CN214041542U - Constant current circuit for direct current resistance tester - Google Patents
Constant current circuit for direct current resistance tester Download PDFInfo
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- CN214041542U CN214041542U CN202021885144.7U CN202021885144U CN214041542U CN 214041542 U CN214041542 U CN 214041542U CN 202021885144 U CN202021885144 U CN 202021885144U CN 214041542 U CN214041542 U CN 214041542U
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- resistor
- resistance
- operational amplifier
- power field
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Abstract
The utility model discloses a constant current circuit for a direct current resistance tester, which comprises an operational amplifier UB, a load resistor R, a sampling resistor R1, a high-precision resistor Z and a high-power field effect transistor Q; wherein the syntropy input of operational amplifier UB connects the reference voltage Vi of input, operational amplifier UB 'S output is connected with load resistance R' S one end, input voltage VCC is connected to sampling resistance R1 'S one end, the drain electrode D of high-power field effect transistor is connected to sampling resistance R1' S the other end, high-power field effect transistor 'S source electrode S is connected with the one end of being surveyed resistance DUT, the other end of being surveyed resistance DUT respectively with high accuracy resistance Z' S one end, operational amplifier UB 'S reverse input end is connected, high accuracy resistance Z' S other end ground connection, the utility model discloses test speed is fast, the test result precision is high, the testing process is stable, can control the not electric current of equidimension through control reference voltage, avoids some being surveyed the product because generate heat through the electric current and lead to the problem of resistance change.
Description
Technical Field
The utility model relates to a constant current source circuit field especially relates to a constant current circuit for direct current resistance tester.
Background
In modern industrial production, various resistors play an increasingly important role, and the resistors of various products need to be qualified to be put into production application, such as coils, inductors, transformers, fuses, relays and the like, so that the resistance detection equipment is produced at the right moment.
The resistance tester comprises a grounding resistance tester, an insulation resistance tester, a direct current resistance tester, a surface resistance tester and a loop resistance tester. But some products to be tested can generate heat due to passing current to cause the change of resistance value, so that the test result is inaccurate.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that can arouse that the resistance changes because of the electric current passes through to traditional test method in the background art and lead to this kind of problem that the test result is inaccurate provides a constant current circuit for direct current resistance tester.
The utility model discloses a solve above-mentioned technical problem and adopt following technical scheme:
a constant current circuit for a direct current resistance tester comprises an operational amplifier UB, a load resistor R, a sampling resistor R1, a high-precision resistor Z, a high-power field-effect tube Q and a tested resistor DUT;
wherein, the same-direction input end of the operational amplifier UB is connected with the input reference voltage Vi,
the output of the operational amplifier UB is connected to one end of the load resistor R,
one end of the sampling resistor R1 is connected to the input voltage VCC,
the other end of the sampling resistor R1 is connected with the drain D of the high-power field effect transistor,
the source S of the high-power field effect transistor is connected with one end of a tested resistor DUT,
the other end of the tested resistor DUT is respectively connected with one end of the high-precision resistor Z and the inverted input end of the operational amplifier UB,
the other end of the high-precision resistor Z is grounded.
As a further preferred aspect of the present invention, the resistance of the load resistor R is 1k Ω.
As a further preferred aspect of the present invention, the sampling resistor R1 has a resistance of 2k Ω, which is used for a constant current circuit of a dc resistance tester.
As a further preferred aspect of the present invention, the resistance of the high-precision resistor Z is 477 Ω in a constant current circuit for a dc resistance tester.
The utility model adopts the above technical scheme to compare with prior art, have following technological effect:
1. the utility model has the advantages of fast testing speed, high precision of testing result and stable testing process;
2. the utility model discloses can control the not electric current of equidimension through control reference voltage, avoid some to be surveyed the product because generate heat through the electric current and lead to the problem that the resistance changes.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
As shown in fig. 1, a constant current circuit for a dc resistance tester comprises an operational amplifier UB, a load resistor R, a sampling resistor R1, a high precision resistor Z, a high power field effect transistor Q, and a tested resistor DUT;
wherein, the same-direction input end of the operational amplifier UB is connected with the input reference voltage Vi,
the output of the operational amplifier UB is connected to one end of the load resistor R,
one end of the sampling resistor R1 is connected to the input voltage VCC,
the other end of the sampling resistor R1 is connected with the drain D of the high-power field effect transistor,
the source S of the high-power field effect transistor is connected with one end of a tested resistor DUT,
the other end of the tested resistor DUT is respectively connected with one end of the high-precision resistor Z and the inverted input end of the operational amplifier UB,
the other end of the high-precision resistor Z is grounded.
The resistance value of the load resistor R is 1k omega.
The resistance of the sampling resistor R1 is 2k omega.
The resistance value of the high-precision resistor Z is 477 omega.
The input impedance of the operational amplifier UB is extremely large, almost no current passes through, the grid current of the field-effect tube is very small and can be ignored, and the field-effect tube Q is adopted to be easier for voltage linear control of current. The current through R1 for the measured resistor DUT and the high-precision sampling resistor Z can be considered to be the same I.
According to the characteristics of the operational amplifier, "virtual short" and "virtual break", the voltages at the two inputs are equal, i.e., V + ═ V- ═ Vi, so that the current I ═ Vi/Z, according to ohm's law: r ═ U/I, the specific resistance value can be obtained as long as the voltage drop of the measured resistor is known, and the voltage drop of the measured resistor DUT can be obtained by sampling: V2-V1, so the resistance R of the tested resistor DUT is Z (V2-V1)/Vi.
The points to be finally explained are: first, in the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounted," "connected," and "connected" should be understood broadly, and may be a mechanical connection or an electrical connection, or a communication between two elements, and may be a direct connection, and "upper," "lower," "left," and "right" are only used to indicate a relative positional relationship, and when the absolute position of the object to be described is changed, the relative positional relationship may be changed;
secondly, the method comprises the following steps: in the drawings of the disclosed embodiments of the present invention, only the structures related to the disclosed embodiments are referred to, and other structures can refer to the common design, and under the condition of no conflict, the same embodiment and different embodiments of the present invention can be combined with each other;
and finally: the above description is only for the preferred embodiment of the present invention and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. A constant current circuit for a direct current resistance tester, characterized in that: the device comprises an operational amplifier UB, a load resistor R, a sampling resistor R1, a high-precision resistor Z, a high-power field-effect tube Q and a tested resistor DUT;
wherein, the same-direction input end of the operational amplifier UB is connected with the input reference voltage Vi,
the output of the operational amplifier UB is connected to one end of the load resistor R,
one end of the sampling resistor R1 is connected to the input voltage VCC,
the other end of the sampling resistor R1 is connected with the drain D of the high-power field effect transistor,
the source S of the high-power field effect transistor is connected with one end of a tested resistor DUT,
the other end of the tested resistor DUT is respectively connected with one end of the high-precision resistor Z and the inverted input end of the operational amplifier UB, and the other end of the high-precision resistor Z is grounded.
2. A constant current circuit for a direct current resistance tester according to claim 1, wherein: the resistance value of the load resistor R is 1k omega.
3. A constant current circuit for a direct current resistance tester according to claim 1, wherein: the resistance of the sampling resistor R1 is 2k omega.
4. A constant current circuit for a direct current resistance tester according to claim 1, wherein: the resistance value of the high-precision resistor Z is 477 omega.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021885144.7U CN214041542U (en) | 2020-09-01 | 2020-09-01 | Constant current circuit for direct current resistance tester |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021885144.7U CN214041542U (en) | 2020-09-01 | 2020-09-01 | Constant current circuit for direct current resistance tester |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214041542U true CN214041542U (en) | 2021-08-24 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021885144.7U Expired - Fee Related CN214041542U (en) | 2020-09-01 | 2020-09-01 | Constant current circuit for direct current resistance tester |
Country Status (1)
| Country | Link |
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| CN (1) | CN214041542U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115580000A (en) * | 2022-12-06 | 2023-01-06 | 苏州贝克微电子股份有限公司 | Constant current power supply circuit |
-
2020
- 2020-09-01 CN CN202021885144.7U patent/CN214041542U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115580000A (en) * | 2022-12-06 | 2023-01-06 | 苏州贝克微电子股份有限公司 | Constant current power supply circuit |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210824 |
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| CF01 | Termination of patent right due to non-payment of annual fee |