JPH02269391A - electronic music box - Google Patents

Abstract

PURPOSE:To obtain a volume adjusting circuit, for which electronic control is easy, by providing a charging circuit to a capacitor having cases that first and second transistors are conducted by receiving a rhythm signal and that the first transistor is conducted. CONSTITUTION:Equivalent resistance value is changed in a state that transistors T1 and T2 to charge a capacitor C by the rhythm signal are conducted. Then, charging quantity to the capacitor C is adjusted. In the case of a large tone, a rhythm signal 1 simultaneously goes into A1 and A2 and a reverberative waveform 2 is made. Then, a modulated waveform 4 goes into an amplifier circuit AMP. In the case of a small tone, a rhythm signal 1' is inputted only to the A1. Then, since the rhythm signal 1' is not inputted to the A2, only the transistor T1 is in the conductive state. Thus, it is not necessary to use comparatively expensive parts such as a variable resistor or switch, etc., and simultaneously, the volume adjusting circuit, for which mechanical operation is not required and the electronic control is easy, is obtained.

Description

[Detailed description of the invention] The present invention relates to a volume control mechanism for an electronic music box.

An object of the present invention is to provide a volume control mechanism that is inexpensive and easy to electronically control in an electronic music box that uses a lingering waveform based on an RC discharge curve.

2. Description of the Related Art With the recent progress in electronic technology, electronic devices that generate music, sounds, etc. by driving speakers using electronically synthesized signals are rapidly becoming popular.

The volume control mechanism of such electronic devices mainly has a structure that adjusts the amplification factor of the amplifier circuit, but in the case of electronic music boxes with simple sound quality, the mechanism shown in Figure 1 is also used. FIG. 2 is a timing chart for explaining the principle of operation.

The rhythm signal shown in FIG. 21 is input to FIG. 1A. Transistor T becomes conductive only when rhythm signal 1 is at H level, and charges capacitor C. The charge stored in the capacitor C is gradually discharged through the resistor R while the rhythm signal 1 is at the L level, and an IN waveform 2 is obtained with a time constant determined by RXC.

In FIG. 1B, a melody signal with a frequency determined by the pitch of the note as shown in FIG. , a modulation waveform shown at 4 in FIG. 2 appears at point P in FIG.

If this modulation waveform 4 is appropriately resistance-divided by a variable resistor VR and a divided waveform 5 is input into the amplifier circuit AMP and the speaker SP is driven, the division ratio of the variable resistor VR is changed, so that the volume can be adjusted.

The disadvantages of this type of volume control mechanism are that it uses a variable resistor, which is a relatively expensive component that costs about 100 yen, and that it is necessary for automatic volume adjustment according to ambient noise, and for alarm clocks that gradually increase in volume. There are some things that are not suitable for fully electronic volume adjustment.

The present invention eliminates these drawbacks, and as shown in Figure 3, by changing the pulse width of the rhythm signal, the capacitor C
Fig. 4 shows a circuit diagram of a method for adjusting the volume by changing the amount of charge in the battery, and shows the signal waveforms of each part when the volume is high and low.

Since the variable resistor VR that was in Figure 1 is gone, P
The potential at the point becomes an input signal to the amplifier circuit AMP as it is.

Therefore, if 1 to 4 in FIG. 4 are created in the same way as 1 to 4 in FIG. 2, the maximum volume sound of the first (!I) will be produced.

Here, if the pulse width of the rhythm signal is made small as shown in FIG. 4, the capacitor C is only charged halfway, so a reverberation waveform 7 with a low wave height is obtained, and therefore a modulation waveform 8 with a low wave height is applied to the amplifier circuit. This will be communicated to AMP,
The volume becomes lower.

FIG. 5 is a circuit diagram of another implementation method of the present invention, in which the amount of charge to capacitor C is adjusted by changing the equivalent resistance value when the transistor that charges capacitor C is in a conductive state using a rhythm signal. shows.

In the case of a loud sound, the all-th rhythm signal 1 enters A1 and A2 in FIG. 5 simultaneously to create a reverberation waveform 2, and a modulation waveform 4 enters the amplifier circuit AMP.

Rhythm signal 1' for a small sound has the same pulse width as rhythm signal 1 for a loud sound, but is input only to A1,
2 is not input, so only transistor T+ becomes conductive.

In this case, since the isometric resistance is higher than when T1 and T2 are in a conductive state in parallel, a reverberation waveform 9 with a low fall width is obtained with the same pulse width, and therefore a small sound is generated.

By the way, the pulse width of the rhythm signal may be reduced as shown in FIG. 4, or the rhythm signal with the same pulse width may be
! Control of inputting input to At and A2 of I at the same time or inputting only to A1 can be realized by combining known techniques without using variable resistors or switches that require mechanical operation. be.

Therefore, the present invention eliminates the need to use relatively expensive components such as variable resistors and switches, and at the same time provides a volume control mechanism that does not require mechanical operations and is easily electronically controlled.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional electronic music box that forms a lingering waveform, modulates a melody signal, adjusts and amplifies the volume, and emits sound from a speaker. FIG. 2 is a timing chart for explaining the operation of the circuit shown in FIG. FIG. 3 is an example of a circuit diagram when the same portion as in FIG. 1 is improved according to the present invention, and FIG. 5 is another example. Figure 3 shows a method of changing the amount of charge of capacitor C by changing the pulse width of the rhythm signal, and Figure 5 shows a method of changing the amount of discharge of capacitor C by changing the equivalent resistance when the transistor is in a conductive state. be. 4 and 6 are timing charts for explaining the operation of the circuits shown in FIGS. 3 and 5, respectively. Figure 2 Figure 3] -1 ■■ layer [W- 5--vjita f-]]-11; Fig. 3 1] Mlt;-71-2----1■Tomo n-1]--
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Claims (1)

[Claims] It is equipped with a speaker as an electric signal/audio conversion means, and generates a melody frequency signal and rhythm pulse according to the electronically stored musical score, and the rhythm pulse creates a lingering waveform by instantaneously charging a capacitor in an RC discharge circuit. ,
In an electronic music box having a mechanism for producing a performance signal by modulating the melody frequency signal with the reverberation waveform, amplifying the performance signal and using it as a speaker drive signal to drive a speaker to perform music, the RC by the rhythm pulse is An electronic music box characterized by having a mechanism for adjusting the volume by adjusting the wave height of the lingering waveform by changing the amount of charge to the capacitor of the discharge circuit.