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.
This circuit is from a 1967 General Electric SCR manual. The capacitors are polyester and the...
This oscillator for frequencies up to a few tens of kilohertz was found in a 1970s documentation. The...
This varicap-less modulator circuit was found in an Electronic Design from the 90's. The circuit...