SU1376231A1 - Push-pull power amplifier - Google Patents

Abstract

Invention m. used to reproduce audio signals. The purpose of the invention is to reduce the power dissipation during an overload. ke and short circuit load. U-l contains a pre-output cascade made on transistors (T) 1 and 2, resistors 3 and 4, bias circuit 5, output stage made on T 6 and 7, current sensors 8 and 9, protective T 12 and 13. Newly entered matching circuits 10 and II, resistors 16 and 17 and a relay el-t, made on the key T 14 and 15, with different structure, resistors 18 and 19. 1 ill.

Description

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The invention relates to electronics and can be used to reproduce audio signals.

The purpose of the invention is to reduce the power dissipation during an overload and short circuit load.

In the drawing there is a circuit diagram of a push-pull power amplifier,

The two-cycle power amplifier contains a pre-output cascade, implemented on the first and second 2 transistors, resistors 3 and 4, circuit 5 offset 15 NIN, the output stage executed on

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third 6 and fourth 7 transistors, first 8 and second 9 current sensors, first 10 and second 11 matching circuits, first 12 and second 13 protective 20 transistors, a relay element made on the first 14 and second J5 key transistors, first 16,

second 17, third 18, fourth j9 resistors.

Push-pull power amplifier works as follows.

The input of the device, the base of transistors 1 and 2, is connected to the output of the phase-inertial cascade, which simultaneously performs the function of generating the displacement currents of transistors 1 and 2 (not shown). with the help of resistors 3 and 4 in the emitter circuits, which exert a heat stabilizing effect. In the absence of an input signal from the phase-inverse stage, the Q-current of the output stage at transistors 6 and 7 is determined by the voltage drop on the initial bias circuit 5.

When an input signal appears from a phase-inversion stage, depending on its sign, the upper or lower (according to the drawing) arm of a push-pull power amplifier works, with a trans-13762312

the transistor 14 (15) of the relay element, causing an avalanche-like opening of the transistor 15 (14).

Parts of the collector currents of transistors J4 and 15, which flowed through resistors 16 and J7, open transistors 12 and J3, which shunt the input of the device in both alternating and direct current. The latter leads to a complete cutoff of the collector currents of transistors 1,2 and 6,7. The output of the push-pull power amplifier is galvanically disconnected from the load.

In order to bring the push-pull power amplifier to the working state, it is necessary to eliminate the cause of the overload and to make the power switch on again.

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Claims (1)

Invention Formula A two-stroke power amplifier containing a pre-output cascade made on the first and second transistors having a different structure, connected in a common emitter circuit, whose emitters are connected to the power supply source through appropriate resistors, the bases are the two-stroke power amplifier inputs, and the collectors are connected through a circuit bias, the output stage, performed on the third and fourth transistors having a different structure, connected according to a circuit with a common collector, the collectors of which are respectively The first and second current sensors are connected to the power supply source, the first and second protective transistors have a different structure, the collectors of which are connected to the bases of the first and second pre-output transistors, respectively, and the emitters to the corresponding power supply source, characterized in that reduce the power dissipation in case of overload and short circuit load, the first and second matching circuits, the first and second resistors and a relay element, implemented on the first and second key transistors, are introduced rah having a different structure, third and fourth rezisvistory J and 2, for amplify the signal voltage. Matching circuits 10 and II, bring the signal levels from sensors 8 and 9 to the opening levels of transistors J4 and J5. When reaching the collector tog-tori, with the collectors of the third The transistor 6 (7) of any arm of the magnitude corresponding to the overload, which may be caused by a short circuit in the load, begins to open the fourth transistor through the first and second matching circuits respectively to the bases of the first and second key five 0 0 Q five five 0 Invention Formula A two-stroke power amplifier containing a pre-output cascade made on the first and second transistors having a different structure, connected in a common emitter circuit, whose emitters are connected to the power supply source through appropriate resistors, the bases are the two-stroke power amplifier inputs, and the collectors are connected through a circuit bias, the output stage, performed on the third and fourth transistors having a different structure, connected according to a circuit with a common collector, the collectors of which are respectively The first and second current sensors are connected to the power supply source, the first and second protective transistors have a different structure, the collectors of which are connected to the bases of the first and second pre-output transistors, respectively, and the emitters to the corresponding power supply source, characterized in that reduce the power dissipation in case of overload and short circuit load, the first and second matching circuits, the first and second resistors and a relay element, implemented on the first and second key transistors, are introduced rah having a different structure, third and fourth rezisi fourth transistors respectively through first and second matching circuits are connected to the bases of the first and second key 31376231. transistors, whose collectors through the first and second respectively, the third and fourth resistors, are connected to the co-resistors; they are connected to the bases of the second and first, respectively, the second and first key transistors, and The bases of the first are connected to the corresponding buses of the second protective transistors through the power supply.