designing an octave up...

[Narcosynthesis]

right, i was wandering how this circuit would work out (if at all)

the waay i see it is the frequency of the signal will be doubled, so the note you put in will be outputted at a higher frequency...

right, here is the plan, start with a buffer, preferably with a volume control added, then afterwards, use a rectifier to turn the variable ac signal to an all positive signal, hopefully doubling the frequency, then repeat this with a second rectifier to make an all negative signal, then mix the two back together for the output
the volume control is there as the rectifier will cut the volume down slightly, so you can set it louder before hitting the rectifier so it is equal to the normal signal

would this plan work at all?

David

[brett]

then repeat this with a second rectifier to make an all negative signal, then mix the two back together

If you add a signal to its inverse, they cancel.
The ear will pick up either the positive or negative signal as an octave up.  The quality is ok, even though a sine wave becomes a a series of camel's humps.
What I've thought would make a fine octave would be a re-design of the RM octavia, but replacing the distortion/input section with something milder, like a TS9 or an NPN Rangemaster.

have fun

[freebird1127]

Agreed, just rectify the positive or negative signal to double the frequency, then send it through a cap to take off the DC voltage offset... maybe a simple op-amp volume control afterwards to allow amplification to make up for the lost signal.  This probably wont sound 100% clean though... to make it truly clean you have to phase shift the positive or negative rectified signal before mixing it back to the original, 90 degrees, I think.  I'm not sure how, maybe someone can expand on this?

EDIT:  sorry, not mixing it back to the original... before mixing it with the signal of the other polarity.  You know what I mean, it was your idea...  

[Jason Stout]

What I've thought would make a fine octave would be a re-design of the RM octavia, but replacing the distortion/input section with something milder, like a TS9 or an NPN Rangemaster.

similar idea, (I wonder how it sounds?):
http://www.geofex.com/Article_Folders/Screamer%20Octave/tsoctave.htm

[12afael]

I think is posible to get a good octabe up with a modulator/demodulator chip
on some schematic you can find a frecuence doubler and his responce is like 100khz I think it should work well and clean .
I try the mos doubler of R.G. without luck.