Local/dx switching circuit

Abstract

Abstract PURPOSE:To obtain an LOCAL/DX switching circuit of an on-vehicle receiver with comparatively simple structure by changing forcibly the mode into the LOCAL mode and restoring the mode into the DX mode at the end of operation in the automatic tuning or preset scanning at lighting of a lamp at night. CONSTITUTION:A potential divider comprising resistors R2 and R3 is connected between a terminal 5 reaching a lighting circuit and ground and a connecting point between the resistors R2 and R3 is connected to a base of a transistor (TR)Q5. Then they are selected to be R3>R2. When a voltage of >=12V is fed to the terminal 5 reaching the lighting circuit, a voltage of 5V from a controller turns on a TRQ4 via a resistor R4 and a Zener diode D2 and an RF signal is fed to a mixer circuit while being attenuated by nearly 20dB by a series circuit comprising a capacitor C1 and a resistor R1. When a station detection signal exists, the scanning is stopped to bring the station to be received.

Inventors

• 👤 Toshiyuki Imagawa
• 👤 今川　敏幸
• 👤 Hideo Inomata
• 👤 猪又　英夫
• 👤 Shigeo Akazawa
• 👤 赤沢　茂男

Bibliographic Details