Reverse Engineering the Stylophone - WFFwiki

Introduction

The DubReq Stylophone is an icon of English innovation originally made in the UK during 1968 and famously promoted by Rolf Harris until manufacturing was stopped in 1975. The 'original' Stylophone has (since 1975) been remade several times, firstly the 'new sound' Stylophone which was based around a 555 timer oscillator and more recently as a 'retro toy' containing custom electronics.

This reverse engineering article focuses on the original (and in many people's opinion (including mine) - the best) Stylophone which was based around a programmable uni-junction transistor 'relaxation oscillator' which gave the Stylophone its unique sound. During the 1970s the 555 timer was introduced and has since completely replaced relaxation oscillators with simpler and cheaper 555 timer based square-wave tone generators.

In order to reverse engineer the original Stylophone I purchased a (broken) model from Ebay. As is very common with this type of old electronics the issue was just a build up of dirt on the potentiometers, switches and the stylus/keyboard. Here is a picture of my (repaired) Stylophone:

Hardware

Overview

There are a number of circuit diagrams of the Stylophone available on the web, however none of these diagrams seemed to match the Stylophone version I had. Researching on the web revealed that there were at least 3 versions of the original Stylophone. The first had individual resistors controlling the pitch output, then there were two further versions which used 'resistor modules' one with white modules and a later one with orange modules. The version I have is the white module version.

I found the following diagram on the web which seems to show exactly the same model of Stylophone as I purchased:

Interestingly, although the top half of the diagram matched the version of the Stylophone I had, the circuit diagram did not and seems to show an earlier variant of the Stylophone. By tracing the PCB tracks I was able to reverse-engineer my Stylophone into the following schematic diagram:

I've added some notes to the diagram explaining the functions of the various parts. Since there were no markings on the original transistors or PUT (Programmable Uni-junction Transistor) I replaced them with modern equivalents. For the PUT the choice of replacement was quite limited since there are not that many modern PUTs produced. To test the schematic I built it on a breadboard and compared the output to the original (using an oscilloscope) and the result was surprisingly close to the original. You can quite easily use the circuit diagram above to build your own Stylophone (I did and it worked well).

Relaxation Oscillator Output

Read More...
http://www.waitingforfriday.com/index.php/Reverse_Engineering_the_Stylophone

Reverse engineering a Stylophone: Reverse engineering a Stylophone - Hack a Day; Reverse Engineering the Stylophone - WFFwiki; Analog Stylophone - Hack a Day; File:Reverse Engineered Stylophone Diagram.png - WFFwiki; FindChips.com Online Electronic Component Distributor Inventory Search

Well, the name sounded familiar, from childhood. But, I couldn't quite place it. When I saw the Pic. It the Stylophone, was new to me. I'm sure that's because I grew up in the USA, TX to be exact. And the Stylophone was made and sold, for the most part, it seems, in the UK. Looks like a Pretty Cool Toy Instrument, to me. I think what I was remembering, was the Zylophone (Xylophone).

When I was a kid my MaMa (Grandma on my Dad's side). Had one like this for us to Play with at her house. I barely remember what it sounded like. But, I do remember enjoying it, when I was little.

When My kids were growing up. We had one like this for them to play with. The Sound was actually very annoying. Not a good musical instrument...

So, what do Zylophones or Xylophones have to do with Stylophones? Looks to me like, the Stylophone, is an Electronic Zylophone. And I have heard them and they can be used to make some nice Music too...

homeless man playing a zylophone

Video Link...
http://www.youtube.com/watch?v=2Io_MkBK4xI

Short Documentary on the the Zylophone Legend -Prof. GILBERT

Video Link...
http://www.youtube.com/watch?v=N_oWC55s-xU&feature=related

And there are many different types of Zylophone - Zylophones. That I had never seen before. Until Today...

Don