This SCR relaxation oscillator was found in an 80's Electronic Design. It flashes a small incandescent lamp in frequency that depends on the capacitor.
This ohmmeter can be made with a scrap milliammeter used for continuity tests or even resistance...
This circuit was found in the November 1992 issue of Radio Electronics magazine. The circuit has...
Found in an English Maplin documentation from 1983, this circuit generates separate frequency...