CLOSING CIRCUIT OF LOW LOSS CIRCUIT

摘要

PURPOSE:To obtain a closing circuit of a low loss circuit by connecting a voltage source almost equal to the voltage between the base and emitter of a transistor (TR) circuit to be inserted into the paired trunk circuit of a private branch exchange in series to the base bias circuit of the TR circuit. CONSTITUTION:The closing circuit 7 of low loss circuit inserted into the line of the paired trunk circuit of the private branch exchange to close a DC loop is constituted by using a TR25. A diode 27 having forward voltage drop almost equal to the voltage between the base and emitter of the TR25 is connected in series to the base bias circuit of the TR25 as a voltage source. Even if line resistance is generally 1KOMEGA or less the closing circuit of the low loss circuit which can pass an about 1.5V AC signal having no distorsion is obtained.