I can't see the atachments of this 2 articles (schematics and pics), but they look interesting:
http://www.elektor-labs.com/project/ota-overdrive-with-genuine-germanium-sound-130311-i.13401.html
http://www.elektor-labs.com/contribution/overdrive-update-08-2013.13459.html
I came accross them when looking info about OTA overdrives... I just heard Mike Hermans demo of the Moog MF Drive and it looks awesome....
I've been wanting to read that same article. :)