fsk modulation and power line interface circuit diagram

The circuit modulates , amplifies , transmits and isolates high voltage serially encoded control signals . The 556 time base circuit and R1, R2, C1 and R3, R4, C2 form two astable multivibrators respectively, generating two signals, 100kHz and 90kHz. The serial control signal controls the analog switch CC4066. When the level is high, 556 pin 5 outputs 100kHz harmonics to the VT1 resonant amplifier and T, CX1, CX2 for isolation and coupling to the power line . T1 and C8 form a frequency selection circuit, and T, CX1 and CX2 form a high-voltage isolation circuit. When the serial signal is low level, 556 pin 9 outputs 90kHz harmonics to VT2, which is coupled to the power line through resonance amplification and T, CX1, and CX2 isolation. This circuit can utilize the power line carrier channel to transmit control signals .

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