This is the receiver for the previous circuit found in the November 1991 Radio Electronics magazine. The frequency is 2.2 MHz determined by the coils.
This circuit from an old documentation uses an optocoupler to control the feedback. FET is...
We found this circuit in a publication for radio amateurs in 1974. The bipolar transistors can be...
This circuit was found in a documentation for radio amateurs from the 70s. The integrated circuits...