We found this circuit in a 1965 Electronic Design. Transistors are still common but admit equivalents for some of them. The circuit drains a current of only 4 mA.
Found in old American documentation, this circuit can be implemented with modern operational...
Found in an Electronics Now from the 90s, this circuit can be triggered by an external control...
This voltage controlled oscillator uses a varicap to change the frequency. Usin a 100 turns coil...