Found in an April 1977 Radio Electronics issue, this circuit uses the well-known XR2206. The C1 values for the various frequency bands are given next to the diagram.
This circuit was obtained in an American documentation translated in the 80's. The circuit can be...
This electronic roulette circuit with 10 numbers was found in a Popular Electronics from the 80s....
Based on a CA3059 zero-cross switch, this circuit was found in the July 1995 Electronics Now...