This circuit with a differential pair was found in the August 1974 Radio Electronics magazine. The frequency is determined by L1 and the variable capacitor.
This circuit appears at various points in this section and on this site, with minor variations. It uses the...
This direct detection circuit was found in a 1986 documentation. The output is of low power, but...
Other amplifiers of the series like the MC3301, MC3401 and LM2900 can be used in this circuit. We found...