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本人将HD868型脉冲式话机改成双音频话机,使用一年多,效果良好。被改制的话机是早期生产的半集成电路脉冲式话机,电路图见图1。它使用的脉冲拨号芯片是AY-9151B(IC9102E)。摘机时,外线电压一路稳压后经电阻R_103加到启动开关管Q_101的集电极;另一路经R_105和R_106给Q_101提供偏置电流,使管子饱和导通,使IC9102E的12脚输入为低电平,此时进行键盘拨号。挂机时,隔离二极管反向截止,管子无偏置电流而截止,12脚输入为高电平,键盘操作无效。1、5脚为电源正端V_DD,由稳压电源供给,R_104为限流电阻,C_102为电源滤波电容器。R_110、C_103、C_104为振荡回
I will HD868-type pulse phone into a dual-tone phone, using more than a year, the effect is good. The phone was modified is the early production of semi-integrated circuit pulse phone, the circuit shown in Figure 1. The pulse dialing chip it uses is AY-9151B (IC9102E). Off-hook, the external voltage regulator after all the way through the resistor R_103 added to the start of the collector switch Q_101; the other way through the R_105 and R_106 to provide bias current Q_101, so that the pipe saturated conduction, IC9102E 12-pin input is low Level, then dial the keyboard. On-hook, the isolation diode reverse cut-off, the tube no bias current and cut off, 12 feet high input, the keyboard operation is invalid. 1,5 feet for the positive power supply V_DD, by the regulated power supply, R_104 for the current limiting resistor, C_102 for the power supply filter capacitor. R_110, C_103, C_104 are oscillation back