CN85201419U - Multifunctional on-line circuit tester - Google Patents
Multifunctional on-line circuit tester Download PDFInfo
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- CN85201419U CN85201419U CN 85201419 CN85201419U CN85201419U CN 85201419 U CN85201419 U CN 85201419U CN 85201419 CN85201419 CN 85201419 CN 85201419 U CN85201419 U CN 85201419U CN 85201419 U CN85201419 U CN 85201419U
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Abstract
The utility model relates to a multifunctional online circuit tester. The back of the operational amplifier [5] of the multimeter of the abroad Weston foreign company is connected with a bidirectional current driver [18] in series. The back of a measurement amplifier [7] is connected with an alternating current and direct current converter [19]. A meter shell is additionally provided with an alternating current and direct current conversion switch [13] which measures the current value of the online alternating current. In addition, the utility model is additionally provided with an independent constant current source millivolt generator which is adjustable and has indication, an alarm circuit, a switch which is correspondingly arranged on the meter shell, an adjusting knob, etc., which causes the utility model to test the electric fault position in a printed circuit board and an automation device.
Description
The utility model belongs to the testing apparatus of electrical property and fault in the electric measuring instrument, specifically: relate to a kind of multi-functional online circuit detector.
The on-line testing technology is a kind of measuring technology that grows up recent years.When detecting component parameters on the printed circuit board (PCB) and various electrical quantity, need weld element get off to prevent parallel effect in the past; Need cut off circuit with the series current table when detecting electric current.Adopt now the on-line testing technology on printed circuit board (PCB), directly to record component parameters, also can be on printed circuit board (PCB) record the current value that flow through or other electrical quantity etc. with test pencil contact circuit-under-test with test pencil.Obviously, this measuring technology not only convenient but also not fragile printed circuit board (PCB) and electrical equipment, more automatic test lays the foundation.
External Weston corporate system is produced a kind of multimeter that is used for the printed circuit board (PCB) on-line testing, and has made introduction (CANADIAN CONTROLS ﹠amp in " Canada's control and instrument " magazine; LNSTRUMENTATION June 1974.P14-15).This multimeter adopts current feedback method, so just can be under the situation of not cutting off circuit usefulness also linked method record DC current values in the conductor.The used amplifier of this multimeter is an operational amplifier, has high enlargement factor, high cmrr and current drives source.During measurement, earlier record the voltage drop of electric current in conductor with test pencil I and II, feedback current of operational amplifier output this moment is in order to offset tested electric current, and the voltage drop that this feedback current forms on the resistance R on the backfeed loop is amplified by measuring amplifier, and the driving ammeter demonstrates current value.In addition,, provide a full wave bridge type circuit behind the measuring amplifier, and can be surveyed the positive-negative polarity of voltage to demonstrate by two light emitting diodes of polarity comparator drives of back in order to record the combined-voltage value.On the watchcase of this multimeter, an ammeter is arranged, it can indicate current value respectively, magnitude of voltage, resistance value etc.Also has current switch on the watchcase, voltage switch, resistance switch, zeroing switch and a range switch.In this range switch, current gear is direct current, divides 3 milliamperes, and 10 milliamperes, 30 milliamperes, 100 milliamperes and 300 milliamperes.Its voltage gear divides eight retainings, and measurement range is from 0.1 volt to 300 volts.In addition, power block divides seven retainings, measurement range from 1 ohm to 10
6Ohm.
But the multimeter that uses Weston company to make can't be determined the location of short circuit of printed circuit board (PCB) or other electric device with the method for on-line testing.As everyone knows, in the etching or welding process of printed circuit board (PCB), because the imperfection of technology, article two, may have filament between the Copper Foil of P.e.c. links to each other, naked eyes are difficult to find, if owing to the component wear on the printed circuit board (PCB) causes the then more difficult discovery of short circuit, adopted the low-resistance table look-up in the past, effect is bad.
Secondly, DC current (0-10mA or 4-20mA) is often adopted in the signal transmission between automation equipment.For example, the millivolt signal process DDZ series transducing unit from sensor output becomes dc current signal, and then carries out ratio, differential, and integral operation, its operation result with DC current input topworks, makes its action again.But the multimeter of Weston company can only carry out general on-line testing to the position of breaking down, can not give the variable normalized current of parts input or the millivolt signal that break down, therefore also just can't measure the actual working state of trouble unit, make troubles for detection and maintenance.
Once more, in the circuit theory diagrams that provided in the document of the multimeter of the Weston company of introducing from above, operational amplifier wherein is a direct current amplifier, the bi-directional drive ability that whether has alternating current to what, be not described in the literary composition, and the current gear of given multimeter has only zero frequency span in the literary composition.Situation about introducing from document, this multimeter can only the test cross dc voltage values, ohmic value and on-line direct current current value, but can not survey the online exchange current value.From similar instrument or other document that uses at present, there is not to find to possess the multimeter of this function both at home and abroad yet.But on-line testing alternating current flow valuve all is the problem that needs solution in industry and scientific research.
Therefore, task of the present utility model is exactly in order to design a kind of multi-functional measuring instrument that is used for the online circuit test that can solve above-mentioned three aspect problems simultaneously, to overcome the deficiency of original similar instrument.That is to say that the purpose of this utility model is at first will make originally can be used to the multimeter that printed circuit board (PCB) carries out online circuit test to detect and judge location of short circuit in the printed circuit board (PCB); Secondly, this class multimeter can be used for the duty of test automation device and find abort situation, particularly make it applicable to the chemical industry scene, secondly be to make it be used in the test of the alternating current flow valuve in the line circuit again.
Task of the present utility model realizes by following method, promptly increased independently constant current source and millivolt signal generator on the electronic circuit in the multimeter of Weston company and original electronic circuit has also been done some important improvement.Multifunctional on-line circuit tester provided by the utility model has specifically increased the circuit and the parts of following four aspects than former multimeter.
The first, in the multimeter of Weston company, increase by one and the disjunct independent constant-current source circuit of primary circuit, on the multimeter watchcase, increase a constant current source switch.The method that combines by the on-line testing circuit in this constant current source and the former multimeter is judged the location of short circuit of printed circuit board (PCB), promptly between two circuit of tested printed circuit board (PCB), insert constant current source, measure then between these two circuit in line current, if can test out, illustrate to have short circuit between the two in line current.Otherwise, just do not have short circuit.
Also set up a warning circuit in this external original circuit, and in watchcase, increased a microphone device or on watchcase, increased a luminescent device, when short-circuit condition occurring, can in time remind the testing staff with box lunch.
Second, above-mentioned constant current source is made an adjustable constant current source that indication is arranged, increase simultaneously an adjustable millivolt generator circuit that indication is arranged that has nothing to do with primary circuit again, the numerical value of constant current source and millivolt generator can be regulated turn-knob by the potentiometer of setting up on the multimeter watchcase respectively and regulate.Simultaneously, increase a millivolt generator switch again.The indication electric meter of constant current source or millivolt generator adopts original ammeter on the watchcase.Whether like this, when automation equipment breaks down, just can utilize this detector, inserting one in the operation circuit before topworks adjustablely has the constant current source of indication controlled to observe topworks; Whether or it is normal to observe transducing unit work to insert an adjustable millivolt generator that indication is arranged in the incoming line before transducing unit; Also can whether normal to observe its output current value by on-line testing to the outlet line of arithmetical unit; This measuring instrument adopts powered battery in addition.So just solved automation equipment, especially each automation equipment at chemical industry scene has been calibrated and got rid of the problem of electric fault.
The 3rd, change the operational amplifier in the multimeter of above-mentioned Weston company into the low source of broadband shift amplifier, and behind operational amplifier output terminal bidirectional current driver of serial connection, between measuring amplifier output terminal and DC meter, be connected in series an AC switch and AC/DC changeover switch again.This AC-DC conversion switch is contained on the watchcase of multimeter.
The 4th, because of the feed circuit of circuit in the multimeter of original Weston company are to adopt AC-powered, and then become direct current by rectification circuit wherein.But as when will original multimeter using the chemical industry scene, because the chemical industry scene does not often have AC outlet and uses inconvenience, so the utility model also can adopt powered battery, and increased a DC to DC converter in the line and make it and to provide the required voltage value to circuit.
The utility model has the advantages that significantly,, overcome the some shortcomings part, increased new function, make it when being used for determining the location of short circuit of printed circuit board (PCB) by to the multimeter of original Weston company and the improvement of similar instrument, convenient, rapidly, accurately; When being used to detect the electric fault of automation equipment, can seek out of order position rapidly, particularly be applicable to the chemical industry on-the-spot test, this measuring instrument has remedied the defective that original similar instrument can not be carried out alternating current flow valuve measurement in the online circuit simultaneously.In a word, can make the on-line testing technology in industrial or agricultural and scientific research, obtain actual widely the use by this measuring instrument.
The drawing explanation of accompanying drawing
Fig. 1, circuit working principle schematic of the present utility model;
Fig. 2, battery feed circuit synoptic diagram of the present utility model;
Fig. 3, the watchcase planar structure synoptic diagram of an embodiment of the present utility model;
Fig. 4, an operational instances synoptic diagram of detection printed circuit board (PCB) short circuit;
Fig. 5, an operational instances synoptic diagram of detection automation equipment electric fault;
Provide watchcase planar structure and operational instances thereof in circuit working principle of the present utility model and the specific embodiment below with reference to accompanying drawing, and provide details of the present utility model by these descriptions.
Before beginning to narrate the circuit working principle, need to prove, in patent of invention instructions of submitting to simultaneously with this utility model and accompanying drawing, done fully openly can supply public's reference about the details inventor of wherein involved electronic circuit.Moreover the introduction about this part content has exceeded scope of the present utility model.
Referring to Fig. 1, following circuit working schematic diagram of the present utility model is the circuit theory diagrams that the electronic circuit in the multimeter of original Weston company and parts are combined with electronic circuit that increases newly and parts.Wherein the measuring principle of online circuit is such: when measuring DC current, record the voltage drop of electric current in unit under test with the test pencil I (3) and the II (4) that are connected on the electric current jack (1,2) earlier, at this moment, feedback current of operational amplifier (5) output is in order to offset tested electric current, and feedback current forms voltage drop on the resistance R on the backfeed loop 2; Closed path switch (6a), this voltage drop are amplified by measuring amplifier (7), pass through the voltage table that current switch (6b), (6c) make the current drives after the amplification be made up of R1 and ammeter (8) again and demonstrate the DC current values reading.When measuring combined-voltage, utilize voltage jointing holes (9,10) that the voltage of unit under test is inserted, sealing voltage switch (11a), the voltage of input is by attenuator (12), its attenuation coefficient is determined by range switch (not drawing among the figure), (connect during interchange and exchange shelves by AC-DC conversion switch (13) again behind this voltage process measuring amplifier (7), connect zero frequency span during direct current) sealing voltage switch (11b) with, (11c), the voltage table that the driven after the amplification is made up of R1 and ammeter (8) demonstrates the magnitude of voltage reading.When measuring resistance, utilize resistance jack (14,15) that the resistance of unit under test is inserted, closed resistance switch (16a), the resistance that inserts becomes DC voltage by resistance convertor (17) and adds to measuring amplifier (7), behind the zero frequency span of the voltage of its output through AC-DC conversion switch (13), closed resistance switch (16b), (16c) again, the voltage table that makes the voltage after this amplification promote to be made up of R1 and ammeter (8) demonstrates the ohmic value reading.
If survey the alternating current flow valuve of unit under test, because increased a bidirectional current driver (18) behind the operational amplifier in the circuit of above-mentioned measurement DC current values (5), and after the output of measuring amplifier (7), this output current is inserted ac-dc converter circuit (19) by AC-DC conversion switch (13), after making it to be converted to DC current, the voltage table of being made up of resistance R 1 and ammeter (8) demonstrates the D. C. value reading again.
A zeroing switch (20) and zero potentiometer Rp1 are arranged in above-mentioned operational amplifier (5), and the offset voltage that can make operational amplifier is zero.
Determine the location of short circuit of printed circuit board (PCB) or other electric device for the method that will utilize on-line testing, independently a constant-current source circuit (21) and a constant current source switch (22) have been increased in this detector, and constant current source is received on the unit under test by constant current source jack (23,24), in order to make the constant current source scalable and indication to be arranged, after being connected on the potentiometer Rp3 adjusting on the constant-current source circuit, process resistance R 3 and constant current source switch (22) can demonstrate the constant current value reading after inserting ammeter (8) during output current.
Can remind operating personnel when short circuit occurring in order to make, behind measuring amplifier (7), to insert warning circuit (26) through the current signal after the measuring amplifier amplification and send indication by closed alarm switch (25) by sounding and/or luminescent device (27), this warning circuit is the sound telegraph circuit of a continous way, also can be a sound newspaper and/or light telegraph circuit.
In the time will determining electric fault in the instrument and meter for automation with the method for on-line testing, increased an independent millivolt generator circuit (28) and millivolt generator switch (29) in this detector, and millivolt signal has been received on the unit under test by millivolt generator jack (30,31).Can be in harmonious proportion indication on the millivolt generator circuit in order to make, after being connected on the potentiometer Rp2 adjusting on the millivolt generator circuit, after closed millivolt generator switch (29a) makes the zero frequency span of millivolt signal through measuring amplifier (7) and AC-DC conversion switch (13), closed again millivolt generator switch (29b), (29c), the voltage table that the millivolt signal after the amplification is made up of resistance R 1 and table (8) demonstrates a millivolt reading.
Referring to Fig. 2, the utility model can adopt AC/DC circuit or powered battery.Battery powered principle is: a Battery pack (32) is housed in the watchcase of this table, and this battery can adopt dry cell or solar cell, perhaps adopts a group storage battery.The magnitude of voltage of battery is 6V, and battery becomes one group of positive-negative power and another group positive supply by DC/DC transducer (33).These two groups of power supplys are insulated from each other.The magnitude of voltage of positive-negative power becomes 12V, and it follows the A point for anodal, B point ground connection, and the C point is a negative pole.This positive-negative power is for surveying online alternating current-direct current value; Magnitude of voltage, the circuit of resistance value and millivolt generator uses.The voltage of another group positive supply is 27V, and it follows the D point for anodal, E point ground connection; This positive supply uses for constant-current source circuit.Be noted that the earth point mutually insulated that B point and E are ordered.Owing to adopt powered battery, make this instrument easy to carry, be applicable to the test at chemical industry scene.
Referring to Fig. 3, the planar structure of an embodiment of watchcase structure of the present utility model is such: it the multimeter of original Weston company ex hoc genus anne increased some new functional parts on the shell of instrument.Generally comprise following parts on the watchcase of original instrument:
A pair of and electric current jack that links to each other in the line current value metering circuit (1,2) and a pair of measurement test pencil that links to each other with this jack (3,4), if every measurement test pencil adopts two mutual on the line disjunct probes (3a, 3b) and (3a, 4b) simultaneously, measurement effect is better, a current switch (6) that is used to be controlled at the line current metering circuit;
The a pair of voltage jack that links to each other with combined-voltage value metering circuit (9,10) and a voltage switch (11) that is used to control combined-voltage value metering circuit;
The a pair of resistance jack that links to each other with the resistance measurement circuit (14,15) and a resistance switch (16) that is used for controlling resistance value metering circuit;
The a pair of range switch (34) that is used for Control current value, magnitude of voltage, resistance measurement scope;
A zeroing switch (20) and a zero potentiometer turn-knob (35) that is used to regulate operational amplifier;
An ammeter (8) that is used to show the current value of surveying, magnitude of voltage, resistance value.
The parts that increase on the utility model watchcase comprise:
A constant current source jack that links to each other with independent constant-current source circuit (23,24) and a constant current source switch (22) that is used to control constant-current source circuit.This constant current source does not link to each other with electronic circuit in above-mentioned original instrument, because the constant current source in the present embodiment also can be made an adjustable constant current source that indication is arranged, so in this constant-current source circuit, can increase a potentiometer, and on watchcase, increase a constant current source adjusting knob (36), and demonstrate the constant current value of output by original ammeter (8).After having been made above-mentioned adjustment, circuit and parts just can utilize this instrument to survey location of short circuit in printed circuit board (PCB) or other electroprobe device.In order when being short-circuited, to remind operating personnel, increased a sounding and/or a luminescent device that links to each other with the warning circuit that increases at watchcase, this microphone device can also be a loudspeaker (37), also can be a bulb or light emitting diode (38), on watchcase, also increase a switch (25) that is used to control warning circuit.
In order to make the electric fault in this table energy test automation device, in watchcase, increased the millivolt generator jack (30,31) that millivolt generator circuit a pair of and that gauge internal increases links to each other again; Because this millivolt generator circuit is the millivolt generator that can regulate and have indication, regulate turn-knob (39) so also increased a millivolt generator that is used for the potentiometer of regulating circuit on the watchcase, increase a millivolt switch (29) in addition, and show the millivolt value of output by original ammeter (8).
In order to make this instrument on watchcase, also increase a power supply AC/DC switch (40) simultaneously with alternating current or powered by direct current.
In order to make this instrument also can be used to measure the online exchange current value simultaneously, in the electronic circuit of original gauge internal, increase a bidirectional drive and AC/DC changeover switch, and on watchcase, increase (current value is measured and a selected) switch (13) that links to each other with AC/DC changeover switch.
Mentioned in the present embodiment range switch, the general knob that adopts, other all kinds of switches can adopt push-key type or knob or movable type, the distribution of above-mentioned each parts surface position can be done various adjustment according to fabricator and user's needs, and concrete connection of each parts and internal circuit addressed in Fig. 1 and Fig. 2.
Referring to Fig. 4, the operational instances step that the online circuit measuring instrument that has independent constant current source that utilizes the utility model to provide detects printed circuit board (PCB) or other electric device location of short circuit is as follows:
Contacting two respectively with two test pencils (41,42) of drawing on the constant-current contour jack (23,24) exists the lead (43,44) of short circuit to make it by the Constant Direct Current electric current, test pencil (41,42) is M, N 2 points with the contact position of lead, two test pencils (3,4) that to draw from the on-line testing of this instrument part (45) again contact with 2 of J, K on the lead (43,44) respectively.If the location of short circuit between two leads is in E, F 2 points, there is electric current to pass through between the line segment MEFN like this, at 2 because of J, K drop between the line segment EM, so there is electric current to show on this instrument ammeter (8).When test pencil (3,4) when 2 of H, G on the lead (43,44) contacts, because of no current between line segment H, the G passes through, so going up no current, ammeter (8) shows, can judge that in view of the above the location of short circuit between two leads (43,44) is in left side rather than the right side of 2 of M, N, analogize with the method, promptly can find location of short circuit rapidly accurately is E, F 2 points.
Referring to Fig. 5, this is the operational instances that an online circuit measuring instrument that has independent constant current source and millivolt generator that utilizes utility model to provide is checked the electric fault position in the automation equipment: this device is by reaction tower (46), temperature sensor (47), transducing unit (48), ratio, differential, integrator computing unit (49), topworks (50) constitutes.When detecting, can be with the measurement test pencil (51,52) of millivolt generator (28), insert input end L, R 2 points of transducing unit, simultaneously temperature sensor output is disconnected, again surveying in line current of this instrument examined the test pencil (3,4) that part (45) is drawn, on the circuit behind the output terminal of access transducing unit between TV or the SU.The adjusting turn-knob (39) of potentiometer Rp2 by millivolt generator and ammeter (8) are to required standard voltage value of transducing unit input, and the current value of observing transducing unit output is to judge whether its duty is normal.For of the size decision of its operating state of topworks (50) by input current value, so the test pencil (41,42) of constant current source (21) can be inserted its input end W, Z, whether adjusting knob (36) and the ammeter (8) of the potentiometer Rp3 by constant current source be normal with the duty of examining topworks to required standard current value of topworks.For ratio, differential, the integral operation detection that also uses the same method.
At last, should be noted that the step that provides in the electronic circuit that provides in the various embodiments described above and each parts on the watchcase and the operational instances and method only are explanations but in no case are intended to limit the utility model.Those be should be appreciated that well-trained in the art personnel: he can make various variants and improvement, and does not depart from the spirit of utility model.
Claims (10)
1, a kind of online circuit measuring instrument, the test that belongs to electrical property and fault in the electric measuring instrument is equipped with.This instrument comprises an operational amplifier [5] and a pair of test pencil I [3] and the II [4] that link to each other with its input end, test pencil I [3] links to each other with the output terminal of operational amplifier [5] simultaneously, test pencil II [4] links to each other with the input end of measuring amplifier [7], this test pencil II [4] links to each other with resistance R 2, R2 ground connection, the output terminal of measuring amplifier [7] and ammeter [8] associated, of the present utility model being characterised in that, also have an independently constant-current source circuit [21] in this instrument, a constant current source switch [15] is housed on the watchcase.
2, according to the described instrument of claim 1, it is characterized in that, in above-mentioned constant-current source circuit (21), increase a potentiometer RP3, and a constant current source adjusting turn-knob (36) is housed on watchcase.
3, according to the instrument described in claim 1 or 2, it is characterized in that, above-mentioned measuring amplifier (7) connect afterwards a warning circuit (26) and the sounding that links to each other with this circuit and or luminescent device (27), and a switch (25) of controlling warning circuit is housed on watchcase.
4, according to the instrument described in the claim 3, it is characterized in that, wherein increase an adjustable millivolt generator circuit (28) that indication is arranged, and on watchcase, increase the millivolt generator adjusting knob (29) that a switch (29) that is used for controlling the millivolt generator circuit and are used to regulate the potentiometer of this circuit again.
5, according to the instrument described in claim 1 or 2 or 4, it is characterized in that, be connected in series a bidirectional current driver (18) again between above-mentioned operational amplifier (5) and the electroprobe I (3), between measuring amplifier (7) output terminal and ammeter (8), be connected in series an AC/DC changeover switch (19) simultaneously, and on watchcase, an online alterating and direct current flow valuve measuring light electric switch (13) be installed.
6, according to the instrument described in the claim 3, it is characterized in that, be connected in series a bidirectional current driver (18) again between above-mentioned operational amplifier (5) and the electroprobe I (3), between measuring amplifier (7) output terminal and ammeter (8), be connected in series an AC/DC changeover switch (19) simultaneously, and an online alterating and direct current flow valuve be installed on watchcase measure selector switch (13).
7, according to the instrument described in claim 1 or 2 or 4 or 6, it is characterized in that, wherein set up a DC to DC converter (33) again, adopt powered battery, and on watchcase, set up a power supply AC-DC switch (40).
8, according to the instrument described in the claim 3, it is characterized in that, wherein set up a DC to DC converter (33) again, adopt powered battery, and on watchcase, set up a power supply AC-DC switch (40).
9, according to the instrument described in the claim 5, it is further characterized in that, has wherein set up a DC to DC converter (33) again, adopts powered battery, and set up a power supply AC-DC switch (40) on watchcase.
10, a kind of online circuit measuring instrument, the testing apparatus that belongs to electrical property and fault in the electric measuring instrument, this instrument comprises an operational amplifier (5) and a pair of test pencil I (3) and the II (4) that link to each other with its input end, test pencil I (3) links to each other with the output terminal of operational amplifier (5) simultaneously, test pencil II (4) links to each other with resistance R 2, R2 ground connection, the output terminal of measuring amplifier (7) and ammeter (8) associated, of the present utility model being characterised in that, be connected in series a bidirectional current driver (18) again between operational amplifier in above-mentioned instrument (5) and the electroprobe I (3), between measuring amplifier (7) output terminal and ammeter (8), be connected in series an AC/DC changeover switch (19) simultaneously, and an online alterating and direct current flow valuve be installed on watchcase measure selector switch (13).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85201419 CN85201419U (en) | 1985-04-21 | 1985-04-21 | Multifunctional on-line circuit tester |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85201419 CN85201419U (en) | 1985-04-21 | 1985-04-21 | Multifunctional on-line circuit tester |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN85201419U true CN85201419U (en) | 1986-06-04 |
Family
ID=4797489
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 85201419 Ceased CN85201419U (en) | 1985-04-21 | 1985-04-21 | Multifunctional on-line circuit tester |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN85201419U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102221656A (en) * | 2010-04-19 | 2011-10-19 | 鸿富锦精密工业（深圳）有限公司 | Short circuit tester |
| CN101283282B (en) * | 2005-09-07 | 2012-05-30 | Trw有限公司 | Current measurement circuit and method of diagnosing a fault in a current measurement circuit |
-
1985
- 1985-04-21 CN CN 85201419 patent/CN85201419U/en not_active Ceased
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101283282B (en) * | 2005-09-07 | 2012-05-30 | Trw有限公司 | Current measurement circuit and method of diagnosing a fault in a current measurement circuit |
| CN102221656A (en) * | 2010-04-19 | 2011-10-19 | 鸿富锦精密工业（深圳）有限公司 | Short circuit tester |
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