| 摘要 |
PROBLEM TO BE SOLVED: To provide a telephone set circuit that can suppress an echo from a receiving wire in a curl code to a transmission wire to a level of a degree unable to be recognized in a listening sense with a very simple circuit configuration. SOLUTION: Attaching an approximate circuit having an impedance equivalent to a difference between coupling impedances from each wire of a receiving wire pair of the curl code to each wire of a transmission wire pair to between an inverting terminal and a noninverting terminal of a differential amplifier that amplifies an output of the curl code leading to a handset allows the transmission amount of the output to the inverting terminal and the noninverting terminal to be uniformizes so as to suppress an echo caused by crosstalk of the output from the receiving wires to the transmission wires by means of the differential amplifier.
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