JPS584357B2 - Tremolo Henchyousouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tremolo modulation device that is improved so as to generate a sustained modulated wave whose waveform is always at its maximum amplitude the moment the switch is turned on.

Electronic musical instruments such as electronic organs are equipped with various effect circuits to vary their performance, one of which is a tremolo modulation device that generates a mandolin effect.

This tremolo modulation device generates a signal such as a mandolin sound effect by guiding a signal generated by an oscillation circuit to an amplitude modulation circuit and modulating a musical tone signal.

The oscillation circuit of this tremolo modulation device is constructed as a relaxation oscillator using unijunction transistors, as shown in FIG. 1a.

That is, the unijunction transistor 1 becomes conductive depending on the charged value of the capacitor 2, and this conduction causes the capacitor 2 to be discharged, and this operation is repeated to generate a sawtooth wave from the output terminal 0.

A sawtooth wave A as shown in FIG. 1B is guided to an amplitude modulation circuit (not shown) and modulates a musical tone signal to form a tremolo (mandolin) signal B.

By the way, when amplitude modulation is performed using this oscillator circuit, the moment the switch is turned on, the effect does not necessarily correspond to the rise of the sawtooth wave, but begins in the middle of the rise of the sawtooth wave A, as shown in Figure 1b. It is likely that noise will be generated.

In this case, the modulated signal B will also be formed in the middle of one cycle, which has the disadvantage that the rise will be unclear at the moment the switch is turned on, resulting in an unnatural sound.

The present invention eliminates the above-mentioned drawbacks and provides a tremolo modulation device that always generates a modulation signal from the maximum amplitude of the waveform at the moment the switch is turned on, and can generate a clear sound effect.

That is, the tremolo modulation device according to the present invention includes a relaxation oscillator that repeatedly generates a signal at a constant cycle, an amplitude modulation circuit that guides the output signal of the relaxation oscillator as a modulation signal and amplitude-modulates a musical tone signal, and a tremolo modulation circuit that modulates the amplitude of a musical tone signal. It is characterized by comprising means for maintaining the operating state and applying a constant pulse at the same time as the key is pressed, and applying this pulse to start the oscillation operation so that the output is always applied to the amplitude modulation circuit from the time of the maximum amplitude of the waveform. It is something.

An embodiment of the present invention will be described below with reference to the drawings.

First, the oscillation circuit will be explained. As shown in FIG. 2a, the input terminal 11 is connected to the base of an npn transistor 13 via a resistor 12, and the base of this transistor 13 is connected to the ground terminal E via a resistor 14, and the emitter is connected directly to the ground terminal E. Connected.

Further, the collector of the transistor 13 is connected to the first base of the unijunction transistor 15, and the second base of the unijunction transistor 15 is connected to the resistor 1.
The terminals 6 and 17 are connected to a DC power supply (10) and a ground terminal E, respectively.

Further, the emitter of the unijunction transistor 15 is connected to the output terminal 18, and is also connected to the ground terminal E via a capacitor 19, and to a DC power source (10) via a resistor 20 and a variable resistor 21 in series.

In the above configuration, the bias is set so that the transistor 13 is normally in a non-conducting state (standby state), and when a key is pressed, a voltage signal B as shown in FIG. 2b is applied to the input terminal 11. It becomes electrically conductive.

That is, while this signal B is being applied, it continues to be in a conductive state, and due to the conduction of this transistor 13, a voltage is also applied to the first paste of the unijunction transistor 15, and the charging voltage of the capacitor 19 causes the unijunction to become conductive. Transistor 15 becomes conductive.

Due to this conduction, the capacitor 19 is discharged, and therefore the unijunction transistor 15 becomes non-conductive, and the capacitor 19 is charged again via the resistor 20 and the variable resistor 21, and when a predetermined potential is reached, the unijunction transistor 15 becomes conductive again. This operation of conducting and non-conducting is repeated to cause oscillation, and a sawtooth wave A is generated at the output terminal 18 as shown in FIG. 2b.

This sawtooth wave A is guided to an amplitude modulation circuit, which will be described later, and is used as a modulation signal for modulating a musical tone signal.

Since this oscillation circuit applies a pulse to the input terminal 11 at the same time as the key is pressed, a sawtooth pattern always occurs from the beginning of the rise.

That is, since the unijunction transistor 15 starts oscillating at the same time as the pulse is applied to the input terminal 11, the output sawtooth wave always rises from the initial point, and normal tremolo modulation is performed from the moment the key is pressed. .

Next, a tremolo modulation device using the oscillation circuit shown in FIG. 2 will be explained with reference to FIG.

In other words, in an electronic musical instrument, musical tone signals from a sound source 31 are selected by key switches on a keyboard 32 and sent to a filter circuit 33.
It is guided here and formed into various tones.

The output of this filter circuit 33 is led to an amplitude modulation circuit 35 via a tone volume 34, where it is modulated by a modulated wave from an oscillator 36, amplified by an amplifier 37, and taken out from a speaker 38.

The oscillator 36 is shown in FIG. 2, and a switch 40 is provided between it and the amplitude modulation circuit 35.

This switch 40 is a switch for tremolo modulation,
Inject it as needed while playing an electronic musical instrument.

Then, as described above, when the key switch is turned on, a constant pulse is applied to the oscillator 36, and the oscillation action is started only by the application of this pulse, and a normal waveform is generated from the beginning and normal modulation is performed.

Obtaining a normal modulation waveform from the moment the key is pressed in this way makes the rise clear and eliminates unnaturalness, and is particularly effective in mandolin effects because they are played well from the beginning.

Furthermore, since the oscillation circuit of this tremolo modulation device is of the emergency oscillation type, oscillation stops when no keys are pressed (when not playing), and therefore the modulated wave from this oscillator is not generated in the performance standby state. There is no danger of it being pronounced incorrectly.

Further, since this oscillation circuit can be constructed without using a coil or the like, there is an advantage that the construction can be simplified.

In the embodiment, a relaxation oscillator using a unijunction transistor is used as an example, but other oscillators may be used.

As described above, according to the present invention, it is possible to provide a tremolo modulation device in which the modulation waveform is always generated from the maximum amplitude when the key is inserted, and a normal tremolo modulation sound can be obtained from the beginning.

[Brief explanation of drawings]

Claims (1)

[Claims] 1 means for generating a pulse-like signal that rises at the same time as a key is pressed and continues in the key-pressed state; and an amplitude modulation circuit that guides the output signal of the relaxation oscillator as a modulation signal and modulates the amplitude of the musical tone signal. Features a tremolo modulation device.