Pandora＇s Sound & Music Box

Published:2011/7/25 22:07:00 Author:Phyllis From:SeekIC

By Ken Bromham

Recycle an old CD-ROM drive for (triggered) playback

This project was originally conceived for model making applications as a cheap way to provide high quality audio playback in response to a trigger signal (typically from a pushbutton or PIR detector), but we’re pretty sure Elektor readers can find many other uses.
The standard low cost solution to creating auto-playback sounds is to use a record/playback chip (say, the ISD25XX series) but these devices are limited to about 3 kHz audio bandwidth, not to mention a lot of hiss and noise, so the sound quality is not the best unless you’re specifically after for voice messages of the Stephen Hawking type.

The Elektor approach

Over the past few years we have received many requests from readers asking for a circuit that would allow them to use an old CD-ROM player for the sole purpose of playing back music CDs. In many cases, that is possible just by connecting a power supply and headphones to your drive, inserting a CD and pressing the Play button. Simple as this may sound, there are pitfalls, particularly with later CD-ROM drives that do not have a music playback button. Also, we really could not stand the thought of being unable to select and skip tracks, etc. In true Elektor fashion we wanted to be in control of things and make the old CD-ROM drive do something really useful. The alternative approach developed by Ken Bromham and described in this article makes use of a 40-pin PIC 16F87X microcontroller which, helped by a small number of external components, provides a versatile controller module that will interface to any old ATAPI CD-ROM drive. Mind you, ATAPI is not a brand, but a connectivity standard for 99% of all CD-ROM drives in PCs for home and office use. Don’t worry about it, just start rummaging around in the attic or cellar, dig a CD drive out the IT skip at work, or commandeer the oldest (usually read only) CD drive from the kiddies’ PC leaving a note saying ’drive removed for scientific purposes’. Never tell them you got the idea from Elektor, instead, tell them to keep using the CD/RW drive which is much faster, better, etc. or better still buy them a mini MP3 player and headphones.

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