JPS6282825A - Display device for electronic nuting low frequency amplifier - Google Patents

Abstract

PURPOSE:To obtain a display device for displaying OFF of muting by detecting the voltage of a capacitor for determining a muting time, and lighting up an LED in a power supply more brightly at the OFF of the muting. CONSTITUTION:When a power supply switch 2 is closed, the capacitor 12 starts negative electrostatic charging. When the negative voltage is low, an FET 10 is turned on, a transistor (TR) 9 is turned off and current I4 flowing into an LED 4 becomes I4=Vcc/R3+R8, so that the LED 4 is lighted up. When the capacitor 12 is gradually charged and its voltage reaches a negative voltage for turning off muting, the FET 10 is turned off if the resistance values of resistors 5, 6 are set up so that the FET 10 is turned off. Since the TR 9 is turned on, a resistor 8 is shorted, current I4' flowing into the LED 4 becomes Vcc/R3. Since I4'>I4 is formed, the LED 4 is lighted up more brightly.

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.

BACKGROUND OF THE INVENTION Conventional low frequency amplifiers are equipped with a power display diode (hereinafter referred to as LED) that lights up 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 the power supply voltage V. C is a DC power supply, 2 is a power switch, 3 is a resistor, and 4 is a power supply display llCD.

The display circuit of a conventional low frequency amplifier is configured as shown in Figure 2, 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 fully closed, the power display (LKI) only lights up, and there is no function to indicate that muting is turned off.
You cannot tell when muting is turned off just by looking at it.

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 muting must be turned off unless the low-frequency amplifier generates the full output and no sound is emitted from the speaker. I can't confirm that it is.

1. If electronic muting is applied externally to the low frequency amplifier, it is relatively easy to add a function to display that muting has been turned off.
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 XC as the low frequency amplification circuits. There are also cases where it is not possible to attach it.

In order to solve the above-mentioned problems, the present invention detects the voltage of a capacitor that determines the muting time in a low frequency amplifier for electronic muting, and muting is stopped at 0FI.
The present invention provides a display device that displays that F has been performed.

Means for Solving the Problems The present invention utilizes a conventional power display LICD to detect a capacitor voltage that determines the muting time, and when the voltage is detected, a power display LED is activated. It is composed of an LED lighting circuit that changes the brightness (makes it brighter).

Operation The present invention uses the above-described structure to detect the voltage of this capacitor by utilizing the characteristic that when the power switch 2 is closed, the capacitor that determines the muting time is charged, and when a certain voltage is reached, the muting is turned off. Then, when muting is turned off, the power display turns to L.
It lights up brighter than the EDi to indicate 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 1a, 1 is a DC power supply, 2 is a power switch, 4
is an LE that serves as both a power display and a muting OFF display.
D, 10 is a voltage detection transistor, 9 is a transistor that lights LED 4 brightly, 3, 5, 6, 7.8 are resistors, 12 is a capacitor that determines the muting time, 1
1 is a constant current circuit that starts operating when the power switch 2 is closed.

First, in Figure a, when the power switch 2 is closed,
Capacitor 12 starts to be negatively charged, but when this negative voltage is small, transistor (in this case FET) 10
is ONL and transistor 9 is OFF, so LC
The current flowing through D4 is I, (A), the power supply N voltage t Mac
(V), and the resistance values of resistors 3 and 8 are R and (Ω), respectively.
, R8 (Ω), the current 14='t/CC/ (R3+R8) is L
The signal flows to CD4, and CD4 lights up.

Next, if the value of resistor 5.6 is set so that when the capacitor 12 is charged and reaches a negative voltage that turns muting 1 OFF, the transistor 10 turns OFF.
Transistor 10 is OFF and transistor 9 is ON
Therefore, the resistor 8 is short-circuited, and if the current flowing through LKD4 at this time is (A), then I = V, , /R3, and I,')I, so the LED lights up brighter than before.

In FIG. 1A, the transistor 10 is an FET.
However, the transistor 1o is a pnp transistor, the transistor 9 is a pnp transistor instead of an npn transistor, and the transistors 9 and 10i are connected in a Darlington manner.

In FIG. 1, when the power switch 2 is closed, the transistor 1o is 0Flj, and the transistor 9 is also OFF, as in the case of FIG.
, = -Vc, / (R3+R,') current flows and the LED 4 lights up.

Next, the negative voltage on capacitor 12 turns off the muting.
If the voltage at the voltage dividing point of resistor 5.6 is set to be 12vBx when the FF voltage is reached, transistors 9 and 1o will be ONL, and resistor 8 will be set to '/-i-'. l
A current of l'=-vac/Rs flows through lCD4,
At this time, "a'>" becomes a, so the LCD 4 lights up brighter than before.

Effects of the Invention As described above, the present invention changes the current flowing through the power indicator LED when muting is OFF.
Since it changes the brightness of D, one 1. )
Power display and meeting OFF display with ID? can do.

[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. pnp) Run sister portion was used. FIG. 2 is a circuit diagram of a conventional display device. 1...DC power supply, 2...Power switch, 3.5°8.7.8...Resistance, 4...
・LED, 9, 1o...Transistor, 11・
... Constant current circuit, 12 ... Capacitor. Name of agent Patent attorney Toshio Nakao and 1 other person No. JL-Maru 1 Tomen 2--Ichiyake no Ni Mata I Nochi 35 Otsu δ-ffi Hole 1 Figure 4-LE. 9 10-h Run'Sc/I -Hole: Full turn Rt/2--- F;Swamp Figure 2/-m= Straight,;Lt, Wood? -m= Inch 3- & 4-L Snap

Claims (1)

[Claims] An electronic muting device comprising a capacitor for determining a muting time, a light emitting diode, a detection means for detecting the voltage of the capacitor, and a lighting means for changing the current flowing through the light emitting diode by detecting the voltage of the detection means. Frequency amplifier display device.