This circuit was found in documentation for radio amateurs of the 1980s. This is the so-called roger-beep, which is the beep that is transmitted when the talk-listen function is changed.
Found in RCA documentation two years 70, this circuit triggers an incandescent lamp at dusk. The...
Found in Popular Electronics from the 90s, this circuit is based on a PLL567 and employs high-end or...
This circuit was obtained in an English publication of 1977. The operational is of the type with...