This circuit was found in the August 1972 issue of Radio Electronics magazine. The circuit generates 4 types of signals as can be seen in the diagram. The maximum frequency is around 20 kHz.
This circuit is from an English publication from 1976 but can be easily assembled with BC548...
This circuit consists of a relaxation oscillator with a neon lamp that triggers an SCR, generating high...
Found in English documentation, this touch sensitive switch must be powered by an isolation...