Circuit for realizing threshold LED indication by 4-20mA ultraviolet probe

Abstract

The invention discloses a circuit for realizing threshold LED indication of a 4-20mA ultraviolet probe, and relates to the technical field of ultraviolet probe circuits. The input end of the 4-20mA ultraviolet probe output 4-20mA current signal circuit is connected with 24V direct current, the output end of the 4-20mA ultraviolet probe output 4-20mA current signal circuit is connected with the differential operational amplifier circuit, the output end of the 4-20mA ultraviolet probe output 4-20mA current signal circuit is further connected with a first sampling resistor to a 4-20mA Out output end in series, the output end of the differential operational amplifier circuit is connected with the comparator circuit, and the comparator circuit is connected with the output end of the 4-20mA Out output end. The differential operational amplifier circuit and the comparator circuit form a current sampling comparison circuit, and the output end of the comparator circuit is connected with the first indicator light and the second indicator light through the LED drive circuit. According to the invention, transmission and power supply functions of 4-20mA current signals and an indication function when the current signals are larger than or smaller than a specific threshold are realized, the ultraviolet intensity is judged through the LED threshold indicator lamp, and the application prospect is wide.

Description

technical field [0001] The invention relates to the technical field of ultraviolet probe circuits, in particular to a circuit for realizing threshold LED indication by a 4-20mA ultraviolet probe. Background technique [0002] At present, all the UV probes on the market do not use the color of the LED to judge the size of the UV intensity, but the most widely used in the industry is to use the analog 4-20mA current signal to transmit temperature, pressure, speed, radiation value, etc., with It has the advantages of long transmission distance and strong anti-interference ability. The technical difficulties of the 4-20mA ultraviolet probe to realize the threshold LED indication circuit: [0003] ①The problem of sharing the power supply of the current sampling circuit and the LED driving circuit: as the change of the detected ultraviolet value is reflected in the change of the output current in the range of 4-20mA, the current sampling circuit and the LED driving circuit cannot...

AI Technical Summary

Problems solved by technology

[0003] ①The problem of sharing the power supply of the current sampling circuit and the LED driving circuit: as the change of the detected ultraviolet value is reflected in the change of the output current in the range of 4-20mA, the current sampling circuit and the LED driving circuit cannot obtain a stable working voltage and work Abnormal, and the resulting voltage drop may affect the signal acquisition of the device

[0004] ② Connect the current sampling circuit and the LED driving circuit in parallel between two signal lines for power supply: the power ground wire current generated when the current sampling circuit and the LED driving circuit are working is merged into the current signal output line, resulting in a significantly larger output current signal, seriously Affect measurement accuracy

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