Voltage to 4-20ma current circuit

Abstract

The invention discloses a circuit for converting voltage into 4-20mA current, relates to the technical field of converting voltage into current and comprises an operational amplifier U1, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a resistor R15, a resistor R16, a diode D1 and a triode Q1; one end of the resistor R11 is connected with the input voltage V0, and the other end ofthe resistor R11 is connected with the inverting input end of the operational amplifier U1; one end of the resistor R12 is connected with the positive phase input end of the operational amplifier U1,and the other end of the resistor R12 is grounded; one end of the resistor R13 is connected with the inverting input end of the operational amplifier U1, and the other end of the resistor R13 is connected with the anode of the diode D1; one end of the resistor R14 is connected with the positive phase input end of the operational amplifier U1, and the other end of the resistor R14 is connected withthe emitter of the triode Q1; one end of the resistor R15 is connected with the output end of the operational amplifier U1, and the other end of the resistor R15 is connected with the base electrodeof the triode Q1; one end of the resistor R16 is connected with the emitter of the triode Q1, and the other end of the resistor R16 is connected with the anode of the diode D1. The circuit has simplestructure and low cost.

Description

technical field [0001] The invention relates to the technical field of voltage-to-current conversion, in particular to a circuit for converting voltage to 4-20mA current. Background technique [0002] In the industrial control site, it is necessary to display the relevant information of each link of the system through the instrument, which is convenient for intuitive observation and monitoring, and judges whether the system is running normally. However, the instrument installed on site is generally far away from the main control equipment. , due to the distributed resistance on the transmission line, the voltage signal will have a certain attenuation during the transmission process, and at the same time, the transmission line will also be interfered by noise, which will cause a large error in the display result. The current signal has strong anti-interference ability on the transmission line, and will not generate voltage drop on the transmission line, which well avoids the ...

AI Technical Summary

Problems solved by technology

[0003] The existing 4-20mA current signal generation scheme generally adopts an integrated chip scheme, the chip input is voltage, and the chip output is current, but the price of this integrated chip is relatively expensive, which is not conducive to the mass production of the main control equipment, which limits its low-cost application in cost equipment

Moreover, the input and output of this scheme do not achieve electrical isolation. Since the industrial control site is generally more complicated, if there is a serious problem with the field instrument, it will also damage the main control equipment.

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