This high-Q low-pass filter was found in the October 1990 issue of Radio Electronics magazine. The frequency depends on the capacitors used and is on the order of a few tens of hertz.
The Micro-Lock line of Molex connectors can be obtained from Mouser Electronics. These connectors...
This powerful amplifier with output in complementary symmetry is from an old documentation....
This circuit is from 1964 documentation but can be easily implemented based on current components....