Guitorgan

A Guitorgan is an electric guitar with electronic organ components added. Each guitar fret is separated into six segments, creating independent contact switches for each string. The organ notes are keyed when a string touches a specific segment. An expression pedal is used to fade the organ sound in and out, while the guitar can be played at the same time.

Bob Murrell is credited with its invention and Musiconics International (MCI) of Waco, Texas claims to have introduced the Guitorgan. However, many others have created them starting with many models of the guitar. In any case, all have the basics in common: Convert a standard electric guitar into a Guitorgan through the addition of electronic organ components. The most critical part of making a Guitorgan is to separate each guitar fret into six segments, creating independent contact switches for each string. The organ notes are keyed when a string touches a specific segment, thus, making the ground connection necessary for the organ circuit to produce output. TTL logic circuitry determines the highest fret segment making contact on each string, and prevents simultaneous organ notes on the same string to activate; only the highest organ note played on a particular string will sound.

The organ section in a Guitorgan is a 6-note polyphonic circuit, which allows full guitar chords to be played. The guitar section always remains playable, but organ notes can be played alone or simultaneously with the guitar. The idea behind being a "Guitorganist" is to use the Guitorgan's expression pedal to creatively and accurately bring the organ in and out of the musical foreground while playing the guitar at the same time (and vice versa) as if there are actually two separate musicians playing.

Murrell worked on converting existing products from the late 1960s. In 1968, he had a significant run of instruments based on semi-hollow body guitars from Japan. The B-300 and M-340 are among the most common examples from this run. Also in existence are the M-300 and the B-35 models. The B-300 FSG (Frequency Synthesized Guitorgan) models, introduced in the early 70s along with the B-35, are based on a master oscillator circuit utilizing a special 12-note divider integrated circuit which is an improvement to the older 12 oscillator design, the advantage being that tuning the FSG organ circuit only requires adjustment of the master oscillator frequency rather than adjustment of each of the 12 oscillator frequencies on the older models. Note that FSG pedals cannot be used with non-FSG Guitorgans and vice versa, since the two versions run on a different DC voltage. The multi-pin cable that goes between an FSG pedal and an FSG Guitorgan was labeled with RED ends at MCI for a safety reminder. Bob continued to introduce upgrades to the Guitorgan design that included analog synthesizer interfaces and even MIDI in the mid-1980s.

...
Wikipedia