JPH04131142U - power circuit - Google Patents

Abstract

(57) [Summary] [Purpose] Provide a circuit that connects and disconnects the power supply to the audio amplifier, prevents the generation of noise when the audio amplifier starts up, and also functions as a smoothing filter for the power supply circuit. . [Structure] By applying a power connection/disconnection signal 6 to the base of a control transistor 5 of a DC power supply smoothing circuit, the smoothing circuit is turned on and power is supplied to an audio amplifier 11 to operate the audio amplifier. A capacitor 8 is connected between the base of the transistor 5 of the smoothing circuit and the ground to remove ripples in the power supply. Resistor 7 is connected to the base of transistor 5 of the smoothing circuit.
A power connection/disconnection signal 6 is input through the circuit, a capacitor 8 is connected between the base of the transistor 5 and the ground, and by providing a time constant, the voltage is gradually increased after the audio amplifier 11 is turned on until it stabilizes. This prevents the noise generated from the loudspeaker amplifier.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a power supply circuit, and more particularly to a device for opening and closing the power supply circuit of an audio amplifier.

0002

[Conventional technology]

In recent years, personal computers have become popular, and monitors for personal computers have become commonplace. It started to get worse. If you try to watch TV broadcasts while using a computer, the TV reception will be interrupted. machine is required. Installing a TV receiver takes up a lot of space, so it is difficult to install a TV receiver. TV broadcasts on your computer monitor using a tuner unit with There has been an increase in the number of ways in which images can be used. Click here to operate the tuner unit with the remote control. Keep the primary power source of the tuner unit on at all times, and connect each function on the secondary side using the remote control. ・It has become necessary to perform a disconnection operation. For example, to amplify the audio signal from a tuner circuit. It has become necessary to connect and disconnect the operation of circuits that

0003

[Problem that the idea aims to solve]

This invention was devised in view of the problems of the conventional technology mentioned above. A circuit is provided to connect and disconnect the supply, and that circuit is used to prevent noise when the audio amplifier starts up. It prevents this from occurring and also functions as a smoothing filter for the power supply circuit.

0004

[Means to solve the problem]

In order to solve the above problems, the present invention has developed a power supply for the audio amplifier that amplifies the audio signal. In the circuit, one end of the first capacitor, one end of the first resistor and the first Connect the collector of the transistor, and connect the negative terminal of the power supply and the other end of the first capacitor. ground, the emitter of the first transistor is grounded via the third capacitor, and the sound Connect to the power terminal of the voice amplifier, and connect the audio signal input to the input terminal of the voice amplifier. At the same time, a speaker is connected to the output terminal, and a second transformer is connected to the other end of the first resistor. The collector of the transistor is connected, and the emitter of the second transistor is connected to the collector of the first transistor. When connected to the base and the base of the second transistor is grounded through the second capacitor, Both provide a power supply circuit configured to be connected to a power connection/disconnection input terminal via a second resistor. It is something.

[0005]

[Effect]

According to the above configuration, the power supply is connected to the base of the control transistor of the DC power supply smoothing circuit. ・By adding a disconnection signal, the smoothing circuit is turned on and power is supplied to the audio amplifier. Activate the audio amplifier. Connect a capacitor between the base of the smoothing circuit transistor and ground. Remove ripples from the power supply by connecting a sensor. Base of transistor in smoothing circuit Input the power supply connection/disconnection signal through the resistor and connect the capacitor between the base of the transistor and the ground. By connecting a capacitor and providing a time constant, the audio amplifier can be turned on and stabilized. to gradually increase the voltage to prevent noise generated from the audio amplifier.

[0006]

【Example】

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 shows the power supply circuit of this invention. 2 is a main circuit diagram showing an embodiment of the circuit. In the figure, 1 is a power transformer, and the secondary side is composed of four diodes 2. Connected to bridge diode. One end of the output of bridge diode 2 is connected to a capacitor. grounded through the resistor 3, and connected to one end of the resistor 4 and the collector of the transistor 9. Connected. The other end of the bridge diode output is grounded. The other end of resistor 4 is Connected to the collector of transistor 5. The base of transistor 5 is connected via resistor 7. Connected to power on/off input terminal 6 and grounded via capacitor 8 . The emitter of transistor 5 is connected to the base of transistor 9. transition The emitter of the amplifier 9 is grounded via the capacitor 13, and the emitter of the audio amplifier 11 is connected to the ground via the capacitor 13. Connected to the power terminal. An audio signal is connected to the input terminal 10 of the audio amplifier 11. At the same time, a speaker 12 is connected to the output terminal.

[0007] In the above configuration, the power transformer 1 steps down the AC voltage and outputs the stepped down voltage to the secondary side. Strengthen. Bridge diode 2 performs full-wave rectification and is smoothed by smoothing capacitor 3. to supply current to Darlington transistors 5 and 9. Power on/off input When there is no signal at terminal 6, the base voltage of transistor 5 is 0V, and transistor 5 is cut off and no current is supplied to the audio amplifier 11. Power on/off input When a positive signal is input to terminal 6, the base voltage of transistor 5 becomes positive and the transistor Register 5 is turned on. When transistor 5 turns on, transistor 9 also turns on. A current is supplied to the audio amplifier 11, and the audio signal at the input terminal 10 is amplified and sent to the speaker. The signal is outputted from the switch 12. Choose appropriate values for resistor 7 and capacitor 8, and set the time constant appropriately. If the setting is set to Noise caused by the lance can be prevented. Also, the capacitor 8 has a current It functions as a ripple filter in the circuit.

[0008]

[Effect of the idea]

As described above, in this invention, the audio amplifier is opened and closed, and the audio amplifier is turned on. Removes noise and ripples in the current circuit until stable operation is achieved. It has the advantage of having three functions.

[Brief explanation of drawings]

FIG. 1 is a main circuit showing an embodiment of a power supply circuit of the present invention.

[Explanation of symbols]

1 Power transformer 2 Bridge diode 3 Capacitor 4 Resistance 5 Transistor 6 Power on/off input terminal 7 Resistance 8 Capacitor 9 transistor 10 Audio signal input terminal 11 Audio amplifier 12 speakers 13 capacitor

Claims (1)

[Scope of utility model registration request] Claim 1: In a power supply circuit for an audio amplifier that amplifies an audio signal, one end of a first capacitor is connected to the positive terminal of the power supply;
one end of the resistor and the collector of the first transistor are connected, the negative terminal of the power supply and the other end of the first capacitor are grounded,
The emitter of the first transistor is grounded via a third capacitor, and connected to the power supply terminal of the audio amplifier, and the input terminal of the audio amplifier is connected to the input of the audio signal,
A speaker is connected to the output terminal, a collector of a second transistor is connected to the other end of the first resistor, an emitter of the second transistor is connected to the base of the first transistor, and a base of the second transistor is connected to a second capacitor. A power supply circuit configured to be connected to the power supply connection/disconnection input terminal via a second resistor.