how multiple channels work. This allows multiple helicopters to be flown without the controllers interfering.

The write up is quite detailed, and explains the reverse engineering process. It also provides great information for anyone wanting to hack one of these low cost helicopters. From the details [Jim] worked out, it would be fairly easy to implement the protocol on your own hardware.

Autonomous helicopter works like a Wii remote

autonomous-ir-helicopter

[Jack Crossfire] took one of those inexpensive indoor helicopters and made it autonomous. He didn’t replace the hardware used for the helicopter, but augmented it and patched into the remote control to make a base station.

The position feedback is provided in much the same way that the Wii remote is used as a pointing device. On the gaming console there is a bar that goes under the TV with two IR LEDs in it. This is monitored by an IR camera in the Wii remote and used to calculate where you’re pointing the thing. [Jack's] auto-pilot system uses two Logitech webcams with IR filters over the sensors. You can see them mounted on the horizontal bar in the cutout above. The helicopter itself has an IR LED added to it that is always on. The base station follows this beacon by moving the cameras with a pair of servo motors, calculating position and using it when sending commands to the remote control’s PCB.

Don’t miss the demo video of the rig after the break.

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Beefing up a smoke alarm system with video, temperature, and connectivity

Here’s a little smoke detector hack which [Ivan] has been working on. He wanted to extend the functionality of a standard detector and we’re happy to see that he’s doing it with as little alteration to the original equipment as possible (this is a life-saving device after all). He sent all the build images for the project to our tips line. You’ll find the assembly photos and schematic in the gallery after the break.

As you can see his entry point is the piezo element which generates the shrill sound when smoke as been detected. He connected this to his own hardware using an optoisolator. This allows him to monitor the state of the smoke alarm on his server. It then takes over, providing a webpage that display’s the board’s temperature sensor value and streams video from an infrared camera.

Of course this is of limited value. We’ve always made sure that our home was equipped with smoke detectors but the only time they’ve ever gone off was from normal cooking smoke or after an extremely steamy shower. But still, it’s a fun project to learn from and we’ve actually got several of the older 9V battery type of detectors sitting in our junk bin.

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