| 摘要 |
PURPOSE:To decrease the number of output terminals and to simplify the control system, by enabling to turn on-off the subcarrier generating circuit in the multiplex circuit with the ternary level signal externally. CONSTITUTION:If the strength of electric field is lowered while FM stereo broadcast is in reception, the control signal of middle level is applied to the control signal input terminal A. Thus, the monaural control circuit 9 is operated to stop the operation of the multiplex citcuit. In this case, the transistor Q11 remains off because of the presence of the Zener diode Z1. At AM reception, if the control signal of high level is applied to the terminal A, the transistor Q11 turns on and ground potential is applied to the voltage controlled oscillation circuit and the oscillation operation is stopped. |
