CN204516532U - Programme control precision resistance box - Google Patents
Programme control precision resistance box Download PDFInfo
- Publication number
- CN204516532U CN204516532U CN201520224499.4U CN201520224499U CN204516532U CN 204516532 U CN204516532 U CN 204516532U CN 201520224499 U CN201520224499 U CN 201520224499U CN 204516532 U CN204516532 U CN 204516532U
- Authority
- CN
- China
- Prior art keywords
- converter
- output
- operational amplifier
- resistance
- current sampling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The utility model relates to a kind of programme control precision resistance box, comprises controller, D/A converter, current sampling circuit and operational amplifier; The digital input port Di of the output connection D/A converter of described controller holds; The output of described current sampling circuit is held with the Vref of D/A converter and is connected; The voltage output end Vout end of described D/A converter is held with "+" of operational amplifier and is connected; The output of operational amplifier is held with "-" and is connected; A load is connected between the output of operational amplifier and the output of current sampling circuit.The utility model circuit is simple, and without the need to multiple mechanical switch and precision resistance, production cost is extremely low; Only need use the current sampling resistor that high-accuracy, simulate a resistance by controlling D/A converter, this resistance range is wide, and precision is high; As adopted multiplying-type D/A converter, may be used for alternating current-direct current occasion; Adopt programmed control method, convenient and computer connects and composes automatization test system.
Description
Technical field
The utility model relates to a kind of programme control precision resistance box, utilizes D/A converter and operational amplifier and controller to complete the control of precision resistance.
Background technology
Resistance box is widely used in the debugging of circuit with test.At present, the resistance box of use is by tens precision resistances through suitable connection, and recycling multidigit rotary switch carrys out the resistance value needed for selection circuit; Also have and adopt several relays of Single-chip Controlling to replace above-mentioned multidigit rotary switch to realize so-called program-controlled resistor case, these resistance boxes are because have employed mechanical switch or relay, after Long-Time Service, its contact can wear and aging cause contact resistance to increase, thus the precision of resistance box is reduced greatly; Make the resistance that high performance resistance box needs to use a lot of high-accuracy, low-temperature coefficient in addition, these resistance are expensive, draw materials not easily.
Summary of the invention
The technical problems to be solved in the utility model is: propose a kind of programme control precision resistance box.
The technical scheme that the utility model adopts is: a kind of programme control precision resistance box, comprises controller, D/A converter, current sampling circuit and operational amplifier; The digital input port Di of the output connection D/A converter of described controller holds; The output of described current sampling circuit is held with the Vref of D/A converter and is connected; The voltage output end Vout end of described D/A converter is held with "+" of operational amplifier and is connected; The output of described operational amplifier is held with "-" and is connected; A load is connected between the output of described operational amplifier and the output of current sampling circuit.
The beneficial effects of the utility model are: 1, circuit is simple, and without the need to multiple mechanical switch and precision resistance, production cost is extremely low; 2, the utility model only need use a high-accuracy current sampling resistor, and simulate a resistance by controlling D/A converter, this resistance range is wide, and precision is high; 3, as adopted multiplying-type D/A converter, this resistance box may be used for alternating current-direct current occasion; 4, adopt programmed control method, convenient and computer connects and composes automatization test system.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the utility model is further illustrated.
Fig. 1 is structural representation of the present utility model;
In figure: 1, controller; 2, D/A converter; 3, current sampling circuit; 4, operational amplifier.
Fig. 2 is principle key diagram of the present utility model.
Embodiment
With preferred embodiment, the utility model is described in further detail by reference to the accompanying drawings now.These accompanying drawings are the schematic diagram of simplification, only basic structure of the present utility model are described in a schematic way, and therefore it only shows the formation relevant with the utility model.
The framework of a kind of programme control precision resistance box as shown in Figure 1, comprises four parts such as controller 1, D/A converter 2, current sample 3 and operational amplifier 4.Described programme control precision resistance box, first according to the resistance value of user's setting, the digital input port Di being calculated corresponding digital quantity feeding D/A converter 2 by controller 1 holds, the output of current sample 3 is held with the Vref of D/A converter 2 and is connected, and the voltage output end Vout of D/A converter 2 holds with "+" of operational amplifier 4 and is connected; The output of operational amplifier 4 is held with "-" and is connected; Above-mentioned 2 road signals are through the process of operational amplifier 4, and make to simulate an ohmic load at circuit RX+ and RX-two ends, the electric current that this load both end voltage flows through with it is proportional, realize permanent resistance and control.
Principle key diagram described in the utility model is as shown in Figure 2: in the present embodiment, and this circuit is primarily of controller U1, D/A converter U2, sampling resistor Rs, current sample amplifier A1 and operational amplifier A 2 etc. 5 part composition.
If the voltage that external circuit is applied to this fictitious load two ends is Us, the load current flowing through circuit is Is.
According to circuit connecting relation, being not difficult to obtain the voltage V1 that operational amplifier A 2 "+" holds is following expression:
Wherein: wherein: Is is the load current flowing through circuit; Rs is current sampling resistor value; Dx is the digital quantity that controller exports; N is the control figure place of D/A converter U2.
Be not difficult to obtain following relationship according to the characteristic of operational amplifier:
V2＝Us
Wherein: Us is the voltage that external circuit is applied to this fictitious load two ends.
Because circuit has profound and negative feedbck, V2 should be equaled by the known V1 of the characteristic of operational amplifier, that is:
The resistance Rx that can obtain the simulation of these circuit two ends further meets following expression:
Wherein: Us is the voltage being applied to this fictitious load two ends; Is is the load current flowing through circuit; Dx is the digital quantity that controller U1 exports; N is the control figure place of D/A converter U2; RS is sampling resistor resistance.
Obviously, have benefited from the ingehious design of circuit, by using a high-precision sampling resistor Rs, coordinate the control to D/A converter, just can simulate different resistance, and this artifical resistance having identical high precision performance with sampling resistor Rs.As selected different sampling resistor Rs by controller coordinated again, this circuit just can simulate the resistance value obtaining machine with wide range, and as adopted multiplying-type D/A converter, this circuit not only may be used for DC circuit, is applicable to alternating current circuit too.Therefore, the utility model scheme can realize the function of programme control precision resistance box completely.
The just embodiment of the present utility model described in above specification, various illustrating is not construed as limiting flesh and blood of the present utility model, person of an ordinary skill in the technical field after having read specification can to before described embodiment make an amendment or be out of shape, and do not deviate from essence and the scope of utility model.
Claims (1)
1. a programme control precision resistance box, is characterized in that: comprise controller, D/A converter, current sampling circuit and operational amplifier; The digital input port Di of the output connection D/A converter of described controller holds; The output of described current sampling circuit is held with the Vref of D/A converter and is connected; The voltage output end Vout end of described D/A converter is held with "+" of operational amplifier and is connected; The output of described operational amplifier is held with "-" and is connected; A load is connected between the output of described operational amplifier and the output of current sampling circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520224499.4U CN204516532U (en) | 2015-04-14 | 2015-04-14 | Programme control precision resistance box |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520224499.4U CN204516532U (en) | 2015-04-14 | 2015-04-14 | Programme control precision resistance box |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204516532U true CN204516532U (en) | 2015-07-29 |
Family
ID=53714480
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201520224499.4U Expired - Fee Related CN204516532U (en) | 2015-04-14 | 2015-04-14 | Programme control precision resistance box |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN204516532U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104810122A (en) * | 2015-04-14 | 2015-07-29 | 常州信息职业技术学院 | Programmable control precision resistor box |
| CN104880963A (en) * | 2014-10-27 | 2015-09-02 | 上海葩星信息科技有限公司 | Resistor simulator |
-
2015
- 2015-04-14 CN CN201520224499.4U patent/CN204516532U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104880963A (en) * | 2014-10-27 | 2015-09-02 | 上海葩星信息科技有限公司 | Resistor simulator |
| CN104810122A (en) * | 2015-04-14 | 2015-07-29 | 常州信息职业技术学院 | Programmable control precision resistor box |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN204515009U (en) | A kind of super low-power consumption battery voltage detection circuit | |
| CN205015401U (en) | Electric automobile insulation resistance detection circuitry | |
| CN104330640A (en) | Large scale and high accuracy RLC (radio link control) measurement device and method | |
| CN204516532U (en) | Programme control precision resistance box | |
| CN203444012U (en) | High accuracy and rapid speed measurement circuit of wide range current in power system | |
| CN104460462A (en) | Sampling circuit compatible with unipolar and bipolar analog signals | |
| CN202582775U (en) | Temperature measuring circuit | |
| CN102707128B (en) | A kind of ac signal acquisition circuit based on microcontroller and method | |
| CN104914781A (en) | Program controlled AC-DC resistance box | |
| CN102809443A (en) | Method and circuit for measuring temperature | |
| CN204650239U (en) | Program control alternating current-direct current resistance box | |
| CN207976786U (en) | Controllable voltage constant current source module | |
| CN202018478U (en) | Wide-range electric energy metering device for fluctuating load | |
| CN104810122A (en) | Programmable control precision resistor box | |
| CN201788222U (en) | AC-DC (alternating current-direct current) compatible isolated voltage sampling circuit | |
| CN106685376A (en) | Fractional order inductive circuit | |
| CN203800895U (en) | Offset current parameter programmable type operational amplifier | |
| CN101887081A (en) | Bridge zero adjustment circuit | |
| CN203643498U (en) | Voltage sampling circuit of double supply change-over switch | |
| CN207216393U (en) | The current measurement circuit and programmable logic controller (PLC) of programmable logic controller (PLC) | |
| CN202041577U (en) | Current sampling circuit of servo motor | |
| CN105510654A (en) | Constant current output circuit for eliminating influence of switch conduction resistance on output current | |
| CN207704217U (en) | A kind of prolongable signal collecting device | |
| CN203396931U (en) | Three-terminal analog resistance circuit used for simulating high-resistance standard resistor | |
| CN201697970U (en) | Bridge zero regulation circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150729 Termination date: 20180414 |