So I've got this idea for an octaver...

[karolisd]

So I've got this idea of this ultra simple octave up and down pedal. My idea was to take the octave part of the Shocktave, put a booster in front, run the single transistor octave up (this one: http://www.diystompboxes.com/smfforum/index.php?topic=71134.40) in parallel and use a blend knob to mix the up and down octaves.
I guess it would look something like this:



Any comments or suggestions? Also, could it work?

[thehallofshields]

Nothing inherently wrong with the idea. Perhaps you could link or describe where the octave-up portion of the circuit is pulled from?

[Keppy]

It should work, but I do have some suggestions.

The 100k resistor connected to the mix pot will create a voltage divider that could throw off your mix. Also, there's a ton of boost, so you'll probably need a volume pot. You could solve both problems by removing that resistor and instead placing a volume pot off the wiper of the mix pot. For best results, the volume pot should be a much larger value than the mix pot.

I suspect you'll find a need for one or more buffers. Collector outputs tend to be relatively high impedance. Sometimes it's not a problem, but if it is then the passive mixer compounds the problem because it's also impedance sensitive. Additionally, the octave up circuit seems to rely on diode switching, so the output impedance of that section might vary during different points of the wave cycle, which could also affect the mixing. Or not. You might find it useable as is, or find you need buffers after each octave section and after the mix pot, or just some of those. None of these problems should keep it from working, but if it's not working as well as you'd like that's what I'd look at changing.

Looks cool! I hope you can get it working.

[antonis]

As Keppy mentioned:<there's a ton of boost>

I'd suggest emitter resistors for all transistors (i.e. 1k for Q1, 47k Q2, 10k for Q5 and "your taste" for Q3 & Q4..)

A variable resistor between Q1's collector and C2 should give you the possibility for a "clean" octave blend..