About the ROCTAVE DIVIDER - Vintage Analogue Octave Divider Circuit
|Guitar Effects and other books
by Craig Anderton
The whole point of Craig Anderton's original series of guitar oriented electronics articles was to demystify guitar effects and give guitarists (read: electronics novices) the ability to understand & build their own stomp boxes.
That said, it should be noted that most of Craig Anderton's books are rather expensive, particularly when the content has not been updated in decades. At a minimum Craig's books should be revised to include currently available replacement components and any related circuit and/or PCB layout adjustments.
Without these updates the usefulness of the books to an electronics novice is highly questionable.
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The Rocktave Divider (a vintage analogue octave divider circuit primarily for guitarists) by Craig Anderton was first published in the April 1983 edition of the Guitar Player magazine, with some follow-up mods released in the October 1983 edition.
The article provides a reasonably comprehensive description of the circuit functionality, includes a Circuit Schematic, PCB (Printed Circuit Board) design, PCB Parts Overlay Diagram and parts list. The parts should all still be available (or their current workable alternatives) and as a D.I.Y. project, parts are probably cheaper now than when the article was first published.
Overall I would rate this project as Moderate Difficulty due to some of the ICs (Integrated Circuits) requiring some care with respect to handling and insertion onto the circuit board (particularly the 4013 dual flip-flop - i.e. to avoid damage due to static discharge).
Due mostly to Craig Anderton's penchant for using the (no longer readily available) RC4136 Quad Op Amp (which at the time was unavailable in Australia and expensive if ordered from the US), I never built this circuit. Instead, I purchased the Boss Octaver CE-2, which is now (apparently) considered somewhat of a highly desirable classic.
So, not having built the Roctave Divider, I can only comment/evaluate the circuit based on the schematics.
The first thing that I would change in the Rocktave Divider circuit is to replace the 4136 Quad Op amp package with quieter Op Amps. Perhaps something like the NE5534 would do the job (four of these would be required). However, this would also mean a substantial redesign/revision of the PCB, so it may be more work than it's worth.
The RC4136 Quad Op amp uses an unusual pinout for its power connections where pin 11 is positive and pin 7 negative. Bear this in mind when looking for replacements.
Still, the two articles provide an interesting starting point. If you are into using a prototyping board, it shouldn't be too much work to come up with some interesting variations of this circuit based on these two articles.
Rocktave Divider by Craig Anderton Part 1 (PDF - 3.6MB)
Rocktave Divider by Craig Anderton Part 2 - Mods (PDF - 1.2MB)
Incept: Wizard - 130909
Last Updated: 130912