MC3335P use low-power narrowband FM receiver, you can design a very simple 80 m SSB receiver. MC3335 also has a comparator circuit
for FSK detection. The circuit is very simple and requires few external components, it includes a simple audio IC is based on an LM386 audio power amplifier. Since MC335P IC input voltage required 2 and 6 volts and LM386 requires a 9-volt DC power supply, this circuit is used in the two fixed three-terminal regulator between. This receiving circuit is a variable capacitance diode or a variable capacitor circuit.