JPS6282725A - Display device for electronic muting low frequency amplifier - Google Patents

Abstract

PURPOSE:To obtain a display device displaying the OFF-state of muting by detecting a voltage across a capacitor deciding the muting time. CONSTITUTION:When a power switch 2 is closed at first, an LED 4 for power indication is lighted, a constant current circuit 12 starts it operation at the same time and a capacitor 13 is biased negatively. In such a case, when the voltage across the capacitor is small, since a negative voltage at a voltage dividing point of resistors 5, 6 is sufficiently small, a transistor (TR) 11 is turned on and then a TR 10 is turned off. Thus, an LED 9 for muting-off indication remains turned off. When the charging of the capacitor 13 is progressed and the voltage reaches a voltage turning off the muting, while the resistance of the resistors 5, 6 is set so that the negative voltage at the voltage dividing point of the resistors 5, 6 reaches the pinch-off voltage of the TR 11, the TR 11 is turned off, the TR 10 is turned on and the LED 9 for muting-off indication is lighted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a display device for an electronic muting low frequency amplifier.

2. Description of the Related Art Conventional low frequency amplifiers are equipped with a light emitting diode (hereinafter referred to as 1NCD) that lights up to indicate power when the power is turned on.

The display circuit of the above-mentioned low frequency amplifier will be described below with reference to the drawings.

FIG. 2 shows a conventional display circuit.

In FIG. 2, 1 is a DC power supply with a power supply voltage v0°, 2 is a power switch, 3 is a resistor, and 4 is an LXD indicating the power supply.

The display circuit of a conventional low frequency amplifier is configured as shown in Figure 82, so when the power switch 2 is closed, the power display goes to L.
ED lights up.

Problems to be Solved by the Invention However, with the above configuration, when the power switch is closed, the power display LED only lights up, and there is no function to display that muting has been completed, so it is difficult to know when muting You can't tell just by looking at it whether it was oyy or not.

Furthermore, since there is no speaker relay in the electronic muting low-frequency amplifier, there is no sound when the relay contacts contact each other, so unless the low-frequency amplifier generates an output and the sound is emitted from the speaker, the muting will be 0FFI.
I can't confirm that it is.

Also, if electronic muting is applied externally to the low frequency amplifier, it is relatively easy to set the muting to 0FFI.
It is possible to add a function to display information, but in recent years, as low-frequency amplification circuits have become increasingly integrated into ICs, there is a strong tendency for peripheral circuits to be integrated into the same IC as the low-frequency amplification circuits. There are also cases where it is not possible to easily add a function to display muting OFF because there is no muting terminal.

In order to solve the above problems, the present invention detects the voltage of a capacitor that determines the muting time in a low frequency amplifier for electronic muting, and turns muting off.
The present invention provides a display device that displays what has been done.

Means for Solving the Problems The present invention includes an LED that displays Mugue 4hufu 0hufu, a voltage detection circuit that detects the voltage of a capacitor that determines the muting time, and a voltage detection circuit that detects the voltage of a capacitor that determines the muting time. It is composed of a LIED lighting circuit that lights up the llCD on the display.

Effect of the present invention With the above-described configuration, when the power switch is closed, the capacitor that determines the muting time is charged, and when a certain voltage is reached, the muting is turned off.
This characteristic is utilized to detect the voltage of this capacitor and light up the llCD indicating muting OFF.

Embodiment Hereinafter, a display device for an electronic muting low frequency amplifier according to an embodiment of the present invention will be described with reference to the drawings.

In Figure 1 B, 1 is a DC power supply, 2 is a power switch,
4 is IID for power supply display, 9 is LICD for Mugue 4fufu 0fufu display, 11 is a voltage detection transistor, 1o is a transistor that lights up LICD9 with muting OFF, 3,5°6.7,8 is a resistor, 13 is the capacitor that determines the muting time, 12 is the power switch 2
This is a constant current circuit that starts operating when the cap is closed.

In FIG. 1a, first, when the power switch 2 is closed, the power indicator LICD 4 lights up, and at the same time, the constant current circuit 12 begins to operate and the capacitor 13 begins to be negatively biased. At this time, when the voltage of the capacitor 13 is small, the negative voltage at the voltage dividing point of the resistors 6 and 60 is sufficiently small, so the transistor 11 (FICT in the case of Fig. 1 a) is ON, so the transistor 1o is OFF. are doing. For this reason, the LED 9 displaying MUGE 4fufu0fufu remains off.

Next, when the charging of the capacitor 13 progresses and this voltage reaches the voltage that turns muting off, the resistors 6 and 6 are connected so that the negative voltage at the voltage dividing point of the resistors 5 and 6 becomes the pinch-off voltage of the transistor 11. When the resistance value is set, the transistor 11 is turned OFF, the transistor 10 is turned ON, and the LED 9 indicating MUGE 4 FF 0 FF lights up.

In FIG. 1A, the transistor 11 is FIT.
However, the transistor 11 is a pnp transistor and is connected to the transistor 10 in a Darlington connection.

In FIG. 1, when the power switch 2 is closed, the power indicator LICD 4 lights up and charging of the capacitor 13 starts, but when the negative voltage of the capacitor 13 is small, the transistor 11 . Since 10 is OFF, 14D in the Mugue 4 Fufu 0 Fufu display remains blank.

Next, the voltage of capacitor 13 turns off the muting.
When the voltage for FF is reached, the voltage across the resistors 6 and 6 becomes the forward voltage between the base and emitter of the transistor 10.11 -2v.
If you set the resistance values of resistors 6 and 6 so that □,
Transistor 11゜1o is ONI,, Muguet 4fufu0
Fufu display (7) LED9 lights up.

Effects of the Invention As described above, the present invention has the following advantages:
lCD, a voltage detection circuit that detects the voltage of the capacitor that determines the muting time, and an I that lights up the LICII display of Mugue 4fufu0fufu when the voltage is detected.
XI) Since it is composed of a lighting circuit, when the electronic muting of the low frequency amplifier is turned off, it is possible to relatively easily light up the LED displaying the MUGE 4 FF 0 FF display.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a display device of an electronic muting low frequency amplifier according to an embodiment of the present invention, FIG. It uses a pnp transistor. FIG. 2 is a circuit diagram of a conventional display device. 1...DC power supply, 2...Power switch, 3,5゜6, 8-...-Resistance, 4,9-----
・-LED, 10.11...Transistor, 1
2... Constant current circuit, 13... Capacitor. Name of agent: Patent attorney Toshio Nakao and 1 other person/-
--Naomaru house O, 2-m-house 7, ya, switch 3667δ---(Mr. vshiaf!r 1 Fig. 4.9-LEI) ノθ -LEDF Fig. Kunnsuku//-<5 sword-
Cedar (Etrunk 12- constant voltage;, !pl!l path 4, IJ--Funna"ampu Fig. 2/--Inchimaru t, ;i 2--- also source input i, +, 3- A-4---LH[)

Claims (1)

[Claims] An electronic muting low frequency amplifier comprising a capacitor for determining muting time, a light emitting diode, a detection means for detecting the voltage of the electronic capacitor, and a lighting means for lighting the light emitting diode by detecting the voltage of the detection means. Display device.