| 摘要 |
PURPOSE:To achieve a frequency monitor in common use with display, by providing the 1st transistor (TR) which is turned on/off with the presence of a display signal and introduces a display driving output, and the 2nd TR which converts a frequency monitor signal into a switching current for output. CONSTITUTION:When an output of a lamp driving circuit is applied to the base of a TRQ11 in an IC circuit IC(PLL-MPX) for multiplex type demodulation using phase locked loop, a light emitting diode LED of a display circuit DC illuminates for the display of reception of stereo signals. On the other hand, in monitoring the output of a voltage controlled oscillator, the output of the lamp driving circuit is stopped, the output of a monitor signal source OSC is applied to TRs Q13, Q12 and the output at a terminal T11 is counted with a frequency counter FC of a monitor circuit FM. |
