KIA6924S 데이터 시트보기 (PDF) - KEC

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KIA6924S

BIPOLAR LINEAR INTEGRATED CIRCUIT

KEC 

KIA6924S

In case of an FM preset tuner as shown in Fig.9, station

selection form F1 to F2 by the preset station selector switch

provides a drastic variation to the voltage applied to variable

capacitance diode.

Accordingly, all of the detector DC voltage variation traced

in and out the FM S curve and noise between stations as

shown in Fig. 10 come out as buzz sound.

F1

F2

Station

In case of the above FM preset tuner equipped with a

non-shorting type switch for station selection and the

station indicator LED (or an indicator lamp), only LED

voltage detection can operate muting securely by using

the terminal of KIA6924S, that is, the trigger A, as shown

by the dotted line in Fig.9.

For example, in case of presetting from F1 to F2, after SW of F1

turned OFF, SW of F2 becomes ON; therefore, detection of

switch OFF of F1 permits the muting operation to be performed.

All are turned to "buzz" sound

Fig. 10 "Buzz" Sound in

Present Type

Even in case of using a shorting type switch, if the contact of indicator SW linked with the preset SW is securely ON

several milli second ahead, the muting operation can be performed by voltage variation originated at LED ON.

If the shorting type switch cannot securely make the other switch ON, the muting starts operating by detecting the voltage

variation of variable capacitance by applying the terminal 3 of KIA6924S, the trigger B, as shown by the solid line in Fig. 9.

However, in case where F1 and F2 are the same station or close stations at reception each other, no muting can be operated.

(Variation is within several mV of variable capacitance diode voltage.)

1994. 11. 11

Revision No : 0

10/10

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