CN206114777U - Seven and half high accuracy wide -range resistance measurement appearance - Google Patents
Seven and half high accuracy wide -range resistance measurement appearance Download PDFInfo
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- CN206114777U CN206114777U CN201621089005.7U CN201621089005U CN206114777U CN 206114777 U CN206114777 U CN 206114777U CN 201621089005 U CN201621089005 U CN 201621089005U CN 206114777 U CN206114777 U CN 206114777U
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Abstract
Seven and half high accuracy wide -range resistance measurement appearance belongs to resistance measurement technical field. The utility model relates to a to solve present resistance measurement instrument precision low, the limited problem of range ability. Seven and half high accuracy wide -range resistance measurement appearance, display, optoelectronic isolation circuit, constant current source and amplifier circuit are connected simultaneously to the singlechip, optoelectronic isolation circuit connection AD converting circuit, AD change circuit connection amplifier circuit, the current output terminal of constant current source connects a stylus's current input and no. Two stylus's current input simultaneously, amplifier circuit's current input connects a stylus's current output terminal and no. Two stylus's current output terminal simultaneously, the display includes 8 charactrons and hd7279 display driving chip. The utility model is suitable for a milliohm level resistance to no nominal value carries out accurate measurement.
Description
Technical field
The utility model belongs to resistive measurement field.
Background technology
Minitype resistance accurate measurement is needed to use special microhmmeter, but the range ability of microhmmeter is limited, measurement
Slightly larger resistance when just outrange, be accomplished by being measured using other precision electrical meters in this case.The function of measuring resistance needs two
Species instrument realizes that either microhmmeter or other instruments, have that precision is low.Additionally, the country is seven and half
Also in the starting stage in ammeter design, the ammeter design for merging microhmmeter is not also proposed.
Utility model content
The utility model is, range ability limited problem low in order to solve existing resistance apparatus precision, is now provided
Seven and half high-accuracy wide-range resistance measuring instruments.
Seven and half high-accuracy wide-range resistance measuring instruments, it includes：Display 1, single-chip microcomputer 2, photoelectric isolating circuit 3, perseverance
Stream source 4, amplifying circuit 5,6, stylus 7 of A/D converter circuit and No. two stylus 8；
The display signal input part for showing signal output part connection display 1 of single-chip microcomputer 2, the filtering signal of single-chip microcomputer 2
The filtering signal output end of the defeated connection photoelectric isolating circuit 3 of input, the digital signal input end connection AD of photoelectric isolating circuit 3 turns
The digital signal output end of circuit 6 is changed, the analog signal of the input end of analog signal connection amplifying circuit 5 of A/D converter circuit 6 is defeated
Go out end, the current controling signal output end of single-chip microcomputer 2 connects the current controling signal input of constant-current source 4, the amplification of single-chip microcomputer 2
Control signal output connects the amplification control signal input of amplifying circuit 5, and the current output terminal of constant-current source 4 connects one simultaneously
The current input terminal and the current input terminal of No. two stylus 8 of number stylus 7, the voltage input end of amplifying circuit 5 connects No. one simultaneously
The voltage output end of the current output terminal of stylus 7 and No. two stylus 8；
Display 1 includes 8 charactrons and hd7279 display driver chips, and hd7279 display driver chips are used to drive 8
Individual numeral method numeral, single-chip microcomputer 2 show signal output part connect simultaneously hd7279 display driver chips CS ports,
CLK ports, DATA ports and KEY ports.
Constant-current source 4 includes：SN74LS145N constant-current source decoding chips, relay K1, relay K2, relay K3, relay
Device K4, relay K5, relay K6, relay K7, LM399 reference voltage source chip, resistance R0, resistance R1, resistance R2, resistance
R3, resistance R4, resistance R5, resistance R6, resistance R7, resistance R8, resistance R9, resistance R10, Nmos pipe Q1, Pmos pipe Q2, No. one put
Big device and No. two amplifiers；
The A ports of SN74LS145N constant-current source decoding chips, B ports and C-terminal mouth are simultaneously as the current control of constant-current source 4
Signal input part, the drain electrode of Pmos pipe Q2 as constant-current source 4 current output terminal, the C of SN74LS145N constant-current source decoding chips
Port and earth terminal connect power supply ground simultaneously, and the power end of SN74LS145N constant-current source decoding chips connects positive source,
The Y0 ports of SN74LS145N constant-current source decoding chips, Y1 ports, Y2 ports, Y3 ports, Y4 ports, Y5 ports and
Y6 ports are respectively used to control relay K1, relay K2, relay K3, relay K4, relay K5, relay K6 and relay
The coil of device K7 obtains electric or power failure state,
One end of resistance R3, one end of resistance R4, one end of resistance R5, one end of resistance R6, one end of resistance R7, resistance
One end of one end, one end of resistance R9 and resistance R10 of R8 connects positive source simultaneously, the other end of resistance R4, resistance R5
The other end, the other end of resistance R6, the other end of resistance R7, the other end of resistance R8, the other end of resistance R9 and resistance R10's
The other end connects respectively contact one end of relay K1, contact one end of relay K2, contact one end of relay K3, relay
Contact one end of contact one end of K4, contact one end of relay K5, contact one end of relay K6 and relay K7, relay
The contact other end of K1, the contact other end of relay K2, the contact other end of relay K3, relay K4 contact it is another
The contact other end at end, the contact other end of relay K5, the contact other end of relay K6 and relay K7 connects simultaneously
The source electrode of Pmos pipe Q2 and the inverting input of No. two amplifiers, the output end of No. two amplifiers connects the grid of Pmos pipe Q2,
The other end of resistance R3 connects the drain electrode of Nmos pipe Q1 and the normal phase input end of No. two amplifiers, Nmos pipe Q1 simultaneously
Source electrode connect the reverse input end of an amplifier and one end of resistance R0 simultaneously, another termination power ground of resistance R0,
The grid of Nmos pipe Q1 connects the output end of an amplifier, and the positive input of an amplifier connects the one of resistance R1 simultaneously
End and one end of resistance R2, the other end of resistance R1,1 pin of LM399 reference voltage source chips and 3 pin are connecting power supply just simultaneously
Pole, the other end of resistance R2,2 pin of LM399 reference voltage source chips and 4 pin connect power supply ground simultaneously.
The utility model is seven and half high-accuracy wide-range resistance measuring instruments, can be recognized and automatically to the milliohm without nominal value
Level resistance is accurately measured, while integrated larger resistance measurement function.The utility model is using seven and half tables in 2 Ω～2K
High-acruracy survey in Ω, realizes the precision in the gear stage that microhmmeter is not accomplished.
The utility model has the characteristics that compared with the microhmmeter of market same level precision：Range ability is up to 0.5m Ω
To 20M Ω, seven and half precise results are shown, 2 more than Ω ranges can accomplish the relative error in 15ppm, can accomplish in 2 below Ω
The technical requirements of ± 0.01% reading ± 5 word, measurement scheme voltammetry is simpler than bridge method, simple to operate.
Description of the drawings
Fig. 1 is the structured flowchart of seven and half high-accuracy wide-ranges resistance measuring instrument described in the utility model；
Fig. 2 is the circuit diagram of constant-current source；
Fig. 3 is the circuit diagram of amplifying circuit；
Fig. 4 is the circuit diagram of A/D converter circuit；
Fig. 5 is the circuit diagram of photoelectric isolating circuit, wherein,
One end of resistance R22 in electronic circuit shown in Fig. 5 a, the VE ports of 6N137 photo-couplers and 6N137 photo-couplers
VCC ports be connected with the SCLK ports of 32 AD7177-2 chips simultaneously,
One end of resistance R24 in electronic circuit shown in Fig. 5 b, the VE ports of 6N137 photo-couplers and 6N137 photo-couplers
VCC ports be connected with the DIN ports of 32 AD7177-2 chips simultaneously,
One end of resistance R26 in electronic circuit shown in Fig. 5 c, the VE ports of 6N137 photo-couplers and 6N137 photo-couplers
VCC ports be connected simultaneously and be connected with single-chip microcomputer 2；
Fig. 6 is the circuit diagram of single-chip microcomputer；
Fig. 7 is the circuit diagram of display.
Specific embodiment
Specific embodiment one：Present embodiment is illustrated with reference to Fig. 1, seven and half high accuracy described in present embodiment
Wide-range resistance measuring instrument, it includes：Display 1, single-chip microcomputer 2, photoelectric isolating circuit 3, constant-current source 4, amplifying circuit 5, AD turn
Change 6, stylus 7 of circuit and No. two stylus 8；
The display signal input part for showing signal output part connection display 1 of single-chip microcomputer 2, the filtering signal of single-chip microcomputer 2
The filtering signal output end of the defeated connection photoelectric isolating circuit 3 of input, the digital signal input end connection AD of photoelectric isolating circuit 3 turns
The digital signal output end of circuit 6 is changed, the analog signal of the input end of analog signal connection amplifying circuit 5 of A/D converter circuit 6 is defeated
Go out end, the current controling signal output end of single-chip microcomputer 2 connects the current controling signal input of constant-current source 4, the amplification of single-chip microcomputer 2
Control signal output connects the amplification control signal input of amplifying circuit 5, and the current output terminal of constant-current source 4 connects one simultaneously
The current input terminal and the current input terminal of No. two stylus 8 of number stylus 7, the voltage input end of amplifying circuit 5 connects No. one simultaneously
The voltage output end of the current output terminal of stylus 7 and No. two stylus 8；
Display 1 includes 8 charactrons and hd7279 display driver chips, and hd7279 display driver chips are used to drive 8
Individual numeral method numeral, single-chip microcomputer 2 show signal output part connect simultaneously hd7279 display driver chips CS ports,
CLK ports, DATA ports and KEY ports.
In present embodiment, as shown in figure 1, the size of current exported using Single-chip Controlling constant-current source, while also controlling
The multiplication factor of amplifier, can be according to the suitable constant current source size of measured resistance Automatic Combined and amplifier multiple, syntagmatic
As shown in table 1.Present embodiment produces constant current source and passes through measured resistance using constant-current source, it is only necessary to measure tested electricity
The size of voltage in resistance, in single-chip microcomputer, according to the ratio that resistance is voltage and electric current, you can obtain the resistance size of resistance.I.e.：
Measurement scheme adopts voltammetry, the complicated purpose of simplified measuring system is reached, while number of elements and precision can be reduced slightly.And
Above-mentioned calculating process is known in the art general knowledge, is not utility model point of the present utility model, is not related to the guarantor of utility model
Shield object problem.Present embodiment recognizes the resistance of testee using single-chip microcomputer, and then obtains resistance range gear, without the need for drawing
Enter keyboard system to adjust gear, reach the purpose of further automation.Amplifier is by the magnitude of voltage in the measured resistance for drawing
Send after amplification into A/D converter circuit, send to single-chip microcomputer after Jing analog-to-digital conversion process and filtering, be finally sent to display
Show.In practical application, single-chip microcomputer also controls the mode of operation inside A/D converter circuit by photoelectric isolating circuit 3,
Wave filter mode of operation specially inside control A/D converter circuit, and then the effect of double-smoothing is realized, improve precision.Except
Outside the filtering of each inside parts, in order to improve signal to noise ratio, present embodiment introduces photoelectric isolating circuit 3, concrete to adopt
6N137 chips, it has temperature, electric current and voltage compensating function, the isolation of high input and output, and then reduces A/D module and monolithic
Noise jamming between machine.Display 1 is formed seven and half and is measured using the eight-digit number word of eight charactrons of hd7279 chip drives
The form of value, reduces design cost, and its specific circuit is as shown in Figure 7.Because low resistance measurement belongs to high-acruracy survey, so
Wire internal resistance also must be considered that.For this purpose, present embodiment is as shown in figure 1, constant-current source 4,5, stylus 7 of amplifying circuit and No. two
Four-wire system annexation, four-wire system is adopted to compare for two-wire system, can not be affected by conductor resistance, further between stylus 8
Improve the precision of result measured by present embodiment.
Table 1 measures the combination of electric current and multiplication factor
The measurable range ability of present embodiment is 0.5m Ω to 20M Ω, and display can show seven and half resistances, 2
More than Ω ranges can accomplish the relative error in 15ppm, can accomplish that the technology of ± 0.01% reading ± 5 word will in 2 below Ω
Ask, as shown in table 2.Meanwhile, present embodiment is measured using voltammetry, simpler compared to bridge method, at the same it is simple to operate,
The higher assembler language of execution efficiency can be adopted, it is many less using element.
The test result of table 2
Specific embodiment two：Present embodiment is illustrated with reference to Fig. 2, present embodiment is to specific embodiment one
Seven and half described high-accuracy wide-range resistance measuring instruments are described further, and in present embodiment, constant-current source 4 includes：
SN74LS145N constant-current source decoding chips, relay K1, relay K2, relay K3, relay K4, relay K5, relay
K6, relay K7, LM399 reference voltage source chip, resistance R0, resistance R1, resistance R2, resistance R3, resistance R4, resistance R5, electricity
Resistance R6, resistance R7, resistance R8, resistance R9, resistance R10, Nmos pipe Q1, Pmos pipe Q2, an amplifier and No. two amplifiers；
The A ports of SN74LS145N constant-current source decoding chips, B ports and C-terminal mouth are simultaneously as the current control of constant-current source 4
Signal input part, the drain electrode of Pmos pipe Q2 as constant-current source 4 current output terminal, the C of SN74LS145N constant-current source decoding chips
Port and earth terminal connect power supply ground simultaneously, and the power end of SN74LS145N constant-current source decoding chips connects positive source,
The Y0 ports of SN74LS145N constant-current source decoding chips, Y1 ports, Y2 ports, Y3 ports, Y4 ports, Y5 ports and
Y6 ports are respectively used to control relay K1, relay K2, relay K3, relay K4, relay K5, relay K6 and relay
The coil of device K7 obtains electric or power failure state,
One end of resistance R3, one end of resistance R4, one end of resistance R5, one end of resistance R6, one end of resistance R7, resistance
One end of one end, one end of resistance R9 and resistance R10 of R8 connects positive source simultaneously, the other end of resistance R4, resistance R5
The other end, the other end of resistance R6, the other end of resistance R7, the other end of resistance R8, the other end of resistance R9 and resistance R10's
The other end connects respectively contact one end of relay K1, contact one end of relay K2, contact one end of relay K3, relay
Contact one end of contact one end of K4, contact one end of relay K5, contact one end of relay K6 and relay K7, relay
The contact other end of K1, the contact other end of relay K2, the contact other end of relay K3, relay K4 contact it is another
The contact other end at end, the contact other end of relay K5, the contact other end of relay K6 and relay K7 connects simultaneously
The source electrode of Pmos pipe Q2 and the inverting input of No. two amplifiers, the output end of No. two amplifiers connects the grid of Pmos pipe Q2,
The other end of resistance R3 connects the drain electrode of Nmos pipe Q1 and the normal phase input end of No. two amplifiers, Nmos pipe Q1 simultaneously
Source electrode connect the reverse input end of an amplifier and one end of resistance R0 simultaneously, another termination power ground of resistance R0,
The grid of Nmos pipe Q1 connects the output end of an amplifier, and the positive input of an amplifier connects the one of resistance R1 simultaneously
End and one end of resistance R2, the other end of resistance R1,1 pin of LM399 reference voltage source chips and 3 pin are connecting power supply just simultaneously
Pole, the other end of resistance R2,2 pin of LM399 reference voltage source chips and 4 pin connect power supply ground simultaneously.
In present embodiment, then single-chip microcomputer coding is decoded by SN74LS145N constant-current sources decoding chip, is controlled respectively
The shut-off of 7 relays with it is open-minded, so as to control constant current source size.
Present embodiment can also adopt integrated operational amplifier circuit structure, and the chip that the structure is adopted is ADA4522-2, and this is new
Cake core is that input can reach 0V and rail-to-rail output when a binary channels, zero shift, low noise, low-power consumption, single supply are powered
Amplifier, excellent performance.It is twin-channel to mean namely two integrated transporting dischargings of present embodiment circuit, chip piece can be used
ADA4522-2。
Be divided into 50mA, 5mA, 1mA, 100 μ A, 10 μ A, seven gears of 1 μ A and 0.1 μ A in constant-current source, by Single-chip Controlling after
Electric apparatus coil K1, K2, K3, K4, K5, K6, K7 realize that seven gears are selected.
In the Ω shelves of 20m Ω to 20, the coil of relay K1 turns on its closing of contact, and R4 is 50 Ω, flows through measured resistance
Current value 50MA；In 200 Ω shelves, the coil of relay K2 turns on its closing of contact, and R5 is 500 Ω, flows through measured resistance electricity
Flow valuve 5mA；In 2K Ω shelves, the coil of relay K3 turns on its closing of contact, and R5 is 2.5K Ω, flows through measured resistance current value
1mA；In 20K Ω shelves, the coil of relay K4 turns on its closing of contact, and R5 is 25K Ω, flows through the μ of measured resistance current value 100
A；In 200K Ω shelves, the coil of relay K5 turns on its closing of contact, and R5 is 250K Ω, flows through the μ of measured resistance current value 10
A；In 2M Ω shelves, the coil of relay K6 turns on its closing of contact, and R5 is 2.5M Ω, flows through the μ A of measured resistance current value 1；
During 20M Ω shelves, the coil of relay K7 turns on its closing of contact, and R5 is 2.5M Ω, flows through the μ A of measured resistance current value 0.1.
Specific embodiment three：Present embodiment is illustrated with reference to Fig. 3, present embodiment is to specific embodiment one
Seven and half described high-accuracy wide-range resistance measuring instruments are described further, and in present embodiment, amplifying circuit 5 includes：
SN74LS145N amplifier decoding chips, relay K8, relay K9, relay K10, relay K11, relay K12, relay
Device K13, resistance R11, resistance R12, resistance R13, resistance R14, resistance R15, resistance R16, resistance R17, resistance R18, resistance
R19, resistance R20, No. three amplifiers and No. four amplifiers；
The A ports of SN74LS145N amplifier decoding chips, B ports and C-terminal mouth are simultaneously as the amplification control of amplifying circuit 5
Signal input part processed, contact one end of relay K10, contact one end of relay K11, contact one end of relay K12, relay
Contact one end of device K13 is connected and as the analog signal output of amplifying circuit 5, electricity simultaneously with the output end of No. four amplifiers
One end of R11 and one end of resistance R12 are hindered simultaneously as the current input terminal of amplifying circuit 5,
SN74LS145N amplifier decoding chipsPort,Port,Port,Port,Port and
Port is respectively used to control relay K8, relay K9, relay K10, relay K11, relay K12, the line of relay K13
Enclose electric or power failure state, the C-terminal mouth and earth terminal of SN74LS145N amplifier decoding chips connect power supply ground simultaneously,
The power end connection positive source of SN74LS145N amplifier decoding chips,
The contact other end of the contact other end of relay K10, the contact other end of relay K11 and relay K12 point
One end of one end, one end of resistance R19 and resistance R20 not with resistance R18 is connected, the other end of resistance R18, resistance R19
The contact other end of the other end, the other end of resistance R20, one end of resistance R17 and relay K13 connects No. four amplifiers simultaneously
Positive input, resistance R17 another termination power ground,
The reverse input end of No. four amplifiers connects one end, one end of resistance R14 and No. three amplifiers of resistance R13 simultaneously
Output end, the other end of resistance R13 connects contact one end of relay K8, and one end connection relay K9's of resistance R14 touches
Point one end, the other end of the contact other end of relay K8, the contact other end of relay K9 and resistance R11 connects No. three simultaneously
The positive input of amplifier, the reverse input end of No. three amplifiers connects contact one end, the relay K9 of relay K8 simultaneously
Contact one end and resistance R12 the other end, the contact other end of relay K8 connects one end of resistance R15, relay K9's
The contact other end connects one end of resistance R16, the other end of resistance R15 and another termination power ground of resistance R16.
In present embodiment, then single-chip microcomputer coding is decoded by SN74LS145N amplifiers decoding chip, is controlled respectively
The shut-off of 6 relays with it is open-minded, so as to control amplifier magnification ratio size.
Amplifier module employs two-stage and amplifies 5 passages, is divided into 1,2,20,200 and 2000 times of five gears, there is monolithic
Machine control relay K8, relay K9, relay K10, relay K11, relay K12 and relay K13 realize five multiples
Select.
When multiplication factor is 1 times, the coil of relay K8 turns on two closing of contact, while the line of relay K13
Circle is also switched on its closing of contact.
When multiplication factor is 2 times, the coil of relay K9 turns on two closing of contact, while the line of relay K13
Circle is also switched on its closing of contact.
When multiplication factor is 20 times, the coil of relay K9 turns on two closing of contact, while the line of relay K12
Circle is also switched on its closing of contact.
When multiplication factor is 200 times, the coil of relay K9 turns on two closing of contact, while relay K11
Coil is also switched on its closing of contact.
When multiplication factor is 2000 times, the coil of relay K9 turns on two closing of contact, while relay K10
Coil is also switched on its closing of contact.
Specific embodiment four：Present embodiment is to the seven and half high-accuracy wide-ranges electricity described in specific embodiment one
Resistance measuring instrument is described further, and in present embodiment, A/D converter circuit 6 includes 32 AD7177-2 chips.
A/D converter circuit 6 adopts 32 AD7177-2 chips, is the characteristics of the chip：Fast and flexible, output speed is
5SPS～10kSPS, this characteristic can determine that present embodiment can adjust test speed.Need to reach 7 half in high precision
When, then test speed is relative can slow down, and the chip that present embodiment is adopted can just pass through Single-chip Controlling A/D chip work
Operation mode adjusts test speed.If desired test speed is accelerated, then need to reduce precision to five and half or six and half.
The most fast setup time of this chip is 100 μ s, and most slow setup time is 0.2s, is adapted to various precision.At the same time
The chip also has three kinds of internal digital filter functions, it is also possible to which, according to required precision, through Single-chip Controlling filter patterns, it is
A low noise sound chip, disclosure satisfy that the required precision of 7 half ohmmeters of high accuracy.
In practical application, concrete structure is then defeated as shown in figure 4, by the voltage in measured resistance through enhanced processing
It is sent on 32 AD7177-2 chips, carries out analog-to-digital conversion and draw digital quantity.After Jing single-chip microcomputer exploitation into resistance value, by electricity
Resistance is sent to display module and shows.
Specific embodiment five：Present embodiment is to the seven and half high-accuracy wide-ranges electricity described in specific embodiment four
Resistance measuring instrument is described further, and in present embodiment, photoelectric isolating circuit 3 includes three groups of electronic circuits, and every group of electronic circuit leads to
Cross 6N137 photo-couplers and be filtered isolation.
In present embodiment, as shown in Figure 5：
One end of resistance R22 in electronic circuit shown in Fig. 5 a, the VE ports of 6N137 photo-couplers and 6N137 photo-couplers
VCC ports be connected with the SCLK ports of 32 AD7177-2 chips simultaneously；
One end of resistance R24 in electronic circuit shown in Fig. 5 b, the VE ports of 6N137 photo-couplers and 6N137 photo-couplers
VCC ports be connected with the DIN ports of 32 AD7177-2 chips simultaneously；
One end of resistance R26 in electronic circuit shown in Fig. 5 c, the VE ports of 6N137 photo-couplers and 6N137 photo-couplers
VCC ports be connected simultaneously and be connected with single-chip microcomputer 2.
Specific embodiment six：Present embodiment is to the seven and half high-accuracy wide-ranges electricity described in specific embodiment one
Resistance measuring instrument is described further, and in present embodiment, single-chip microcomputer 2 is W78c516b chips.
In present embodiment, single-chip microcomputer and its peripheral circuit are as shown in Figure 6.
The utility model just can realize a kind of new small resistance measurement instrument through modules, and technical indicator is as follows：
The measurement of 1 resistance, measurement resistance model amount is 0.5m Ω -20M Ω；
DC voltage value between 2 measurement 0-2V；
3 produce constant electric current for 50mA, 5mA, 1mA, 100 μ A, 10 μ A, 1 μ A and 0.1 μ A.
The degree of accuracy of low resistance part is up to ± 0.01% reading ± 5 word, and high resistance portion progress is reached (million in 15ppm
/ mono-), the little design safety of test electric current, only 50mA, 5mA, 1mA, 100 μ A, 10 μ A, 1 μ A and 0.1 μ A, test electric current is steady
Qualitative up to 0.02%/1 minute.
The technical solution of the utility model main points are as follows：
1st, resistance measurement with voltammetry is adopted；
2nd, constant-current source and amplifier adopt novel multi-channel hierarchical approaches, Automatic Combined；
3rd, when constant current source size and amplifier multiple is selected, relay is introduced, is realized certainly by single-chip microcomputer and relay
The identification switching of momentum journey；
4th, using four-wire system measuring resistance；
5th, chip chamber is filtered using photoelectric isolating circuit, reduces noise jamming；
6th, the effective accuracy of 7 half is realized using 32 AD modulus conversion chips；
7th, electric current is little is 50mA, design safety to the maximum for test.
Claims (6)
1. seven and half high-accuracy wide-range resistance measuring instrument, it is characterised in that it includes：Display (1), single-chip microcomputer (2), photoelectricity
Isolation circuit (3), constant-current source (4), amplifying circuit (5), A/D converter circuit (6), a stylus (7) and No. two stylus (8)；
The display signal input part of display signal output part connection display (1) of single-chip microcomputer (2), the filtering letter of single-chip microcomputer (2)
The filtering signal output end of number input connection photoelectric isolating circuit (3), the digital signal input end of photoelectric isolating circuit (3) connects
Connect the digital signal output end of A/D converter circuit (6), input end of analog signal connection amplifying circuit (5) of A/D converter circuit (6)
Analog signal output, single-chip microcomputer (2) current controling signal output end connection constant-current source (4) current controling signal input
End, the amplification control signal input of amplification control signal output connection amplifying circuit (5) of single-chip microcomputer (2), constant-current source (4)
Current output terminal connect the current input terminal of a stylus (7) and the current input terminal of No. two stylus (8), amplifying circuit simultaneously
(5) voltage input end connects the current output terminal of a stylus (7) and the voltage output end of No. two stylus (8) simultaneously；
Display (1) includes 8 charactrons and hd7279 display driver chips, and hd7279 display driver chips are used to drive 8
Numeral method numeral, single-chip microcomputer (2) show signal output part connect simultaneously hd7279 display driver chips CS ports,
CLK ports, DATA ports and KEY ports.
2. seven and half high-accuracy wide-ranges resistance measuring instrument according to claim 1, it is characterised in that constant-current source (4) is wrapped
Include：SN74LS145N constant-current source decoding chips, relay K1, relay K2, relay K3, relay K4, relay K5, relay
Device K6, relay K7, LM399 reference voltage source chip, resistance R0, resistance R1, resistance R2, resistance R3, resistance R4, resistance R5,
Resistance R6, resistance R7, resistance R8, resistance R9, resistance R10, Nmos pipe Q1, Pmos pipe Q2, an amplifier and No. two amplifiers；
The A ports of SN74LS145N constant-current source decoding chips, B ports and C-terminal mouth are believed as the current control of constant-current source (4) simultaneously
Number input, the drain electrode of Pmos pipe Q2 as constant-current source (4) current output terminal, the C of SN74LS145N constant-current source decoding chips
Port and earth terminal connect power supply ground simultaneously, and the power end of SN74LS145N constant-current source decoding chips connects positive source,
The Y0 ports of SN74LS145N constant-current source decoding chips, Y1 ports, Y2 ports, Y3 ports, Y4 ports, Y5 ports and Y6 ends
Mouth is respectively used to control relay K1, relay K2, relay K3, relay K4, relay K5, relay K6 and relay K7
Coil obtain electric or power failure state,
One end of resistance R3, one end of resistance R4, one end of resistance R5, one end of resistance R6, one end of resistance R7, resistance R8
One end of one end, one end of resistance R9 and resistance R10 connects positive source simultaneously, the other end of resistance R4, resistance R5 it is another
End, the other end of resistance R6, the other end of resistance R7, the other end of resistance R8, the other end of resistance R9 and resistance R10 it is another
End respectively connects contact one end of relay K1, contact one end of relay K2, contact one end of relay K3, relay K4
Contact one end of contact one end, contact one end of relay K5, contact one end of relay K6 and relay K7, relay K1's
The contact other end, the contact other end of relay K2, the contact other end of relay K3, the contact other end of relay K4, after
The contact other end of the contact other end of electrical equipment K5, the contact other end of relay K6 and relay K7 connects Pmos pipe Q2 simultaneously
Source electrode and No. two amplifiers inverting input, the output end of No. two amplifiers connects the grid of Pmos pipe Q2,
The other end of resistance R3 connects the drain electrode of Nmos pipe Q1 and the normal phase input end of No. two amplifiers, the source of Nmos pipe Q1 simultaneously
Pole connects the reverse input end of an amplifier and one end of resistance R0, another termination power ground of resistance R0, Nmos pipes simultaneously
The grid of Q1 connects the output end of an amplifier, and the positive input of an amplifier connects one end and the electricity of resistance R1 simultaneously
One end of resistance R2, the other end of resistance R1,1 pin of LM399 reference voltage source chips and 3 pin connect positive source, resistance simultaneously
The other end of R2,2 pin of LM399 reference voltage source chips and 4 pin connect power supply ground simultaneously.
3. seven and half high-accuracy wide-ranges resistance measuring instrument according to claim 1, it is characterised in that amplifying circuit (5)
Including：SN74LS145N amplifier decoding chips, relay K8, relay K9, relay K10, relay K11, relay
K12, relay K13, resistance R11, resistance R12, resistance R13, resistance R14, resistance R15, resistance R16, resistance R17, resistance
R18, resistance R19, resistance R20, No. three amplifiers and No. four amplifiers；
The A ports of SN74LS145N amplifier decoding chips, B ports and C-terminal mouth are controlled as the amplification of amplifying circuit (5) simultaneously
Signal input part, contact one end of relay K10, contact one end of relay K11, contact one end of relay K12, relay
Contact one end of K13 is connected and as the analog signal output of amplifying circuit (5), electricity simultaneously with the output end of No. four amplifiers
One end of R11 and one end of resistance R12 are hindered simultaneously as the current input terminal of amplifying circuit (5),
SN74LS145N amplifier decoding chipsPort,Port,Port,Port,Port andPort
It is respectively used to control relay K8, relay K9, relay K10, relay K11, relay K12, the coil of relay K13 to obtain
Electricity or power failure state, the C-terminal mouth and earth terminal of SN74LS145N amplifier decoding chips connect power supply ground simultaneously, and SN74LS145N is put
The power end connection positive source of big device decoding chip,
The contact other end of the contact other end of relay K10, the contact other end of relay K11 and relay K12 respectively with
One end of resistance R18, one end of resistance R19 are connected with one end of resistance R20, the other end of resistance R18, resistance R19 it is another
The contact other end of end, the other end of resistance R20, one end of resistance R17 and relay K13 is connecting No. four amplifiers just simultaneously
To input, another termination power ground of resistance R17,
The reverse input end of No. four amplifiers connects the defeated of one end of resistance R13, one end of resistance R14 and No. three amplifiers simultaneously
Go out end, the other end of resistance R13 connects contact one end of relay K8, and one end of resistance R14 connects the contact one of relay K9
End, the other end of the contact other end of relay K8, the contact other end of relay K9 and resistance R11 connects No. three amplifications simultaneously
The positive input of device, the reverse input end of No. three amplifiers connects contact one end of relay K8, relay K9 and touches simultaneously
Point one end and the other end of resistance R12, the contact other end of relay K8 connects one end of resistance R15, the contact of relay K9
The other end connects one end of resistance R16, the other end of resistance R15 and another termination power ground of resistance R16.
4. seven and half high-accuracy wide-ranges resistance measuring instrument according to claim 1, it is characterised in that A/D converter circuit
(6) 32 AD7177-2 chips are included.
5. seven and half high-accuracy wide-ranges resistance measuring instrument according to claim 4, it is characterised in that photoelectric isolating circuit
(3) including three groups of electronic circuits, every group of electronic circuit is filtered isolation by 6N137 photo-couplers.
6. seven and half high-accuracy wide-ranges resistance measuring instrument according to claim 1, it is characterised in that single-chip microcomputer (2) is
W78c516b chips.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621089005.7U CN206114777U (en) | 2016-09-28 | 2016-09-28 | Seven and half high accuracy wide -range resistance measurement appearance |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621089005.7U CN206114777U (en) | 2016-09-28 | 2016-09-28 | Seven and half high accuracy wide -range resistance measurement appearance |
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|---|---|
| CN206114777U true CN206114777U (en) | 2017-04-19 |
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ID=58520931
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106990295A (en) * | 2017-05-23 | 2017-07-28 | 江南工业集团有限公司 | A kind of resistance measuring instrument and resistance measurement method |
| CN107015177A (en) * | 2017-06-01 | 2017-08-04 | 北京市京核鑫隆科技中心 | Magnetic declination dipmeter automatic range switching circuit |
-
2016
- 2016-09-28 CN CN201621089005.7U patent/CN206114777U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106990295A (en) * | 2017-05-23 | 2017-07-28 | 江南工业集团有限公司 | A kind of resistance measuring instrument and resistance measurement method |
| CN107015177A (en) * | 2017-06-01 | 2017-08-04 | 北京市京核鑫隆科技中心 | Magnetic declination dipmeter automatic range switching circuit |
| CN107015177B (en) * | 2017-06-01 | 2023-08-01 | 北京市京核鑫隆科技中心 | Automatic range switching circuit of declination inclinometer |
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Granted publication date: 20170419 Termination date: 20170928 |