reccomend an octave up build

[Mark Hammer]

This is, in fact, precisely what the Aphex B unit did to generate harmonics.  The audio signal was high-pass filtered, then fed to both an OTA and an envelope follower with a very fast decay (so as to keep a fair amount of ripple in to reflect the frequency content).  The envelope follower then feeds the OTA control input to modulate it at the same frequency as the audio input.  Presto, chango!! All the input is frequency doubled, then mixed back with the original full-bandwidth audio signal.

[Gus]

this is a very simple build.

http://www.diystompboxes.com/pedals/SOU2.GIF

Use the transformer for the Tyco clones. 

Note the 1k, look at the tyco output drive  Z to the transformer.

Use any opamp you want use a dual just don't use the other half................................................

Increase the 100 ohm to 220, 470 etc for less drive/fuzz and finer gain control.

Have Fun