CN202256478U - Practical digital ampere meter - Google Patents

Abstract

The utility model provides a practical digital ampere meter. The utility model relates to a current sensor. The practical digital ampere meter includes an I/U converting circuit, an emitter follower, an instrumental amplifying circuit and a single-chip microprocessor minimum system. The fundamental of the practical digital ampere meter is that a four wire system is adopted. Three 20 micro Omega current detecting resistor are connected in series to work as a current detecting terminal. An operational amplifier is utilized for isolating the circuit. The I/U converting circuit is utilized to converting current signals to voltage signals. An output voltage is amplified to 0 to 2.5 V through the instrumental amplifying circuit. The current sensor is provided with three adjustable range switches. The adjustable ranges of the switches are respectively, 0-20 mA, 0-200 mA, 0-2 A. The operation method includes steps of connecting a branch of currents to be measured in series and connecting an output terminal with a monitoring instrument or a microprocessor system. The practical digital ampere meter in the utility model can be applied for occasions of monitoring or controlling the currents on line. Compared with the prior art, the practical digital ampere meter in the utility model has characteristics of simple principle, low manufacturing cost and high measuring precision.

Description

A kind of practical digital reometer

Technical field

The utility model relates to a kind of electronic installation, and particularly a kind of current sensor apparatus can be applicable to small-sized digital current source and small-sized digital voltage source etc. and need carry out in the small electrical power apparatus of real-time current monitoring and control.

Background technology

Electronic failure 60% from power supply, therefore, the importance of power issue highlights day by day.Power-supply device has merged increasing new technology at present, for example Switching Power Supply, hard switching, soft switch, parameter voltage stabilizing, linear feedback voltage stabilizing, magnetrol technology, numerical controlled voltage, PWM, electromagnetic compatibility or the like.Actual demand directly promotes the continuous development and progress of power technology; In order to detect automatically and the demonstration electric current; And, harm situation such as overcurrent, overvoltage have automatic protection functions when taking place; Power technology with sensing detection, sense samples, sensing protection becomes Development Trend, and the detection current sensor just arises at the historic moment and is being widely used.

Summary of the invention

It is a kind of practical digital reometer that but summary of the invention the object of the present invention is to provide a kind of device of on-line monitoring electric current.

Solve the technical scheme of the utility model technical matters: the utility model comprises current detecting and amplifying circuit, A/D modules A DC0809, single-chip microcomputer main control module, driver module and LED display module, reset circuit and crystal oscillating circuit.The output terminal of current detecting and amplifying circuit connects the input end of A/D modules A DC0809; The input end of the output terminal of A/D modules A DC0809 and single-chip microcomputer main control module AT89C51 links; In addition two input ends of main control module link with the output terminal of reset circuit and crystal oscillating circuit respectively; The output terminal of main control module connects the input end of driving circuit, and the output terminal of driving circuit connects the LED display module.Said current detecting is by three 20m Ω current sense resistor R1, and R7, R9 connect and realize; The I/U change-over circuit comprises that the copped wave of assembly ICL7650 type is from the accurate amplifier (U1) of steady zero formula; Emitter follower circuit comprises component N PN transistor JE9013 (Q1), 5.1K resistance R 8,3K resistance R 11; Said instrument amplifying circuit comprises that assembly share the general low-power consumption amplifier of a slice LM328 type (U2A, U2B), uses a slice LM328 (U3A) separately, and resistance is the resistance (R2, R3, R10, R12) of 10K.Be provided with in the utility model to pass and change compound circuit that circuit, emitter follower and instrument amplifying circuit form and the three range pick-up units that contain current sensor by I/U.

Compare with the prior art product, it is simple to the utlity model has principle, inexpensive, the characteristics that measuring accuracy is high.Through measured value and the contrast of preparation value of checking three to measure gear, relative error does not all have to surpass 4%.

Description of drawingsFig. 1 is the theory diagram of the utility model, and Fig. 2 is the circuit theory diagrams of the utility model

EmbodimentReferring to Fig. 1 and 2, the utility model comprises current detecting and amplifying circuit, A/D modules A DC0809, single-chip microcomputer main control module, driver module and LED display module, reset circuit and crystal oscillating circuit.The output terminal of current detecting and amplifying circuit connects the input end of A/D modules A DC0809; The input end of the output terminal of A/D modules A DC0809 and single-chip microcomputer main control module AT89C51 links; In addition two input ends of main control module link with the output terminal of reset circuit, crystal oscillating circuit respectively; The output terminal of main control module connects the input end of driving circuit, and the output terminal of driving circuit connects the LED display module.Said current detecting is connected and is realized by three 20m Ω current sense resistor R1, R7, R9; The I/U change-over circuit comprises that the copped wave of assembly ICL7650 type is from the accurate amplifier (U1) of steady zero formula; Emitter follower circuit comprises component N PN transistor JE9013 (Q1), 5.1K resistance R 8,3K resistance R 11; Said instrument amplifying circuit comprises that assembly share the general low-power consumption amplifier of a slice LM328 type (U2A, U2B), uses a slice LM328 (U3A) and the resistance resistance (R2, R3, R10, R12) as 10K separately; Said power supply indicating section comprises light emitting diode (D1, D2, D3) and 330 Europe resistance (R13, R14, R15).Current detecting and amplifying circuit (1) input A/D modules A DC0809 (2) by front end; Generate digital signal input single-chip microcomputer main control module (3); Control and driving module (4) and LED display module (5) show, also comprise peripheral reset circuit (6) and crystal oscillating circuit (7).Three current ranges are respectively 20mA, 200mA, 2A.The arrow on the left side is represented 4 joints of instrument among the figure.S is a range switch.4 amplifiers (U1, U2A, U2B, U3A) have been used in the circuit.For improving accuracy of measurement and reducing drift, U1 adopts the copped wave of ICL7650 type from the accurate amplifier (IC1) of steady zero formula.U2A and U2B share the general double operational of a slice LM358 type low-power consumption (IC2), and U3A uses a slice LM358 (IC3, the existing wherein one group of amplifier of only using) separately.U1 employing ± 5V dual power supply.For improving the ability of output current, constitute the one-level emitter follower by NPN transistor JE9013 (Q1).R11 ~ R13 is equivalent to the reometer internal resistance R1 among Fig. 1.When R1 selects 1.000 Ω, 10.00 Ω, 100.0 Ω successively; Current range is followed successively by 2A, 200 mA, 20 mA; Utilize R1 and (U1, U2A, U2B, U3A) to convert current signal to 0 ~ 2.5V voltage signal; Voltage signal changes device chip ACD0809 with A/D and links to each other, and links with SCM system.

Claims (3)

1. practical digital reometer; Comprise current detecting and amplifying circuit, A/D modules A DC0809, single-chip microcomputer main control module, driver module and LED display module, reset circuit and crystal oscillating circuit; The output terminal of current detecting and amplifying circuit connects the input end of A/D modules A DC0809; The input end of the output terminal of A/D modules A DC0809 and single-chip microcomputer main control module AT89C51 links; In addition two input ends of main control module link with the output terminal of reset circuit and crystal oscillating circuit respectively; The output terminal of main control module connects the input end of driving circuit, and the output terminal of driving circuit connects the LED display module, and it is characterized in that: said current detecting is connected and realized by three 20m Ω current sense resistor R1, R7, R9; The I/U change-over circuit comprises that the copped wave of assembly ICL7650 type is from the accurate amplifier (U1) of steady zero formula; Emitter follower circuit comprises component N PN transistor JE9013 (Q1), 5.1K resistance R 8,3K resistance R 11; Said instrument amplifying circuit comprises that assembly share the general low-power consumption amplifier of a slice LM328 type (U2A, U2B), uses a slice LM328 (U3A) and the resistance resistance (R2, R3, R10, R12) as 10K separately.

2. a kind of practical digital reometer as claimed in claim 1, its spy is to be provided with in the utility model by the I/U biography and changes the compound circuit that circuit, emitter follower and instrument amplifying circuit fine horse become.

3. a kind of practical digital reometer as claimed in claim 1, its spy is to be provided with in the utility model the three range pick-up units that contain current sensor.

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