Description:

This is a simple MIDI keyboard designed for use with standard PC soundcard with MIDI/Game connector. Keyboard is powered directly from Game port an there is no need of power supply unit, and no high voltage risk. If you need to use it as standard MIDI device, you should build (or buy) a proper power supply and opto-isolated MIDI output buffer. You could find more information about such buffer module on MIDI Technical Fanatic's Brainwashing Center under Hardware projects topic.

The schematic design is based on most popular PIC16F84 (or PIC16C84) single-chip controller by Microchip. It supports up to 64 keys without velocity sensing. I used keyboard from an old analog instrument, just adding a swich under every key and wiring swiches to connect them as shown on schematic below.

Used parts:

U1: PIC16F84. Can be used PIC16C84. The difference is that the first one has Flash memory, and the second has EEPROM memory. There is no difference in way they are used in such designs.
U2: 74LS138. This is TTL decoder 3:8 used for key rows scanning.
Q1: Quartz resonator. Must be 4MHz.
C2,C3: Capacitors 27pF each. Certain quartz resonators have these capacitors integrated. If you use such resonator, there is no need of C1 and C2.
R1..R3: Resistors 1..10 k. Used to hold up certain IC pins. I use 1.8 k.
R3: Resistor 270 Ohms to protect MIDI output from shortcut.
Diodes: Each key has serially connected diode to prevent keycrossing when more than one key is pressed on keyboard. These can be any type of standard diodes.
P1: An DB15 male connector.
JP1: Jumper or moment action Button, depending on HEX file version.

Embedded software:

It is NOT enough to build this schematics in order to use it. An necessary part is embedded program. I wrote it using Mpasm by Microchip. I put here the hex code produced by Mpasm (this is ready to use object code). By clicking on coloured text you can download whole project (basic version) along with some additional information and programs.
During the project developing a number of consequent versions of HEX files have been released. The list of these versions is given below. Clicking on list items you can download selected versions (in zip format). Downloaded archive files contain explanations text file, hex file and schematic diagram of device.
You'll need a PIC programmer in order to burn the HEX file into PIC. The programmer is very simple and easy-to-make unit. The first programmer I used is here (ZIP), the one I'm using now is here (PDF).

MKC VERSIONS:

Some of downloaded files (PDF format) require Adobe Acrobat Reader. You can download it for free by clicking on the link above or the banner below.

Construction:

Here you can see pictures of MKC prototype and my first keyboard. Nothing more to say...

You made it:

Some of realizations of MKC made by you are shown below. All materials are published under kindly agreement of their authors. Publishing these materials could help more people to build and use MKC.

NOTE:All designs shown below will work using original firmware published on this site (see Embedded software ).

Igor Popov from Ukraine (his site here) developed nice printed circuit board (PCB) using OrCad package under DOS. Pictures below show photo and screenshot of PCB design. More detailed graphic files about Igor's PCB design could be downloaded from here. Schematic files are included in order to track changes made in parts names. Thanks, Igor.

The next passion of Igor is VRML (Virtual Relity Modelling Language). Here is an projection of his 3D model of the PCB shown above.

More things about Igor's work and VRML can be found on Igor's sites:

The VRML demo can be downloaded directly from Igor's site here. If would require VRML plug-in installed in your browser. Plug-ins and many other things about VRML modelling can be found here (site in Russian).

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Vern Jones from USA (his site here) developed his project using Visio package. His design supports PC soundcard and standard MIDI devices as well. Shown is photo of Vern's design. You can download the full files set from here. Schematic file is included.
Vern has also kindly provided original documentation of his design in DOC (M$ Word) format. You can download it from here. There are all graphic originals of PCB's and schematic descriptions. The documents for these PCBs can be printed thru M$ Word on a lazer or inkjet printer. They will print out in the correct scale (1:1) on clear mylar to make direct photo boards. Thanks, Vern.

Vern also provided a picture of his Rodgers Trio organ. He added MIDI scanners based on MKC to organ's Middle manual and Pedalboard. Similar scanners will be added to Upper and Lower keyboards also and maybe one more for scanning tab stops (the red and white bars seen on picture). I'm proud with MKC working good in this nice instrument. Thanks again, Vern :-)

Here is Vern's Pedalboard Controller used in his organ:

Continuing development of this line of units, Vern also made Stop Tab/Switch Controller unit for controlling famous Ahlborn Archive classic organ emulator. This design was also based on MKC.

That is how the ready Ahlborn control unit looks outside:

You may order the units shown here directly from Vern. More information can be found on Vern's site. Here is functions table for this unit (zipped Excell'97 worksheet).

Pedalboard Controller and Stop Tab/Switch Controller were ordered and assisted by Jerry Cluff, another MIDI/pipe organs dedicated person. You may find more information about ordering/purchasing these units and many more organ related goodies on Jerry's site. Here is the second one of his sites.

Here are two more Pedalboard Controllers - 13 and 25 pedals.

Another popular MIDI expander - D110 by Roland has its Stops Control Unit, based on custom version of MKC, thanks to Vern again. Here si how it looks:

It can control up to 4 D110 units, set on different MIDI channels.

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Nik 'Rebuzz' from Russia embedded MKC into his second (5 octaves) keyboard . Here is a picture of his studio. MKC based keyboard is the one below the computer keyboard. Thanks, Nik.

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Paolo Airasca from Italy started his own modular keyboard scanner design. CPU unit based on MKC is shown here. The decoder chip (74LS138) is placed on another PCB, built-in in the keyboard unit for cabling minimizing. This kind of design is very flexible. It allows expanding the system by adding similar keyboard units and replacing only the CPU unit with more capable one (mkc128 or upper). Thanks, Paolo.

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Gerrit Lammertink from Netherlands (his site here) built his own 5 octave MIDI keyboard based on MKC, using parts of an old electronic organ. Here you can find full information on his keyboard (pictures, schematic, PCB, instructions etc.). Thanks, Gerrit.

Here is another project of Gerrit made by old PC keyboard plus MKC unit. Gerrit added chord keys besides the normal keys. Chords keys are 'hard wired' to a number of major chords that can be played by clicking single chord key in accordion-like way. Thanks Gerrit for giving me the idea about adding chords implementation in MKC project.

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Marco Tavan from Italy recovered an old 61 keys Orla DMK5 keyboard for using it with B4 Hammond organ emulator software by Native Instruments. Marco used MKC plus additional multyplexer, in order to use standard common rail keying instead matrix keying. Bravo, Marco.

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Here is an interesting gadget whose hardware design is based on MKC. Paul Everett (his site here) wrote his own firmware for this. You can design such device using Paul's software as well as MKC native firmware. The original instrument that inspired this project was named Hayden Duet Concertina. I've never heard about it before but does this have a matter :-)

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Ron Fleming got a pedalboard from an old Lowery Organ and after redesigning its contact system and adding MKC, here is how his rig looks. Thanks, Ron.

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Pierre from France has built another exotic MIDI controller incorporating MKC in Nintendo game pad. Here is the picture.

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If you have made your version of MKC and want to place here its photo, just e-mail me .