| 摘要 |
PURPOSE:To attain the low voltage operation and to set an oscillating frequency with high accuracy and simple constitution, by eliminating an AC voltage dynamic range at an input section of an astable multivibrator and bringing a power supply voltage of an FM modulator to a low voltage. CONSTITUTION:A circuit surrounded with broken lines 9 is a bias circuit giving a base voltage of a PNP transistor(TR) 37 and a voltage of the emitter of the TR37, i.e., a voltage of an IC external terminal 58 is eliminated for the temperature characteristic by selecting suitably the value of resistors 50-53. Further, a circuit surrounded with broken lines 8 is a bias circuit giving a base voltage of an NPNTR38 and a voltage of the emitter of the TR38, i.e., the voltage of the IC external terminal 60 is eliminated for the temperature characteristic by selecting suitably the values of resistors 45-48. An oscillating frequency corresponding to a DC level at the tip of synchronizing part and 100% white level is adjusted with an externally mounted resistor 56, and the DC level at the tip of the synchronizing part is adjusted to a prescribed oscillating frequency with externally mounted resistors 55, 57. |
