| 摘要 |
A power supply circuit in the tap device includes a first power supply circuit for generating a first power voltage of DC 24V to drive output switching relays, and a second power supply circuit for generating a second power voltage of DC 5V to be supplied to a receiving circuit and a microcomputer. The second power supply circuit lowers the voltage of the alternating-current power signal from the transmission line with a transformer, rectifies and smoothes the power signal with the lowered voltage, then generates the power voltage using a three-terminal regulator. The tap device can be used in CATV systems with different voltages of the alternating-current power signal employed, a power loss generated in the system with a high voltage is reduced, and the power consumption of the tap device can be suppressed.
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