{"id":837,"date":"2013-01-16T21:29:54","date_gmt":"2013-01-16T20:29:54","guid":{"rendered":"https:\/\/andyland.info\/wordpress\/?p=837"},"modified":"2018-09-16T16:35:35","modified_gmt":"2018-09-16T15:35:35","slug":"harddisk-turntable","status":"publish","type":"post","link":"https:\/\/andyland.info\/wordpress\/harddisk-turntable\/","title":{"rendered":"Harddisk Turntable"},"content":{"rendered":"

This is my attempt to build a Midi turntable (a.k.a. Jogwheel) from an old harddrive.<\/p>\n

Some time ago I came across this (rather famous) article:<\/p>\n

A hard drive hacked into a turntable<\/a><\/p>\n

What they basically did here is to take an old harddrive and connect the motor via a set of op-amps to a microcontroller. When the platter is moved the motor (now actring as a generator) will produce signals that can be analysed by the \u00b5C and used for generating Midi out.<\/p>\n

So far so excellent. But the deeper I got into the topic the more it became clear that this wasn’t the best solution for me since the article states that very small and slow platter-motion isn’t detected reliably.<\/p>\n

That’s why I started building my own version of a harddisk turntable using the optical sensor of an old mouse.<\/p>\n

Here we go, it all starts with an old harddisk<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

I have been dealing with computers for more than 20 years now but this is the only harddisk I had ever problems with. And this probably wasn’t caused by one of those “ooh my god…my harddisk suddenly crashed”-moments ismply but due to accidentally dropping it while moving to another flat.<\/p>\n

So – this is the first time ever that I’m taking apart a harddisk….<\/p>\n

\"\"<\/p>\n

I figured out that I had to get rid of two platters because it would make the construction too heavy an dull-feeling.<\/p>\n

\"\"<\/p>\n

In order for the optical sensor to be able to detect the platter being moved I taped the edge of the platter to give it some structure.<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Fortunately the harddrive motor could completely be detached from the housing. This way I can use it in another case<\/p>\n

\"\"<\/p>\n

The mouse was a Logitech RX250 that I had lying around<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

The sensor is of type A5020E. Fortunately I found an Arduino library for this device over here<\/a>. It’s a little bit old and in order to make it work under Arduino 1.0.1 you have to exchange<\/p>\n

#include “WConstants.h” \u00a0 \u00a0 \u00a0\u00a0 against<\/p>\n

#include “Arduino.h”\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 in the .cpp file. That’s all.<\/p>\n

I simply desoldered the sensor and put it on a scrap piece of vector board. This will later be fixed by hotglue-influenced-technology =). the datasheet can be found here<\/a> or here<\/a> (if the original site will change or be offline).<\/p>\n

\"\"<\/p>\n

During the first attempts I found out that it’s a good idea to keep the clear piece of plastic together with the mouse’s original LED in order to have the right conditions for the optical sensor’s illumination. For that reason I cut an appropriate hole into the new case.<\/p>\n

It is pretty save to say that I am by far one of the worst craftsmen around….<\/p>\n

\"\"<\/p>\n

Because I left away two of the three harddisk’s platters I had some space that needed to be filled up. This piece of foam comes from inside the old harddisk<\/p>\n

\"\"<\/p>\n

\"\"<\/p>\n

Some hotglue later<\/p>\n

\"\"<\/p>\n

At the moment the circuit only exists on an Arduino breadboard. I will fix this later<\/p>\n

\"\"<\/p>\n

Proof of concept<\/p>\n