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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing one example of a
conventional muting circuit, FIG. 2 is a circuit diagram of one embodiment of the muting circuit
of the present invention, and FIG. 3 is FIGS. It is a characteristic view of the distortion rate in the
circuit of 2 figures. Tr1 иии Emitter follower transistor, Tr2 ииииии Muting control transistor, D1, D2
ииииии Diode, R1 to R6 иииииииии Resistance и RL и и и ииииии Load resistance, C1 ииииииии Capacitor. Fig. 1 In 1-149-148001 (2) Fig. 2 Fig. 3
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a muting circuit
used in a multi-channel disc reproducing apparatus and the like, which can obtain the original
attenuation amount at the time of muting and improve the distortion on the output side at the
time of large input signals. It is an object of the present invention to provide an efficient muting
circuit. (1) First of all, the input signal applied to the terminal for prescribing seven examples of
this type of circuit in the prior art together with FIG. 7 is applied to the base of the buffer
transistor T71 which is emitter-follower connected. The output of this transistor T7 ? is taken
from both ends of the resistor R ? connected to the emitter, and is applied in the forward
direction to a series circuit of a silicon diode D and a resistor R2. Furthermore, the voltage across
the resistor R2 is supplied to the load resistor RL via the capacitor C2. On the other hand, the
transistors T and 2 are control transistors for performing a muting operation, and a control
signal is applied to their pace. The signal taken out by the collector resistor R5 is applied to the
point A via the resistors R, R. Now, when the transistor Tf2 is in the cut-off state, no voltage is
applied to the point A, so the diode D ? is turned on. Accordingly, the signal added to the input
terminal xnic is supplied to the load RL through the low resistance in the forward direction of the
diode D ? via the transistor T2 ?. Also, when the transistor T is turned on by the control signal,
the positive (2) potential of its collector is added to the point A via the resistor R4 * R3, and the
potential A at the point A is from the i position VB of the point B To turn off the diode Di.
Therefore, the resistance value of the diode D is increased to prevent the signal applied to the
input end from being supplied to the load RL. When driving another channel by the control
signal, the voltage at the connection point C of the line resistance R51: Ra is taken out-when the
collector potential of the transistor Tf2 is directly applied to the junction point, the transistor T,
When a fast rising and falling control signal is applied to the input, a capacitor noise is generated
by switching, so to prevent this, insert a capacitor C ? between the 0 point and the dark of the
earth to give an appropriate time constant. There is. Further, when the muting circuit is used for
a multi-channel demodulator, this capacitor 01 also has the function of giving an appropriate
holding time constant to carrier breakage in multi-channel disk in ? channel multi auto muting
operation tC. Furthermore, when driving the other multiple (5) number of muting circuits with
the switching voltage of the transistors T, ?, the capacitor C ? also has the function of
eliminating crosstalk between the channels.
Therefore, although this capacitor C1 is essential, when there is a point t't, the series circuit of
the resistor R3 and the capacitor C @ s also forms an AC load circuit with respect to the output at
the point A. For this reason, the human power signal is divided by the internal resistance of the
diode D ? and the above AC load, and the distortion on the output side ?a? is not less due to
non-linearity of D) when the input signal is large at ZV @ degree. There was a drawback that
made it worse. Father In the case of the above-mentioned connection, the amount of attenuation
of the input signal in the IC at the time of muting was also a small problem of about 45 dB. The
uninvention is a solution to the problem during the above. FIG. 2 is a circuit diagram of the
muting circuit which is not devised. The same reference numerals are given to the same
components as FIG. 1 and the description thereof is omitted. The circuit according to the present
invention is characterized in that a diode D2 is connected between the point h and the point 0
instead of the reverse bias resistor R5 conventionally connected to utilize a forward resistance.
According to the (?) configuration, when the transistor T is in the off state, the point C is at the
ground potential, so that the diode D2L is reverse biased. Therefore, since the diode D2 exhibits
extremely high resistance, the load for the output at the point A is only the capacitor C2 and the
14-load resistor RL, and the capacitor C1 is not involved in N operation. Therefore, the load
circuit can be made sufficiently high in comparison with the forward quotient resistance of the
diode D ?, and the distortion factor of the output is considerably improved. When the transistor
Tf2 is in the on state, a current flows in the diode D2 through the resistor R6 + R2, and the same
bias is obtained. The point A is grounded beyond the forward low resistance of the diode D2 and
the capacitor C ?. On the other hand, in this state, the diode D ? is reversely biased and exhibits
a high resistance at the same as i1 described above. Therefore, it appears at the emitter of the
transistor T, ? (# @ 1, divided by the high resistance by the diode D ? between the point B and
the point A and the low resistance VC between the point A and the ground, the point A
Attenuation voltage will be applied to the load RL, so how much is it attenuated? It is extremely
large (5) with OdB or more. Here, as the diode-)-D2, since it is required that the layer direction
resistance be smaller than the large reverse resistance, a germanium diode is particularly
suitable. FIG. 3 shows the result of measurement of the strain rate in the case of load resistance
RL force IJLQ or more by the circuit of FIG. 7 and FIG. 2, and curve ? in the case of FIG.
Transmit the characteristics. As is clear from the figure in the figure, according to the circuit of
the present invention, the distortion factor is 0. 0 even for an input signal as large as lv.
/-Can be reduced to the following. As described above, since the muting circuit according to the
present invention is configured to apply the output of the control layer transistor to the
controlled point via the diode, a part of the muting control J111 circuit becomes an AC load. In
addition to being able to prevent distortion, it is possible to prevent the enhancement of the
distortion factor, and it is possible to increase the attenuation of the input signal at the time of
muting by utilizing the low resistance in the layer direction of the diode.
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