I got to see the Rolling Stones a couple days ago and when they kicked into (I Can't Get No) Satisfaction as their second encore, I realized I hadn't laid out the effect responsible for one of the greatest songs of all time.
The FZ-1 used 2, AA batteries to run off 3v, and the FZ-1A used a single AA battery to run off 1.5v. The circuit was designed to be friendly with the wide range of hFE gains and leaky germanium transistors in production at the time. So when you're picking out transistors for Q2-3, either pick leaky high gain or low leakage and low gain (less than what you'd use in a Fuzz Face). Original units were positive ground effects with PNP transistors. I've laid the perfboard side out for positive ground and the PCB side for negative ground. I've also added some extra components to get supply voltage down from 9v to about 1.5v, so you can daisy chain it with other effects (if you're building the negative ground version).
This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.