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.
The circuit shown is from the Texas Instruments optoelectronics manual, applying to low power...
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...
This filter that rejects a frequency range determined by the double-T was found in the August 1993...