Echolocation pinpoints where a gunshot came from


[Kripthor] suspected that hunters were getting too near his house. When thinking of a way to quantify this belief he set out to build a triangulation system based on the sound of gunshots. The theory behind it is acoustic location, which is a specialized type echolocation.

The most common example of echolocation is in Bats, who emit ultrasonic noise and listen for its return (echo) to judge the location of objects. [Kripthor] doesn’t need to generate the sound himself, he just needs to pick it up at different points. The time difference from the three samples can be used to triangulate coordinates as seen in the image above.

He first tried using a PC sound card to collect the samples. The stereo input only provides two channels so he tinkered around with a 555-based multiplexing circuit to sample from three. The circuit noise created was just too great so he transitioned to using an Arduino. The ADC samples from each microphone via an NPN transistor which is used as a simple amplifier.

This brings to mind a homebrew sonar hack from way back.

Voice controlled video game uses “Biu” and “ahh” for control


This video game gives your thumbs a rest while stretching those vocal chords. The pair of microphones seen above control the video game on the LCD display. Saying “Biu” will launch a projectile while “ahh” adjusts the flight path. The system was developed by [Tian Gao] as a final project for his ECE 4760 course at Cornell University.

The inputs are common computer microphones connected to some processing circuitry which he built on a piece of protoboard. This consists of some RC filtering and an LM358 opamp to get the signal ready for use with the ATmega1284. There is only one ADC on that chip so [Tian] alternates sampling from the microphones by using the multiplexer built into the chip. The video signal itself is an NTSC composite signal. To facilitate a reasonable frame rate he uses graphics that are packed in multiples of 8-bits. All in all this allows him to create a 160×200 pixel display.

All of this makes the game sound a little dry, but we dare you to listen to the video clip after the break without cracking a smile.

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How to add audio in to the Sony NEX-5 line of DSLR cameras

[Tynan] loves his Sony NEX-5 camera but he’s fed up with not being able to choose any external microphone when recording video. Recently he set out to remedy that, and managed to add an audio in jack without modify the camera itself.

The real trick here is to modify how a microphone accessory connects to the camera. In [Tynan’s] tutorial video (embedded after the break) he uses the enclosure from a flash module as a connector. After removing the electronics he’s left with plenty of room for the guts of a Sony microphone accessory. Those include the PCB and wiring, but not the microphone element itself. A 3.5mm audio jack is added to the flash case, and soldered to the microphone cable. Now he has a modular audio-in jack. The only problem is that his tinkering resulted in mono only. If you don’t mind spending a bit more time reverse engineering the scrapped microphone we bet you can parlay that into a true stereo option.

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Roll your own parabolic microphone

Parabolic microphones are used to listen in from a distance. You see them on the sidelines of NFL football games, but they’re part of the standard issue in detective and spy novels. Now you can build your own parabolic microphone by following this example.

The one component that may be hard to find is the parabolic reflector. You cannot simply use a bowl or other curved object as the precise parabolic shape ensures that sound waves are reflected onto one finite focal point. For this build the reflector was obtained from an eBay seller. But the other parts are scavenged from easy to find sources. The microphone itself is an inexpensive element from Radioshack. It is mounted in the shell from a tweeter speaker, which helps to gather the sound if the element isn’t exactly aligned with the focal point. The setup also needs a preamplification system, which uses many components. Luckily there’s a schematic and other reference material linked in the write up.

You can also build a laser microphone which detects sound waves on a pane of glass.

[Thanks Anonymous]

Morse Code interpreter

[Sulaiman Habsi] and two classmates put together a Morse Code interpreter as a class project at Sultan Qaboos University. The system listens to a morse code signal using a microphone, then translates that input to text which is displayed on this character LCD.

The breadboarded circuit feeds an audio signal from the microphone, through an OpAmp, to the ADC of an ATmega8 microcontroller. The captured signal is stored as a byte in a special way. The three least-significant bits signify how many total dots or dashes are contained in the character, the remaining bits represent those dots and dashes with zeros and ones. A full description of this process is included in a PDF linked in the article above. As you can see in the video after the break, the hardware waits to process all of the signals once the full message has been received.

This would be a great add-on for a Morse Code practice keyer.

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Schäuble Jr Aims to Take Away Your Privacy!

[Mnt] wrote in to tell us about this 360 degree array of cameras featured on [Codeninja]. This has to be one of the most impressive arrays of cameras and sound equipment that we’ve seen at Hack a day.

The array is capable of 360 degree x 140 degree panoramic views using the 9 cameras arranged in a circle around the base. Impressive in itself, these cameras are all capable of both pan and tilt rotation via and Arduino-controlled servo setup. It also has a native 360 degree camera mounted on top of everything for calibration purposes and IR-LED illumination capabilities.

On top of all of this, the camera array also features audio capability with a 9-microphone setup, presumably one for each camera. This, coupled with piezoelectric speakers should provide for echolocation capability. Although jokingly called the “Schäuble Jr.” after a German politician, we’re not sure of the true purpose for this “sensor array.” We can only hope that it will be used for good. A very impressive build, it will be interesting to see what comes of it.

A badge without a conference

We saw this one a few days ago when it was first bouncing around the interwebs but never took a close look at it. Today, when we ran across a direct link in the tips box it was the promo video (embedded after the break) that won us over. Once you dig into the particulars of The Verbalizer we think you’ll agree that this is a hackable conference badge without the pesky need to attend a conference.

As you probably guessed from the design of the PCB, this is a microphone. It’s intended for use with Google’s new voice search feature, and connects to a computer via a Bluetooth module. But really it’s just another roll-your-own Arduino with a few extra bits. You’ll find an ATmega328 and an FTDI chip which provides a USB connection for programming. The real fun starts with the microphone and speaker circuitry which is just waiting to be breadboarded at home. We found a few other things while poking around in the schematic (available by downloading their Product Docs and Schematics package). It looks like there’s some capacitive touch… you what? Isn’t it more fun if you find this stuff yourself, kind of like the hidden gems of the DEFCON badges?

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