This circuit is from a 1967 publication. The configuration holds true for modern transistors having a feedback across R2.
This adjustable source was found in a 1979 documentation, but all components are still common...
Frequencies from 1 to 10 MHz can be obtained with a small adjustment of the variable in a narrow...
This circuit, obtained from the Texas Instruments component datasheet, can control up to 25 mA of...