I found this circuit in a documentation for radio amateurs from 1975. The FET could be the BF245. The circuit works in the range of 40, 80 and 160 meters of radio amateurs.
This CMOS logic-based circuit was found in the April 1974 issue of Radio Electronics magazine. The circuit...
This circuit is from an American publication from the 60's. The power is on the order of 600 mW....
Using a window comparator, this circuit trips over a certain range of input voltages. Formulas for...