Drawn In By The Siren’s Song

When I say “siren” what do you think of? Ambulances? Air raids? Sigh. I was afraid you were going to say that. We’ve got work to do.

You see, the siren played an important role in physics and mathematics about 150 years ago. Through the first half of the 1900s, this fine apparatus was trivialized, used for its pure noise-making abilities. During the World Wars, the siren became associated with air raids and bomb shelters: a far cry from its romantic origins. In this article, we’re going to take the siren back for the Muses. I want you to see the siren in a new light: as a fundamental scientific experiment, a musical instrument, and in the end, as a great DIY project — this is Hackaday after all.

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Analog Clocks Play Their Own Beat

Play the demo video below and try not to let the rhythm worm its way into your brain. What you’re hearing is the sound of a bunch of clocks, amplified. None of them are keeping wall time, but all of them are playing together.

[Gijs] makes crazy musical instruments. He doesn’t give us much more than a video and a couple schematics for this project, so this one’s still a bit of an enigma, but here’s what we’ve put together.

Klok slave unit schematic
Klok slave unit schematic

The video looks like eight identical version of the same module. The input takes a voltage and converts the rising and falling edges into pulses to drive the coil of an el-cheapo clock. The LEDs pulse as the poles of the clock switch to the incoming beats. The output comes from an amplified piezo sensor stuck on the back of each clock. That is, what you’re hearing is each clock ticking, but amplified. And if you watch the dials spin, it doesn’t look like any of them are telling time.

So far so good, and it matches up with the schematic. But what’s up with that switch on the front? It doesn’t show up anywhere.

And what’s driving the show? [Gijs] tantalizes us with a master clock module (on the same page) that looks like it does keep time, and outputs subdivisions thereof. But that would be too slow to be what’s used in the video. Has he swapped the crystal to make it run faster? It’s a mystery.

Of course, we’d expect no less from the man who mics up a kitchen timer or a gear motor and adds them to his synthesizer rack. We’ve covered a bunch more of [Gijs]’s work in the past, from his video mixers to this hard-drive turned synth oscillator, but this time he’s got us scratching our heads a bit, as well as tapping our feet.

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We Salute The Television Tube Flag

From [Gijs] comes Beeldbuis Vlag Tijsdlijn, or television tube flag (Translated). We’re not up on our Dutch, but it appears that [Gijs] and friends have created a television tube which waves much like a flag in response to airflow from a fan.  The effect is pretty darn amazing, and that’s putting it mildly. To create this hack, [Gijs] built a modified Wobbulator. The Wobbulator is an early video synthesizer which used added steering coils to modify the operation of a standard TV tube. When excited, the coils would deflect the tube’s electron beam, causing some rather trippy images to appear on-screen. (Yes, here at Hackaday “trippy” is a scientific term).

[Gijs] wanted his screen to be “waved” by a fan, just like a flag would wave. To do this he used an anemometer made of ping-pong ball halves. The anemometer spins up a DC motor from a CD-ROM drive. In this application, the motor acts as a generator, creating a DC voltage. An ATmega328 running the Arduino code reads the voltage from the motor. If the anemometer is spinning, the Arduino then outputs a sinusoidal value. The Arduino’s output is amplified and applied to the coil on the CRT. A network of power resistors ensures the amplifier is correctly loaded. The results speak for themselves. In the video after the break, the tube flag is displaying a slide show of photographs of its construction. As an added hack, [Gijs] used an Arduino Leonardo as a USB keyboard. When the anemometer spins, the primary ATmega328 sends a signal to the Leonardo, which then emulates a push of the arrow keys on the host computer. This lets the tube flag advance its own images. Very cool work indeed!

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A Modular Game Boy Synthesizer


Synth heads and electronic music aficionados the world over love a good rackmount synth. These days, though, synthesis tends more toward small, digital, and ‘retro’ rather than the monstrous hulking behemoths of the 60s and 70s. [gieskes] might be ahead of the curve, here, as he’s built a Game Boy module for his eurorack synthesizer.

The software running on [gieskes]’s Game Boy is the venerable Little Sound DJ (LSDJ), the last word in creating chiptunes on everyone’s favorite 8-bit handheld. As with any proper Game Boy used in chiptunes, there are a few modifications to the 1980s era hardware. [gieskes] tapped into the cartridge connector with a ‘repeat’ signal that provides slowed down, noisy signals for LSDJ. There’s also pitch control via CV, and the audio output is brought up to 10Vpp

In the video below, you can see [gieskes]’ euroboy in action with a few Doepfer synth modules. There’s also a very cool pulse generator made from an old hard drive in there, so it’s certainly worth the watch.

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Hackaday Links: January 17th, 2013

Free-formed VFD clock

links-free-formed-vfd-clock [James] doesn’t need a circuit board or even some protoboard to get the job done. He free-formed all the circuits for his VFD clock. Right now this is the only project hosted on his blog so click around to see how he got to this point.

DIY LED traffic light


Here’s a scratch-build traffic light which [Jarle] uses to display information about his server. If you’re unable to find your own storm damaged original this is a pretty easy way to build one.

FPGA space attack game


This game is running on an FPGA, but it’s not written in HDL. Instead, [Johan] wrote the game in C to run on a soft processor loaded on the gate array.

Hourglass entropy


This is a fascinating idea for generating random numbers. [Gijs] is shining a laser onto a light dependent transistor. The beam of the laser is broken by the falling sand of an hourglass. This technique could be use as an entropy source for random number generation.

GPS clock source for a digital timepiece


It seems like massive overkill, but you can’t beat the time accuracy of using a GPS module as a clock source. We don’t expect that [Jay] kept the clock in one piece after finishing the project. It’s just a good way to practice decoding the GPS data.

Adding A Sound Synthesizer To A ‘don’t-touch-the-sides’ Maze Game

Part of the fun of the classic game of Operation is the jump you get from the loud buzzer which sounds if you touch the sides. This exhibit piece uses the same principle of lining the edges of a track with metal, but instead of an annoying buzz, each touch will issue a bit of music. That’s because the maze has been paired with a synthesizer. Instead of one sound wherever the stylus touches the sides, different parts of the maze act as one of 94 keys for the synthesizer.

There’s a lot more built into the base of the device than just a maze game. The knobs are used to alter the audio effects and the buttons work in conjunction with they stylus to sequence audio samples. There’s even a graphic LCD screen which shows the currently playing wave form. You can get a better look at the project in the video after the break.

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Mixing Video For Old School Effects

For all the high production values Final Cut Pro and Adobe Premier have released upon the world, there’s still a cinematographic aesthetic only possible with analog video, linear editing, and video feedback. [gijs] just sent in a video mixer he’s been working on to allow crossfading between two video signals and introducing some very cool analog video distortion effects.

[gijs]’ mixer uses the LM1881 video sync separator also found in the Arduino video experimenter shield. Because two different video feeds are unlikely to send their sync signal at exactly the same time, the selected video will stay still on the screen while the second video feed will slowly scroll horizontally across the screen.

This isn’t the first analog video hack [gijs] has come up with; last year he released an Arduino video sampler capable of recording about a second of video and playing it back forward, reverse, looped, or inverted.

We’re sure combing both the video mixer and sampler would produce an aesthetic similar to the experimentation seen on 80s-era public access or our time in AV club. Either way, a very cool build that just can’t be done digitally.

Video of the mixer after the break.

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