JPS593604Y2 - Denryokuzoufukuki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in power amplifiers, and more particularly to class B (Class AB) push-pull amplifiers.

In conventional power amplifiers, no device is installed to indicate whether or not the amplifier is operating normally, regardless of whether an input signal is applied to the amplifier.

Furthermore, no device was provided to display the output in response to the input signal.

The object of the present invention is to provide a power amplifier equipped with a device that displays whether or not the amplifier is in a normal state when no input signal is applied to the amplifier, without increasing the number of components required for the power amplifier. Our goal is to provide the following.

Another object of the present invention is to provide a power amplifier equipped with a device for displaying output according to human input signals without increasing the number of required components.

The following description will be made with reference to the accompanying drawings. FIG. 1 shows a circuit of a conventional class B push-pull amplifier.

In this circuit, when no signal current is flowing through the transformer T1, the idling current that operates the power transistors Q1 and Q uses the forward voltage drop of the diode D0 from the current flowing through the resistor R1 and the diode D1 to the ground 1. and from the center of the transformer T1 respectively power transistors Q1. It flows through the base emitter of Q2, through resistor R2, and to ground 2.

Further, when a signal current is applied to the transformer T□, an alternating current signal current flows correspondingly.

This AC signal current passes from the ground 1 to the diode D1 and the center of the transformer T1, respectively, to the power transistor Q1.
．． Resistor R2, ground 2 via the base emitter of Q2
flows in an AC loop leading to .

Therefore, when an AC signal radio wave flows, the DC current flowing through the diode D1 decreases.

This invention focuses on the above-mentioned matters, and is shown in Figure 2.
The circuit is shown when applied to a class push-pull amplifier.

Here, the difference from the circuit of FIG. 1 is that a light emitting diode D2 is used instead of the diode D1.

(The same reference numerals indicate the same parts as in FIG. 1.

) As is clear from the above explanation, since the light emitting diode D2 is connected in series with the human input signal source, when no alternating current signal current flows, only a direct current flows from the light emitting diode D2 in the direction of ground 1. The diode emits light.

However, when an AC signal current is applied, the DC current is canceled out in proportion to the magnitude of the signal current, so the resistance R1
By selecting a relatively large value, the luminance of the light emitted by the diode h changes depending on the strength of the signal current.

(When the signal input is small and the impedance of the diode D2 is small, the brightness increases and becomes bright; when the signal input is large and the impedance of the light emitting diode D2 becomes large, the brightness decreases.) Therefore, it works as an indicator based on the input signal.

Therefore, the present invention can indicate whether the power amplifier is operating normally without increasing the number of components in the conventional circuit.

[Brief explanation of the drawing]

Figure 1 shows the circuit of a conventional class B push-pull amplifier.
FIG. 2 is a circuit diagram of a class B push-pull amplifier using light emitting diodes, which is an embodiment of the present invention. Explanation of symbols, R1, R2...Resistance, T1. T2
......Transformer, Ql, Q2...Power transistor, D□...Diode, SP...
...Speaker 1, 2...Ground, D2
・・・・・・Light-emitting diode.

Claims (1)

[Scope of utility model registration request] A light emitting diode is connected to the power source through a resistor in the forward direction, and this light emitting diode is placed between the base and emitter of the output transistor to stabilize the output transistor, and the light emitting diode is connected in series to the input signal source. A power amplifier circuit configured to set the value of the resistor so that the brightness of the light emitting diode changes depending on the magnitude of the signal from the input signal source connected to the input signal source.