Wind Controller Mk I

Being a lifelong saxophone player as well as an electronics enthusiast, I always thought an “Electric Saxophone” was a neat idea. In the 70’s there was a device called a Lyricon, which was basically an analog controller packaged with a traditional analog synth. In the 80’s, Yamaha came out with the WX11 and WX7, digital synth controllers that output MIDI to control contemporary synthesizers. The flute or trumpet or whatever patch you were using could now be realistically controlled using breath pressure, embouchure, and fingerings. Very cool. Later, Yamaha came out with a new model, the WX5.  Well, I like to make things, so I created my own version – my Wind Controller Mark I .

Finished System

Here are some photos of the finished system.  The wind controller body is made from baltic birch plywood and painted.  I inlaid some neat inlay stripe material on the sides.  The keytops are maple.  The interface box provides power to the instrument and is connected with an RJ-11 6 conductor cable.  The mouthpiece is made from cherry and brass.  The mouthpiece wood is finished with cyanoacrylate (CA) glue to provide a durable hypo-allergenic waterproof finish.  To carry the wind controller and supplies around I made a vinyl-covered instrument case. 

Circuit Boards

There are four main circuit boards in the wind controller.  Two boards are for the 13 top key switches.  There is another board for the bottom octave switches, option selection switches, and display elements.  The main board holds all the digital and analog circuitry.  This was all made on perfboard with soldered point-to-point wiring.  I never got around to designing a PCB for this, in fact I ended up making a whole new version of the wind controller that has far fewer parts about 10 years later – see the Wind Controller Mk II part of this website.

Layout & Design

Here you can see the overall layout of the case, switches, and circuit board.

Wind Controller Schematics

The wind controller is wired on perfboard using these schematic diagrams.  The first photo is the main processor and address decoding portion.  The main brains is an Intel 8085 processor (just like the platform robot).  The second photo is the EPROM and RAM memory. I had to use an EPROM programmer to burn the program into memory.  A software bootloader and the ability to run from RAM was essential in development of the operating software.  Once I had things running right, I relocated the code to the ROM area and burned the EPROM.  The third photo has the analog and discrete switch input multiplexers.  A Maxim MAX188 A-to-D converter handles the sampling and conversion of the various analog inputs.  The key switches are multiplexed using 74244 bus buffers.  The Intel 8251 serial interface Universal Asynchronous Receiver-Transmitter (UART) used for MIDI communication is shown on the fourth photo.  There’s also a Maxim RS232 driver chip which allows the wind controller to use the same UART to communicate with a computer instead of a MIDI sound module.  An ICM7218 7-segment LED driver is used to drive the 4 digit program/status display on the bottom of the unit.  The last photo shows the analog buffering and amplification circuitry for the breath pressure sensor, lip pressure sensor, and thumb pressure sensor.  The breath pressure sensor is a bridge-type gage sensor.  The lip and thumb pressure sensors are force sensitive resistors (FSRs) from Interlink Electronics.  The opamps are low power devices from Maxim, and there’s a +/-10V charge pump chip to generate the bipolar voltages needed from the main system 5V supply.

Interface Box Schematic

Here’s the interface box schematic.  It contains the 5V power supply as well as a switch to change between the MIDI and RS232 output modes.  The footswitch input is for a pedal connection that can be used by the wind controller software to sustain notes, create a drone like a bagpipe, engage an interval mode, and so on.

Comments are closed.