HIGH PERFORMANCE TELEPHONE SET AVOIDING CALL HARD OF HEARING

摘要

PURPOSE:To eliminate the state of a call hard of hearing by providing an automatic level control circuit (ALC) to amplifier of a reception circuit section, and an automatic call sending control circuit to the amplifier of a transmission circuit section, using a special circuit for a coupling circuit and using a commercial power so as to assure a stabilized power supply with a DC low voltage and low current thereby attaining a high sensitivity telephone set. CONSTITUTION:An amplifier section is inserted to a reception circuit and an automatic level control circuit (ALC) is provided to correct a harmful influence due to the amplification. The transmission circuit is inserted with an amplifier section similarly and provided with an automatic call sending control circuit (APT) to correct the harmful influence. A variable resistor Rv is connected directly to the winding L2 of a transformer T2 in the coupling circuit to form the relation of Z0=Za easily, the transmission output is sent effectively and the side tone is minimized. The specific power supply of DC6V and 300mA current (current consumption of 40mA or below) being the result of rectification of a commercial power supply 100V is built in the power supply section so as to avoid any hindrance from the talking at a remote location from an exchange station.