Here's a regenerative receiver I designed and built from scratch that tunes the 31-meter shortwave band (9 to 10 Mhz). The audio is "high-quality" because the circuit includes a pre-amp stage and an active, low-pass filter that produced audio levels sufficient to drive a speaker, but attenuates those annoying 5kHz "whistles" from stations in adjacent channels. The schematic can be downloaded from this page (scroll down).
A photo of the radio is shown below. At present, the circuit is sitting on breadboards. The tuning capacitor is at the left, the radio circuit (detector, amps and filter) is on the large breadboard at the center, and the power-supply is on the small breadboard near the top. Someday I'll transfer this creation to a circuit board and place it in a permanent enclosure. When the project's complete, I'll update this page.
