The crew at the Netherlands-based Bitlair hackerspace love their music, and have set up a digital jukebox for their workshop using mpd and fookebox. One problem that you run into with a bunch of different people working in one place is that everyone has their own distinct taste in music. The rhythmic “wub wub wub” of Dubstep might be great for some while leaving others trying to solder while simultaneously covering their ears. To ensure that everyone can exercise a musical veto (a la Empire Records) now and again, they built a Skipbutton which allows members to change what’s playing.

The button allows users to skip to the next song in the queue. as well as to control the volume of the space’s sound system. It uses an Arduino pro mini to run the show, sending signals to the mpd daemon using a 433 MHz transmitter. Bitlair is pretty large and they often spend time outdoors, so they had to ensure that the Skipbutton worked wherever they did. To do this, they built a Yagi-Uda antenna at the receiving end to ensure that the button functions no matter where it’s being triggered from.

Check out their wiki if you’re interested in making a similar system for your home or hackerspace – all of the code and schematics are available for the taking.

[WaveRider] is using a type of phase shift keying called BPSK to transmit digital sound and video for remote telemetry. Though a higher signal to noise ratio (SNR) is generally sought after with communications, legal limitations are imposed on total radiated power. To balance the two headed beast, he opted out on frequency shift keying due to binary shift keying’s ability to work with lower SNR. This adds the difficulty of properly reconstructing the digital signal at the receiver. A PLL based carrier regeneration circuit is used to reconstruct the signal. Using the Rabit2000 processor as the host controller on both transmitter and receiver, 96KB/Sec serial data is obtained. On the other side of the spectrum is the Homemade regenerative tube radio.