| 摘要 |
PURPOSE:To reduce the cost and to miniaturize the titled circuit by composing the circuit of a pair of local oscillating circuits for receiving plural broadcast wave bands. CONSTITUTION:When a low wave (LW) broadcase wave band is received, a control signal with 0V is applied to a control terminal 7. A transistor (TR) Q1 is connected by the control signal and diodes D5, D6, D12, and D13 are also connected. On the other hand, TRQ2 is disconnected and diodes D1-D4, D10 and D11 are also disconnected. The LW band broadcase wave is sent to an LW tuning circuit through an antenna coil L5 for LW band broadcast wave. After 2 coils, a medium wave (MW) band secondary coil L3 and an LW band secondary coil L4, have been induced, the LW broadcase wave is supplied to a frequency mixer 12. When an MW broadcase wave band is received, a control signal with 0V is applied to a control terminal 6. The frequency mixer 12 can be used also for the MW band in common. |
