This circuit is from Motorola's Linear Interface ICs of 1993. The circuit can be powered by symmetrical 6 to 12 V voltages and for a stereo version, two channels must be built.
In this circuit found in the December 1972 Radio Electronics magazine. R can be from 1k to 22k,...
This circuit can operate between frequencies from 1 to 15 MHz depending on the coil. For 3.5 MHz...
This metal detector circuit uses an AM radio as an indicator. The radio is placed off-station and tuned...