the author writes: Radio Shack Special…the name was given to it because all of the components may be purchased at your local or nearby hardware and Radio Shack store. Although Radio Shack does not carry a typical 6 lead AM/FM variable (tuning) capacitor for tuning in to all the FM stations, I have managed to come up with a simple little way of going from station to station by just stretching and sqeezing the DRAIN coil with some sort of non-metallic small stick; such as a tapered-wooden match-stick.
If you would prefer to use a variable (tuning) capacitor, you can always find these devices from any AM/FM tunable (not digital) radio or check to see if your local Wal-Mart carries a small blue portable AM/FM radio by ‘Lenoxx Sound’, which sells for around five dollars. From that radio, you can the salvage the variable (tuning) capacitor (with the plastic knob included), the headphones (in which I use for the Radio Shack Special) and the audio jack (also what I use for the project). A good buy for $5. The finished PCB in this project is adapted to either use a variable capacitor or not.
One transistor super-regenerative FM receiver: [Link]