This circuit was found in an American documentation from the 90's. The transistor is a general purpose one. The circuit oscillates well between 12 and 30 MHz with the indicated components.
This useful power supply was found in an 1985 Italian publication, but can still be assembled...
This dimmer for 12 V incandescent lamps was found in a 1966 General Electric documentation. The circuit has...
With this circuit any number of 4017 integrated circuits can be connected in series. The circuit is...