CN105914836A - Charging-type portable pA micro current monitoring system - Google Patents
Charging-type portable pA micro current monitoring system Download PDFInfo
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- CN105914836A CN105914836A CN201610350167.XA CN201610350167A CN105914836A CN 105914836 A CN105914836 A CN 105914836A CN 201610350167 A CN201610350167 A CN 201610350167A CN 105914836 A CN105914836 A CN 105914836A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
Abstract
The invention relates to a charging-type portable pA micro current monitoring system. The system adopts a single lithium battery for a unit for storing and supplying electric energy, a low-power consumption and high-precision operational amplifier and a feedback circuit are adopted, with a pA-level micro current I/V conversion circuit as a core, through multiple anti-interference protection circuits, USB is selected for charging through a charging switch, system power supply is selected through a power supply selection switch, the system power supply comes from the USB in match with the lithium battery, and monitoring on the pA micro current is completed. The charging-type portable pA micro current monitoring system can be used as a portable measurement instrument and can be used indoors, outdoors and other places in need of monitoring, power supply by the lithium battery can be realized both indoors and outdoors, and power supply by the USB is also realized. The size of the monitor of the invention is only the size of a palm, the weight is light, carrying is facilitated, the monitoring precision is high, the price is low, the testing is convenient, and a corresponding conversion voltage value can be tested when to-be-monitored micro current is inserted according to requirements.
Description
Technical field
The present invention relates to micro-current monitoring field, particularly relate to the micro-current monitoring system of chargeable portable.
Background technology
The world is made up of a lot of materials, and the electronics in material is one of elementary particle, and electron motion can produce electric current.Small-signal is prevalent in human lives, such as the low light level, weak sound, weak magnetic, small capacitances, thin tail sheep and micro-pressure etc..Along with the very fast development of science and technology, a lot of fields all be unable to do without the measurement of weak current.In semiconductor production, insulating materials, the field such as faint detection, the generation of micro-electric current and test have highly important status, and the measurement scope of weak current is far below 10-mostly10A.Therefore, the technology measuring micro-electric current has wide application prospect in each field, significant.
Conventional pA monitor volume is very big, and power supply is the most chargeable, and weight is the biggest, is not easy to removable monitoring, cannot be carried out measuring at some ad-hoc locations.And major part is from external import, expensive, add use cost.
To this end, the present invention completes the high precision test of a kind of chargeable portable faint DC current of pA level.
Summary of the invention
The invention aims to overcome existing pA monitor volume big, weight is big, and power consumption is big, and wiring complexity is high, and price is high and the use inconvenience that causes, completes a kind of micro-current monitoring system for this present invention.Monitor size of the present invention is only hand size, is convenient for carrying, and plugs micro-electric current to be monitored on request and can test out the conversion voltage value of correspondence.
The present invention can be achieved through the following technical solutions:
The micro-current monitoring system of chargeable portable pA, this system realizes based on corresponding detection equipment, and this detection equipment includes device housings body, circuit board；Power switch, USB charging inlet, lithium battery, I/V change-over circuit, voltage generator, power supply selection switch are installed on circuit board；Circuit board is fixed in device housings body.Device housings body be a little cuboid of regular metal and inner upper circuit board before the centre of the space of a whole page fix I/V change-over circuit；Power switch, USB charging inlet switch, power supply selection switch it is provided with on the left of the circuit board of device housings body inner upper；Fixed voltage generator and micro-current monitoring external wiring terminal on the right side of the circuit board of shell body inner upper；The circuit board of shell body lower inside is provided with lithium battery interface, lithium battery fixing device.
The micro-current monitoring system of chargeable portable pA, this monitoring terminal includes that four is most of: I/V change-over circuit, electric power management circuit, protection circuit and interface circuit；
Electric power management circuit is connected with I/V change-over circuit, and I/V change-over circuit is connected with protection circuit, and meanwhile, the input/output terminal of I/V change-over circuit is connected with interface circuit.
Wherein, I/V change-over circuit is made up of I/V translation operation amplifier and current input terminal circuit；Electric power management circuit is made up of charge management circuit, power supply management circuit and battery voltage supervisory circuit；Protection circuit is made up of short-circuited conducting sleeve protection circuit, in large area circuit, BNC connector shielding line and metal shielding box.
This system use single lithium battery as the storage of electric energy and feeding unit, with I/V change-over circuit as core, it is possible to selecting charging modes to be that USB charges by charge switch, select switch to select system power supply by power supply, system power supply derives from USB and coordinates lithium battery.The output of single lithium battery output or external charging part is connected by native system with power supply circuit, purpose is to provide available high-quality to power for I/V change-over circuit, voltage generator, operational amplifier and other each circuit parts, meets power reguirements.
The each unit module realizing whole system function is respectively as follows: I/V conversion circuit unit, charhing unit, power supply unit, input block, protected location and interface unit；Wherein, charhing unit is connected with power supply unit, and power supply unit is connected with each circuit part, and voltage generator is connected with I/V change-over circuit, convenient debugging.Binding post all uses High Performance Insulation line to be connected with internal circuit, uses high-performance plug shield line to be connected with external measuring circuitry.
Below each several part modular unit is specifically described.
I/V conversion circuit unit includes operational amplifier, backfeed loop, inlet circuit unit.Wherein backfeed loop is connected with inverting input and the output of operational amplifier, and inlet circuit unit is connected with the inverting input of operational amplifier.
Charhing unit includes USB charging control circuit and voltage indicating circuit.USB charging control circuit is connected with voltage indicating circuit and battery.
Power supply unit includes mu balanced circuit, +/-2.5V bleeder circuit and battery electric quantity indicating circuit.Battery is connected with mu balanced circuit, and mu balanced circuit is connected with +/-2.5V bleeder circuit and battery electric quantity indicating circuit.
Input block includes the input that the micro-current input terminal of pA, opamp input terminal, feedback resistance and electric capacity connect.Wherein the micro-current input terminal of pA is connected with opamp input terminal, after feedback resistance and electric capacity are in parallel, is connected with inverting input and the output of operational amplifier.
Protected location includes short-circuited conducting sleeve protection circuit and metallic shield protector.Short-circuited conducting sleeve protection circuit is an independent loop, isolates external interference signal and enters PCB, thus protects whole circuit；Metallic shield, gets up circuit part cover, improves circuit anti-interference ability.
Interface unit includes input and output binding post, and binding post, the internal insulated conductor using high insulating property through shielding case are drawn and the anti-interference p-wire of high-insulativity.
Compared with prior art the present invention can obtain following beneficial effect.
The present invention, compared with current all kinds of micro-current monitoring systems, can arrange USB interface and be charged built-in lithium battery, and volume is little, price is low, be convenient for measuring, Portable belt and precision high.The circuit part of the present invention all uses low-power consumption Low-bias Current, high insulation Anti-interference Design, and whole system is run under the lowest power consumption, both saved the use of battery electric quantity so that equipment can work long hours in the case of the most battery powered.Thermal noise interference can be reduced again.The present invention is capable of micro-electric current pA and accurately monitors.The present invention can be placed on indoor or the outdoor and place of other needs monitorings as portable set, can connect USB charging in indoor and coordinate lithium battery to use, lithium battery power supply use.The present invention can as micro-electric current pA monitoring terminal, common universal meter can be coordinated to use, there is volume little, lightweight, be convenient for carrying, the feature of low-power consumption.
Accompanying drawing explanation
Fig. 1 is the structure principle chart of the present invention；
Fig. 2 .1 is the system protection circuit schematic diagram of the circuit board of the present invention；
Fig. 2 .2 is the I/V change-over circuit schematic diagram of the circuit board of the present invention；
Fig. 2 .3 is the voltage generating circuit schematic diagram of the present invention；
Fig. 3 .1 is the principle assumption diagram of USB charging circuit；
Fig. 3 .2 is the power circuit principle figure of the remaining circuit plate of the present invention；
Fig. 4 is the board structure of circuit block diagram of the present invention.
In figure: 1, protection circuit, 2, I/V change-over circuit, 3, voltage generator, 4, USB charging circuit, 5, power-supplying circuit, 6, +/-2.5V bleeder circuit, 7, battery electric quantity indicating circuit.
Detailed description of the invention
Below with reference to the drawings and specific embodiments, the invention will be further described.
Fig. 1 is the structure principle chart of the present invention, and used by the present invention, the operational amplifier of I/V change-over circuit is Low-bias Current, the accurate amplifier of low maladjustment voltage.The present invention, according to the computational methods of amplifying circuit, designs related circuit schematic diagram, the unsettled welding input of innovation, draw PCB.In view of the anti-interference problem of input, the most do not reserve input pad, but by all unsettled welding of the pin being connected with input, become an isolated input module that is independent and that around insulate.
Fig. 2 .1-2.3 is the circuit theory diagrams of the circuit board of the present invention.The circuit of circuit board includes system protection circuit 1, I/V change-over circuit 2, voltage generating circuit 3.The block diagram of total is as shown in Figure 4.
System protection circuit 1 includes short-circuited conducting sleeve protection circuit, in large area circuit and metallic shield protector.Short-circuited conducting sleeve protection circuit is an independent loop, isolates external interference signal and enters PCB, thus protects whole circuit；Whole circuit cover is got up by metallic shield, improves circuit anti-interference ability.
I/V change-over circuit 2 passes through high precision operating amplifier, bias current fA level, extremely low overshoot voltage, guarantees the precision that I/V changes.The micro-current input terminal of pA level passes through P1, P2 interface and super large resistance 100G, feedback capacity C4 and the amplification of amplifier so that 1pA correspondence output 0.1V voltage, is exported by the binding post of P3, P4 interface.Wherein C4 is as feedback capacity, it is desirable to ultralow electric leakage, and capacity is the least, is used for offsetting the influence of noise that the interpolar distribution capacity of operational amplifier brings, and has also deepened negative-feedback simultaneously, prevents circuit gain peaking, enters saturation state.Super large resistance is selected to reduce the noise jamming problem that weak current small resistor brings.P1, P2, P3 and P4 binding post uses the wire of internal high insulation, through the metal-back of shielding, and frame ground, to ensure high anti-interfering performance.The test lead being connected with binding post is also adopted by the wire of high insulating property, to prevent the interference of external environment.
Voltage generator circuit 3 is connected by connector with the input of I/V change-over circuit, thus provides debugging signal for whole circuit.The Current Voltage generator being connected with supply voltage-2.5V, produces 0.1V, 0.5V, 1V and 1.235V voltage respectively, after 100G resistance, becomes 1pA, 5pA, 10pA and 12.35pA respectively for experiment test.
Fig. 3 .1-3.2 is that the power circuit principle figure of the present invention includes USB charging circuit 4, power supply circuits 5, +/-2.5V bleeder circuit 6 and battery electric quantity indicating circuit 7.Wherein USB charging circuit 4 one end is connected with USB interface, and one end is connected with charging option switch, selects low-power chip, reference chip databook, the resistance of regulation programmable port, mates suitable electric capacity so that it is can be single lithium battery charging.Power supply circuits 5 are made up of power supply circuits, mu balanced circuit and bleeder circuit.Mu balanced circuit have selected low power consumption high-precision voltage stabilizing chip.In +/-2.5V bleeder circuit 6, R3, R4 resistance is equal, is divided equally by 5V voltage, and last amplifier follower determines the position tie point at R3 and R4 of ground connection, thus provides stable +/-2.5V power supply for system.R1 and the R2 tie point that the amplifier in-phase input end of battery electric quantity indicating circuit 7 does not waits with resistance is connected, and inverting input is connected with the tie point of R3 and R4 of equivalent resistance, Q1 control two red and green luminous diode indicating battery electric quantities.Power supply circuits 5 can select two kinds of powering modes, pattern one: USB charging to coordinate lithium battery work, pattern two: lithium battery works independently by switch.
When circuit is in pattern for the moment, stir charging option switch S1 select USB input and stir power supply selection switch S2 selection USB charging and lithium battery end, if USB charging can provide normal working voltage, i.e. power pack connects through lithium battery, it is system power supply by USB charging circuit, thus reduces the loss of battery electric quantity.When USB charging circuit is not provided that normal working voltage, selecting pattern two, toggle switch S2 i.e. power pack is connected with lithium battery, lithium battery be system power supply；
Using a n-channel enhancement-mode field-effect transistors in battery electric quantity LED display circuit 6, be equivalent to a switch, when electricity is enough, switching tube turns on automatically, and lamp LED2 below is bright, and when electricity deficiency, switching tube does not works, and LED1 lamp above is bright；
Other interface circuits 7 include USB interface, power interface and test interface, facilitate later test and system maintenance.USB interface and power interface are by protection ring protective separation, and use capacitor filtering, it is ensured that stable voltage.Measure interface and use BNC connector shielding line, wherein input, output P1, P2, P3 and P4 are connected on the BNC connector of can output, the other end is by shielding line outer layer strip off, middle core has reserved joint, the positive pole of test table can be connected on, screen layer has reserved joint can be connected on the negative pole of velocity metre, i.e. ground connection.
It is feasible that result after measured proves by the method for shielding line, and numerical value is very steadily accurately.
Claims (8)
1. the micro-current monitoring system of chargeable portable pA, this system is real based on corresponding detection equipment
Existing, this detection equipment includes device housings body, circuit board；Be provided with on circuit board power switch,
USB charging inlet, lithium battery, I/V change-over circuit, voltage generator, power supply select switch；
Circuit board is fixed in device housings body；Device housings body is the little cuboid of regular metal and an inside
Before the circuit board of top, I/V change-over circuit is fixed in the centre of the space of a whole page；Device housings body inner upper
Power switch, USB charging inlet switch, power supply selection switch it is provided with on the left of circuit board；Shell body
Fixed voltage generator and micro-current monitoring external wiring terminal on the right side of the circuit board of inner upper；Shell
The circuit board of body lower inside is provided with lithium battery interface, lithium battery fixing device；
It is characterized in that: this monitoring terminal includes four major part I/V change-over circuits, power management electricity
Road, protection circuit and interface circuit；
Electric power management circuit is connected with I/V change-over circuit, and I/V change-over circuit is connected with protection circuit
Connecing, meanwhile, the input/output terminal of I/V change-over circuit is connected with interface circuit；
Wherein, I/V change-over circuit is made up of I/V translation operation amplifier and current input terminal circuit；
Electric power management circuit is made up of charge management circuit, power supply management circuit and battery voltage supervisory circuit；
Protection circuit is by short-circuited conducting sleeve protection circuit, in large area circuit, BNC connector shielding line and metal screen
Cover box composition；
This system use single lithium battery as the storage of electric energy and feeding unit, with I/V conversion electricity
Road is core, it is possible to selects charging modes to be that USB charges by charge switch, is selected by power supply
Switch selects system power supply, and system power supply derives from USB and coordinates lithium battery；Native system is by single-unit lithium
The output of battery output or external charging part is connected with power supply circuit, it is therefore an objective to for I/V
Change-over circuit, voltage generator, operational amplifier and other each circuit parts provide available
High-quality is powered, and meets power reguirements；
The each unit module realizing whole system function is respectively as follows: I/V conversion circuit unit, charging list
Unit, power supply unit, input block, protected location and interface unit；Wherein, charhing unit and confession
Electric unit is connected, and power supply unit is connected with each circuit part, voltage generator and I/V conversion electricity
Road is connected, convenient debugging；Binding post all uses High Performance Insulation line to be connected with internal circuit, adopts
It is connected with external measuring circuitry with high-performance plug shield line.
The micro-current monitoring system of chargeable portable pA the most according to claim 1, its feature
It is: I/V conversion circuit unit includes operational amplifier, backfeed loop, inlet circuit unit；
Wherein backfeed loop is connected with inverting input and the output of operational amplifier, inlet circuit
Unit is connected with the inverting input of operational amplifier.
The micro-current monitoring system of chargeable portable pA the most according to claim 1, its feature
It is: charhing unit includes USB charging control circuit and voltage indicating circuit；USB charges control
Circuit processed is connected with voltage indicating circuit and battery.
The micro-current monitoring system of chargeable portable pA the most according to claim 1, its feature
It is: power supply unit includes mu balanced circuit, +/-2.5V bleeder circuit and battery electric quantity indicating circuit；
Battery is connected with mu balanced circuit, mu balanced circuit and +/-2.5V bleeder circuit and battery electric quantity instruction electricity
Road is connected.
The micro-current monitoring system of chargeable portable pA the most according to claim 1, its feature
It is: input block includes the micro-current input terminal of pA, opamp input terminal, feedback resistance
The input connected with electric capacity；Wherein the micro-current input terminal of pA is connected with opamp input terminal
Connect, after feedback resistance and electric capacity are in parallel, with inverting input and the output phase of operational amplifier
Connect.
The micro-current monitoring system of chargeable portable pA the most according to claim 1, its feature
It is: protected location includes short-circuited conducting sleeve protection circuit and metallic shield protector；Short-circuited conducting sleeve is protected
Circuit is an independent loop, isolates external interference signal and enters PCB, thus protects
Whole circuit；Metallic shield, gets up circuit part cover, improves circuit anti-interference ability.
The micro-current monitoring system of chargeable portable pA the most according to claim 1, its feature
Being: interface unit includes input and output binding post, binding post, inside through shielding case are adopted
Draw and the anti-interference p-wire of high-insulativity with the insulated conductor of high insulating property.
The micro-current monitoring system of chargeable portable pA the most according to claim 1, I/V turns
The operational amplifier changing circuit is Low-bias Current, the accurate amplifier of low maladjustment voltage；Native system is pressed
According to the computational methods of amplifying circuit, design related circuit, the unsettled welding input of innovation, draw
Printed circuit board (PCB)；In view of the anti-interference problem of input, the most do not reserve defeated
Enter and hold pad, but by all unsettled welding of the pin being connected with input, become one independent
With the input module isolated around insulated；
It is characterized in that: the circuit of circuit board includes system protection circuit (1), I/V change-over circuit
(2), voltage generating circuit (3)；
System protection circuit (1) includes short-circuited conducting sleeve protection circuit, in large area circuit and metallic shield
Cover protector；Short-circuited conducting sleeve protection circuit is an independent loop, isolates external interference signal and enters
PCB, thus protect whole circuit；Whole circuit cover is got up by metallic shield, improves
Circuit anti-interference ability；
I/V change-over circuit (2) is by high precision operating amplifier, bias current fA level, extremely low
Overshoot voltage, guarantee the precision that I/V changes；The micro-current input terminal of pA level is connect by P1, P2
Mouth and super large resistance 100G, feedback capacity C4 and the amplification of amplifier so that 1pA correspondence is defeated
Go out 0.1V voltage, exported by the binding post of P3, P4 interface；Wherein C4 is as feedback electricity
Holding, it is desirable to ultralow electric leakage, capacity is the least, is used for offsetting the interpolar distribution capacity of operational amplifier
The influence of noise brought, has also deepened negative-feedback simultaneously, has prevented circuit gain peaking, enter saturated
State；Super large resistance is selected to reduce the noise jamming problem that weak current small resistor brings；P1、
P2, P3 and P4 binding post uses the wire of internal high insulation, through the metal-back of shielding, and
Frame ground, to ensure high anti-interfering performance；The test lead being connected with binding post is also adopted by height
The wire of insulating properties, to prevent the interference of external environment；
Voltage generator circuit (3) is connected by connector with the input of I/V change-over circuit,
Thus provide debugging signal for whole circuit；The Current Voltage being connected with supply voltage-2.5V occurs
Device, produces 0.1V, 0.5V, 1V and 1.235V voltage respectively, after 100G resistance, point
Do not become 1pA, 5pA, 10pA and 12.35pA for experiment test；
Power circuit includes USB charging circuit (4), power supply circuits (5), +/-2.5V dividing potential drop
Circuit (6) and battery electric quantity indicating circuit (7)；Wherein USB charging circuit (4) one end with
USB interface is connected, and one end is connected with charging option switch, selects low-power chip, reference chip
Databook, the resistance of regulation programmable port, mates suitable electric capacity so that it is can be single-unit
Lithium cell charging；Power supply circuits (5) are made up of power supply circuits, mu balanced circuit and bleeder circuit；Surely
Volt circuit have selected low power consumption high-precision voltage stabilizing chip；R3, R4 in +/-2.5V bleeder circuit (6)
Resistance is equal, is divided equally by 5V voltage, last amplifier follower determine the position of ground connection at R3 and
The tie point of R4, thus provide stable +/-2.5V power supply for system；Battery electric quantity indicating circuit
(7) R1 and the R2 tie point that amplifier in-phase input end does not waits with resistance is connected, anti-phase defeated
Enter end to be connected with the tie point of R3 and R4 of equivalent resistance, red and green luminous by Q1 control two
Diode indicating battery electric quantity；Power supply circuits (5) can select two kinds of powering modes by switch,
Pattern one: USB charging coordinates lithium battery work, pattern two: lithium battery works independently；
When circuit is in pattern for the moment, stir charging option switch S1 select USB input and
Stirring power supply selects switch S2 to select USB charging and lithium battery end, if USB charging can carry
Connect through lithium battery for normal working voltage, i.e. power pack, USB charging circuit be that system supplies
Electricity, thus reduce the loss of battery electric quantity；When USB charging circuit is not provided that normal working voltage,
Selection pattern two, toggle switch S2 i.e. power pack is connected with lithium battery, lithium battery be that system supplies
Electricity；
Battery electric quantity LED display circuit (6) use a n-channel enhancement mode field-effect brilliant
Body pipe, is equivalent to a switch, and when electricity is enough, switching tube turns on automatically, lamp LED2 below
Bright, when electricity deficiency, switching tube does not works, and LED1 lamp above is bright；
Other interface circuits (7) include USB interface, power interface and test interface, convenient with
After test and system maintenance；USB interface and power interface are by protection ring protective separation, and adopt
With capacitor filtering, it is ensured that stable voltage；Measure interface and use BNC connector shielding line, the most defeated
Enter, output P1, P2, P3 and P4 are connected on the BNC connector of can output, the other end
By shielding line outer layer strip off, middle core has reserved joint, it is possible to be connected on the positive pole of test table, screen
Cover layer to have reserved joint and can be connected on the negative pole of velocity metre, i.e. ground connection；
It is feasible that result after measured proves by the method for shielding line, and numerical value is the most steady
Accurately.
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| CN109709151A (en) * | 2019-01-30 | 2019-05-03 | 南通大学 | A kind of thin dielectric film electrical properties measuring system |
| CN109799378A (en) * | 2019-01-08 | 2019-05-24 | 北京交通大学 | A kind of micro-current sensing circuit |
| CN112290899A (en) * | 2020-10-26 | 2021-01-29 | 杭州爱华仪器有限公司 | Measuring circuit preamplifier |
| CN112505536A (en) * | 2020-11-13 | 2021-03-16 | 上海金智晟东电力科技有限公司 | Weak signal anti-interference measurement method |
| CN112798855A (en) * | 2020-12-29 | 2021-05-14 | 北京无线电计量测试研究所 | Fly-ampere-level direct-current micro-current signal measuring system |
| CN114624500A (en) * | 2022-04-20 | 2022-06-14 | 四川大学 | Precision measurement system for pA-level weak current |
| CN115763213A (en) * | 2022-11-22 | 2023-03-07 | 广东智普生命科技有限公司 | Micro-current detection system capable of being charged on line for electrospray source |
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| CN115763213A (en) * | 2022-11-22 | 2023-03-07 | 广东智普生命科技有限公司 | Micro-current detection system capable of being charged on line for electrospray source |
| CN115763213B (en) * | 2022-11-22 | 2023-11-14 | 广东智普生命科技有限公司 | Micro-current detection system capable of being charged online for electrospray source |
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| Publication number | Publication date |
|---|---|
| CN105914836B (en) | 2019-03-22 |
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