SU1552350A1 - Current amplifier - Google Patents

Abstract

This invention relates to automation. The purpose of the invention is to reduce power consumption while simplifying. The current amplifier comprises an operational amplifier 1, transistors 2 and 3 of opposite structure, current sensors 4 and 5, a resistor 6 and feedback resistors 7 and 8. The presence at the input of the current amplifier signal of positive polarity leads to unlocking of the transistor 2 and the flow of current of positive polarity in the load. When changing the polarity of the input signal, the amplifier works in a similar way. Since the load can be inductive, the current amplifier circuit uses diodes connected respectively to the anode, cathode to the output of the current amplifier and cathode, to the anode to the corresponding power supply buses. To ensure the stability of the current amplifier with an inductive load, the resistors 7 and 8 are bridged by capacitors. 1 il.

Description

i i L4hJ

This invention relates to an automatic circuit and to be used as an amplifier operating on inductive loads.

The purpose of the invention is to reduce power consumption while simplifying.

The drawing shows a circuit diagram of a current amplifier.

The current amplifier includes an operational amplifier 1, the first and second transistors 2 and 3 of the opposite structure, the first and second current sensors 4 and 5, the first resistor 6, and the first and second feedback resistors 7 and 8.

The current amplifier operates as follows.

In the absence of an input signal and the equality of positive and negative voltages on the power supply buses, the current in the load is zero. The presence of a signal at the input of the current amplifier, for example, of a positive polarity, leads to the unlocking of the first transistor 2 and the leakage in the load of the current of positive polarity. Neglecting an imbalance in the current consumption of the operational amplifier 1 in the absence of an input signal and taking into account that the resistance of the first and second resistors 7 and 8 is substantially greater than the resistance of the first and second sensors 4 and 5 of the current (by 3–4 times d), currents:

them

R.

. (J2QKr I l "ii) ml of R,

where Eve „is the input signal;

U-pcs are equal in absolute value to the voltage on the pins of the power supply; TC - current in the load; H (- resistance of the first resistor 6;

R, is the resistance of the first feedback resistor 7;

R, is the resistance of the second feedback resistor 8;

R4 is the resistance of the first current sensor 4. expressions (1) receive

 -5i

Bx

1H or Tn

K1

s

(2) 55

Q

j

0

five

0

40

45

55

where K is the coAAciement factor

by current; I8x Uftk / I, - input current.

When changing the polarity of the input signal, the amplifier works in a similar way. Since the load may have a inductive. character, in the current amplifier circuit, diodes are used that are connected, respectively, by the anode, the cathode to the output of the current amplifier and the cathode, and the anode to the corresponding buses of the power supply. To ensure the stability of the current amplifier with an inductive load, the first and second feedback resistors 7 and 8 are shunted by capacitors (shown by dotted lines). I

The proposed current amplifier is simpler known and, in addition, there is no power loss at the output of the operational amplifier.

Claims (1)

Invention Formula The current amplifier containing the operational amplifier, the first and second transistors of the opposite structure, the first and second current sensors, the input resistor, and the first and second feedback resistors, the first terminals of which are connected to the non-inverting input of the operational amplifier, and the second terminals to the first terminals relevant current sensors, the second terminals of which are connected to the corresponding power supply buses, the first output of the input resistor being the input of the device, and its second output is connected to The rotating input of the operational amplifier, characterized in that, in order to reduce power consumption while simplifying, the bases of the first and second transistors are combined and connected to the output of the operational amplifier, their emitters are combined and the output of the device, the collectors are connected to the second terminals corresponding feedback resistors, the inverting input of the operational amplifier is connected to the common bus, and its power terminals are connected to the first terminals of the respective current sensors.