SU1480093A1 - Protection unit for transistor amplifier of cable broadcasting - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is the elimination of short-term overloads of the amplifier during emergency operation. The protection device contains an amplifier 1, a load 2, a limiting resistor 3, a voltage divider 4, a rectifier 5 and 6, a controlled transistor current limiter 7, a capacitor 8, a control key 9, a comparison unit 10, a trigger 11 and a block OR 12. In the case of reducing the load resistance below an acceptable level 2 there is an operation LIMITER 7 which limits LOAD CURRENT 2 at a predetermined level, without overloading AMPLIFIER 1. At the same time sharply increases the voltage drop across resistor 3. This leads to a trigger 11, OFF For prison LIMITER enable switch 7 and 9. The device goes into operation with LIMITER 7 through the load 2 with a resistor 3. After the cause of failure in the equipment returns to normal operation due to the trigger 11 OPENING AND CAPACITOR LIMITER 7. 8 eliminates the harmful influence of noise INDUSTRIAL FREQUENCY AT WORK DEVICE. 1 IL.

Description

The invention relates to radio engineering and can be used in wired broadcasting schemes in which a large number of independent loads are connected to a single power amplifier. The use of the invention. eliminates the effect of an accident in the circuit of any load on the operation of both the power amplifier and other loads.

The purpose of the invention is the elimination of short-term overloads of the amplifier during emergency operation.

The drawing shows an electrical block diagram of a device for protecting a transistor amplifier of wire broadcasting.

The device for protecting a transistor amplifier for wire broadcasting contains an amplifier 1, a load 2, a terminating resistor 3, a voltage divider 4, the first and second rectifiers 5, 6, a controlled transistor current limiter 7, a capacitor 8, a controlled key 9, and block 10. trigger, trigger 11, and OR block 12.

The protection device of the transistor amplifier of wire broadcasting works as follows.

I

When you turn on the device, the trigger

II opens the controlled key 9 and closes the simultaneously controlled transistor current limiter 7. The current through the load 2 is limited to a safe level for the amplifier 1 using a limiting resistor 3.

. When the output signal appears at the output of amplifier 1, the outputs of the comparison unit 10 receive the output voltages from the first and second rectifiers 5, 6. Moreover, if the load resistance 2 is not lower than the specified value, the output voltage of the second rectifier 6 exceeds the output voltage of the first rectifier 5. Because of this, the trigger 11 switches, closing the controlled key 9 and opening the controlled transistor current limiter 7, which shunts the terminating resistor 3. In this case, the protection device of the transistor amplifier Broadcasting goes into normal ’mode of operation.

If there is a decrease in load resistance 2 below the permissible level, then the controlled transistor current limiter will trip and limit the load current 2 at a given level without overloading amplifier 1. At the same time, the voltage drop across the limiting resistor 3 increases sharply, which triggers trigger 11, and turns off controlled transistor current limiter and the inclusion of a controlled key 9, the device enters the mode of operation with a current limiter through load 2 using a limiting resistor 3.

After eliminating the causes of the accident, the device will automatically return to normal operation due to the operation of the trigger 11 and the opening of the controlled transistor current limiter 7.

Capacitor 8 eliminates the harmful effects of industrial frequency interference on the operation of the device. The value of the capacitor 8 is selected so that the voltage with a frequency of 5 Hz is practically not transmitted through it to the input of the second rectifier 6.

Claims (1)

Claim A device for protecting a transistor amplifier of wire broadcasting, comprising an amplifier, a load connected in series with a limiting resistor, a trigger, a first rectifier, the output of which is connected to the first input of the trigger, a second rectifier, a controlled key, characterized in that, in order to eliminate short-term overloads of the amplifier in emergency conditions work, introduced in series connected the comparison unit and the OR block, controlled transistor current limiter, voltage divider and capacitor, while the divider voltage is connected between the output of the amp. a common rail and a common bus, the tap of the voltage divider through a capacitor is connected to the input of the second rectifier, the output of which is controlled by a key, connected to the input of the comparison unit, the control key input is connected to the trigger output and the second input of the OR block, the first and second outputs of the controlled transformer limiter 1480093 current are connected respectively to the first and second terminals of the limiting resistor, and the control input to the output of the OR block, the second input of the comparison unit is connected to the output of the first rectifier, the input of which th point is connected to the load connection and limiting resistor, a second input trig ger connected to the output of the comparison j Nia, the first terminal of the load connected to the output of the amplifier, and the second terminal of the limiting resistor - general shynoy.