the home-made MIDI-guitar
translation of Russian original of 28.12.2004
Frets and strings
Control and indications
Algorithm of note detection
|"Tryndelka"* is figurative and capacious name of
wonderful device which is, in scientific terms, a MIDI-controller in the
form of a guitar. The work is allready brought to some intermediate result which
is suitable for play.
* Russian word "tryndelka" means a female person who continuously speaks many words without necessity and sense, a she-chatterbox.
It works by the following matter:
Tryndelka -> MIDI-cable -> synthesizer -> sound
It allows to play any sound available in synthesizer - organ, piano, sax, flute, guitar, bass, percussion etc. But guitar had lost its own sound and turned into input controller.
It required a bit more than two months to make the first model, not much to look at but working. The concept was thinked out at the middle of October, and already at 20th of December 2003 this description of its first prototype had appeared on the Web. At the beginning the device used COM-port for data transfer to a computer which performed analyse of ADC-data and note detections. Then this work was transferred to onboard micricontroller (it required only a day) and Tryndelka became a full-fledged MIDI-controller. At the end of January 2004 all electronics was placed into guitar body and Tryndelka the First was completed.
Now the device allows to play on a guitar any instrumental parts, being connected to PC or synthesizer with standard MIDI cable. Velocity still is not supported. In addition to playing it allows to send simple controllers like transposition on octave or halftone(s), channel selection (separately for each string), volume, reverberation, chorus, modulation. Tryndelka can even work in "tapping mode" that could be suitable for two-handed guitarists.
Part list and pre-calculation of the cost of electronics (without guitar and PCB) indicates that all components can be purchased for ~ $40. As for PCBs, the cost of single-piece factory-made PCB is approximately $50, but it is significantly lower in case of mass production.
Firstly I recasted to a MIDI "stuffed being" an old dead 7-string guitar of my parents released in 1953. The neck is covered with a plate of 1 mm foil-clad fiber-glass plastic carrying frets - pieces of 1 mm in diameter copper conductor soldered to the cover plate - and diodes and wires on the reverse side, inside the neck. "Reincarnation 2", shown at the right, was obtained by transferring electronic "brain" to the body of another guitar, with factory-made neck cover plate and frets.
I used dissected HCM1216A beepers to make a polyphonic pickup.
Tryndelka works only with steel strings, it is required by both pickup type and principle of fret detection.
It seems to be the optimal way to take for modification a cheapest acoustic guitar of class "firewood" (which our factories are still manufacturing). Guitar corpse need to be filled with something like foam-rubber to suppress its own sound. Electronic block is inserted into the window in the deck after last spring, PCB is attached to cover plate with stands. Dimensions of PCB are 7 x 15 cm and 1.5 cm in depth.
I would be appreciated to have your advices, criticisms and proposals/suggestions. Please write me to firstname.lastname@example.org (!delete all characters between last "two" and @ sign).
Details of the project are following... Next >