JPH026661Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a constant output device in an amplifier circuit.

Generally, in an amplifier circuit in which the degree of amplification is controlled by the volume, the amplification output level naturally fluctuates when the volume is moved.

By the way, in recent years, for example, car stereos have come equipped with a so-called karaoke function, and some of them, as shown in Figure 1, allow you to enjoy karaoke by mixing your singing voice with the sound of a karaoke tape being played in the car, while also modulating the singing voice. Some devices are now able to be modulated and transmitted by a device. In FIG. 1, 1 is a microphone, 2 is a microphone amplifier whose amplification level is controlled by a microphone volume 3, and 4 is a clock generator 5.
A BBD that is driven according to the clock from and echoes the output audio (singing voice) of microphone amplifier 2.
(analog signal delay element), 6 is an echo volume that controls the feedback amount of the echo loop, 7 is a low-pass filter that removes the clock for driving BBD 4, etc. from the signal flowing through the echo loop, 8 is a tape playback head, and 9 is a preamplifier. , 10 is the main amplifier, 11
is a speaker.

However, in this type of car stereo, when the microphone volume 3 is moved to mix with the tape playback sound, the amplified output level changes, and the modulation level of the modulator changes accordingly. For example, when switching from receiving radio waves to receiving the singing voice, it is inconvenient to have to adjust the volume, and when the modulation becomes shallow, the S/N ratio worsens, making it difficult to hear.

This invention eliminates the drawbacks of the above-mentioned conventional ones and provides a constant output device for an amplifier circuit that allows a constant output to be always obtained in addition to the amplified output even if the volume controlling the amplification degree of the amplifier circuit is changed. The purpose is to

This invention will be explained with reference to embodiments shown in the drawings.

FIG. 2 shows an embodiment of this invention, in which 12 is a modulation volume branched from the amplified output of the microphone amplifier 2 adjusted by a modulation volume 3 and located before the modulator; The volume 12 is linked to the microphone volume 3 and has a characteristic opposite to that of the microphone volume 3. Figure 3 shows the main parts of Figure 2 in detail, and the microphone amplifier 2 is
Consists of OP amplifier, microphone volume 3 is OP
The degree of amplification is controlled by changing the feedback amount of the amplifier 2. Furthermore, the microphone volume 3 and the modulation volume 12 are two volumes having the same curve, and by reversing the connection, they have opposite characteristics. Therefore, the output of the modulation volume 12 becomes flat as the characteristic curve of the microphone volume 3 and the characteristic curve of the modulation volume 12 cancel each other out, as shown in FIG. The output level V ₀ is determined by the value of resistor 13 in FIG. Other parts in FIGS. 2 and 3 that are similar to those in FIG. 1 are designated by the same reference numerals.

The above device can mix the karaoke tape playback sound from the tape playback head 8 with the singing voice from the microphone 1 and output it from the speaker 11. At this time, the microphone volume 3 is moved to adjust the amplification level of the microphone amplifier 2. This can be adjusted arbitrarily. Moreover, when the microphone volume 3 is moved, the modulation volume 12 with the opposite characteristic is also moved in conjunction with it, and the output level of the modulation volume 12 is always maintained at V ₀ regardless of the position of the microphone volume 3. The modulation level of the modulator will always be kept constant.

In the above embodiment, an echo circuit using BBD4 is provided, but this may be omitted, and the constant output can be used not only as the input of the modulator but also for other purposes as appropriate.Furthermore, it is equipped with a karaoke function. It goes without saying that this invention can be applied to applications other than car stereos, and that various changes and modifications of the above embodiments are possible.

This idea is configured as described above, so even if you change the volume that controls the amplification degree of the amplifier circuit,
In addition to the amplified output, a constant output can always be obtained. Therefore, for example, when the content of the amplified output is modulated by a modulator and transmitted, if this constant output is used as the input of the modulator, the modulation level can be kept constant. For example, when applied to car stereos, it is now possible to enjoy karaoke by mixing the singing voice with the playback sound of a karaoke tape, while also modulating the singing voice with a modulator and transmitting it. This has excellent effects, such as allowing the receiving side to listen to the singing voice with a good S/N ratio without having to adjust the volume when switching from receiving radio waves to receiving the singing voice. .

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an example of a conventional one.
Figure 2 is a block diagram showing an embodiment of this invention.
FIG. 3 is a circuit diagram showing the main parts of FIG. 2, and FIG. 4 is a graph showing the characteristics of each part of those shown in FIGS. 1: Microphone, 2: Microphone amplifier, 3: Microphone volume, 4: BBD (analog signal delay element), 5: Clock generator, 6: Echo volume, 7: Low-pass filter, 8: Tape playback head, 9: Preamplifier, 10: Main amplifier, 1
1: Speaker, 12: Modulation volume, 13: Resistor.

Claims (1)

[Claims for Utility Model Registration] A first direction comprising: an amplification means; a volume located downstream of the amplification means for adjusting the degree of amplification; and a first direction in which the amplification output obtained from the amplification output is desired to be adjusted by the volume; branching a constant output into a desired second direction without adjusting the volume, and providing in the second direction an inverse characteristic volume having a characteristic curve that is the same in shape and opposite to the characteristic curve of the volume; A constant output device for an amplifier circuit, characterized in that the output level in the second direction is made constant regardless of adjustment of the volume by linking this inverse characteristic volume with the volume.