DJ Scratches Out Club Music With Tape, Not Turntables

It goes without saying that not everyone has the same taste in music, and what sounds amazing to one person will be the next person’s noise. But even if you’re not into hip-hop and the whole DJ scene, it’s hard not to be impressed with what [Jeremy Bell] has done here with his homemade tape loop “scratching” rig.

Most people have probably seen a DJ in a club using dual turntables to scratch or “scrub” a vinyl record back and forth to create effects that add to the music. Part musician and part performance artist, DJs and “turntablists” tend to be real crowd-pleasers. [Jeremy]’s “ScrubBoard” uses a loop of 2″ audiotape, the kind recording studios once used for multitrack recordings. The loop is driven across a wide platen by a motor with a foot pedal control, which he can use to quickly reverse the direction of travel and control the speed of the tape. A pair of playback heads are wired into the amplifier and can be positioned anywhere on the sometimes moving, sometimes stationary tape. The sounds he can create are rhythmic, percussive, and at times frenetic, but they’re always interesting. Check it out in action in the video below.

This version of the ScrubBoard is far from the first [Jeremy] has built. You may recall his first prototype from our coverage in 2014; that one used just a few feet of 1/4″ tape fixed to a board. He was still able to get some great sounds from it, but this version should really change things for him. 

Continue reading “DJ Scratches Out Club Music With Tape, Not Turntables”

Recording Off A Reel-to-reel With A Credit Card Reader

If you’ve got a few reel-to-reel recordings of 1940s radio, how do you transfer those to a digital medium? [Evan Long] and his dad used a credit card reader built for the iPhone to transfer a vintage [Art Kassel] recording from magnetic tape to the digital domain of .MP3s.

A few months ago, we saw what goes into these Square credit card readers. They’re just a magnetic tape head with a resistor an 1/8″ jack that plugs directly into the headphone jack of any iDevice. Because there’s no hardware limitation of what the Square credit card reader can do, [The Long boys] decided to back up some old reel-to-reel tapes with an iPod Touch.

[Evan] and his father needed to perform a few modifications to the credit card reader; the tape head pressed against the plastic case too tightly to allow feeding 70-year-old tape through the device. After bending a bit of metal the credit card reader was ready to record the dulcet tones of the Big Band era.

It’s a neat build, and anything that reuses proprietary hardware (however limited) is alright in our book. Nice job, guys.

Reading Credit Cards With A Tape Head

A company called Square is giving out free credit card readers that turn any iPhone or iPad into a Point of Sale terminal. [Steve] got a hold of one of these tiny peripherals and did what any sane person would do: tear it apart and learn how it works. This bit of hardware is a little unimpressive; unsurprising because Square is giving them away. With simplicity comes an ease in understanding, and [Steve] was able to successfully read his own credit card with this tiny and free credit card reader.

[Steve]’s work in decoding credit card data builds off [Count Zero]’s article from the bbs days. Basically, each credit card has two or three tracks. Track three is mostly unused, whereas track one contains the card holder name, account number, cvc code and other ancillary data. Track two only contains the credit card number and expiration date.

The only components in the Square card reader are a head from a tape player and a 1/8″ microphone jack. The magnetic head in the Square card reader is positioned to only read track two. With a small shim, it’s possible to re-align the head to get the data from track one. After recording an audio file of him sliding his card though the Square reader, [Steve] looked at the number of times the waveform flipped from positive to negative. From this, he was able to get the 1s and 0s on the card and converted them to alphanumeric using the 6-bit ANSI/ISO alpha format.

[Steve] isn’t going to share the code he wrote for Android just yet, but it should be relatively easy to replicate his work with the Android tutorial he used. Also, yes, we did just pose the question of how these Square credit card readers work just hours ago. Good job being on the ball, [Steve]. Tips ‘o the hat go out to [Bobby], [Leif], [Derek] and anyone else we might have missed.

EDIT: [Stephen] sent in his teardown minutes after this post went live. Hackaday readers are too fast at this stuff.