1. A multifunctional component testing device is characterized by comprising a working panel, a first power supply, an alternating current-direct current conversion mechanism, a second power supply, a transformer in a shape of Chinese character ri or E and a resistance box, wherein the working panel is connected with the first power supply through a connecting wire; the first power supply comprises a plurality of groups of tapped power transformers; the working panel is provided with a first voltmeter, a first ammeter, a second voltmeter and a second ammeter; the first voltmeter, the first ammeter, the second voltmeter and the second ammeter are connected with the second power supply and are powered by the second power supply; an L-shaped iron core wound on the middle part of the transformer in a shape like the Chinese character 'ri' or E₁A coil with a left side iron core wound with L₂A coil with L wound on the right side₃A coil; said L₂Coil and said L₃The number of turns of the coil is equal, L₁The number of turns of the coil is L₂Twice as many coils; said L₁The coil is electrically connected with the output end of the power transformer, and the L₂A coil for electrical connection with the device under test, the L₃The coil is used for being electrically connected with the resistance box; said L₂A first alternating current-direct current conversion mechanism is arranged between the coil and the tested device, and alternating current is converted into direct current through the first alternating current-direct current conversion mechanism and is output to the tested device; the first voltmeter is connected in parallel to the output end of the first alternating current-direct current conversion mechanism, and meanwhile, the first ammeter is arranged at the output end of the first alternating current-direct current conversion mechanism and is connected with the device to be tested in series; said L₃Between the coil and the resistance boxThe second alternating current-direct current conversion mechanism is arranged and used for converting alternating current into direct current and outputting the direct current to the resistance box; the second voltmeter is connected in parallel to the output end of the second alternating current-direct current conversion mechanism, and meanwhile, the second ammeter is arranged at the output end of the second alternating current-direct current conversion mechanism and is connected in series with the resistance box.

2. A multifunctional component testing device as claimed in claim 1, wherein: said L₁The coil is provided with three taps, namely a first tap, a second tap and a third tap, wherein the number of turns from the first tap to the third tap is twice that from the first tap to the second tap; said L₁The coil is electrically connected with the output end of the power transformer through the first tap and the second tap or is electrically connected with the output end of the power transformer through the first tap and the third tap.

3. A multifunctional component testing device as claimed in claim 1, wherein: said L₂Coil and L₃Two taps are arranged on the coil, and the L₂The coil is connected with the input end of the first alternating current-direct current conversion mechanism through the two taps; said L₃And the coil is connected with the input end of the second alternating current-direct current conversion mechanism through the two taps.

4. A multifunctional component testing device as claimed in claim 1, wherein: the first power supply further comprises output binding posts, and the two output binding posts are used for being connected with the output end of the power transformer; and the output binding post is detachably connected with a lead.

5. A multifunctional component testing device as claimed in claim 2, wherein: the working panel is also provided with a left wiring terminal, a middle wiring terminal and a right wiring terminal; the two left binding posts are used for connecting the output end of the first alternating current-direct current conversion mechanism(ii) a The left wiring terminal is detachably connected with a lead, and the tested device is externally connected through the lead; three middle binding posts are used for connecting the L₁Three taps on the coil; the two right binding posts are used for being connected with the output end of the second alternating current-direct current conversion mechanism, and the right binding posts are detachably connected with wires which are externally connected with the resistance box.

6. A multifunctional component testing device as claimed in claim 1, wherein: the first alternating current-direct current conversion mechanism and the second alternating current-direct current conversion mechanism are both rectifier filters, and each rectifier filter comprises a rectifier circuit and a filter circuit.

7. A multifunctional component testing device as claimed in claim 1, wherein: the working panel is provided with a power supply mounting hole, the first power supply is fixed on the working panel and positioned in the power supply mounting hole, and the transformer in the shape of Chinese character 'ri' or 'E' is arranged at the top end of the first power supply and positioned at the rear part of the working panel; the resistance box is fixed at the front part of the working panel; the second power supply is fixed at the rear part of the working panel.

8. A multifunctional component testing device as claimed in claim 4, wherein: the first power supply is a J1202 high school student power supply.

9. A multifunctional component testing device as claimed in claim 1, wherein: the resistance box can be replaced by a slide rheostat.

10. A multifunctional component testing device as claimed in claim 1, wherein: the first voltmeter, the first ammeter, the second voltmeter and the second ammeter use a 5135 digital display panel meter.

Background

At present high school's physical teaching mode is comparatively single, and on physics class, the teacher generally utilizes the lecture method to explain this partial content, and the experiment that also hardly utilizes is very few simulates, and the teacher can write a lot of physical formulas on the blackboard and come to impart knowledge to students and strengthen the training, and more classroom time is taken to numerous formula, and the student lacks actual exercise for classroom teaching is boring and tasteless, influences teaching time and teaching quality.

In addition, the existing experimental equipment for electrical teaching is not rich enough in content, single in function, not strong in binding force and inconvenient to detect.

Therefore, the multifunctional component testing device is researched and improved aiming at the defects in the existing teaching, and not only can show the forward characteristic of the diode and the volt-ampere characteristic of the bulb to students, but also can obtain the resistance value of the resistor and the voltage stabilizing value of the voltage stabilizing diode.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, provides a multifunctional component testing device, and can effectively solve the problems that the existing electrical teaching experimental equipment is not rich in content, single in function, not strong in binding force and not convenient and fast to detect.

The invention is realized by the following technical scheme:

a multifunctional component testing device comprises a working panel, a first power supply, an alternating current-direct current conversion mechanism, a second power supply, a transformer shaped like Chinese character ' ri ' or E ' and a resistance box; the first power supply comprises a plurality of groups of tapped power transformers; the working panel is provided with a first voltmeter, a first ammeter, a second voltmeter and a second ammeter; the first voltmeter, the first ammeter, the second voltmeter and the second ammeter are connected with the second power supply and are powered by the second power supply; an L-shaped iron core wound on the middle part of the transformer in a shape like the Chinese character 'ri' or E₁A coil with a left side iron core wound with L₂A coil with L wound on the right side₃A coil; said L₂Coil and said L₃The number of turns of the coil is equal, L₁The number of turns of the coil is L₂Twice as many coils; said L₁The coil is electrically connected with the output end of the power transformer, and the L₂A coil for electrical connection with the device under test, the L₃The coil is used for being electrically connected with the resistance box; said L₂A first alternating current-direct current conversion mechanism is arranged between the coil and the tested device, and alternating current is converted into direct current through the first alternating current-direct current conversion mechanism and is output to the tested device; the first voltmeter is connected in parallel to the output end of the first alternating current conversion mechanism, and meanwhile, the first ammeter is arranged at the output end of the first alternating current conversion mechanism and is connected with the device under test in series; said L₃A coil is arranged between the coil and the resistance boxThe second alternating current-direct current conversion mechanism converts alternating current into direct current through the second alternating current-direct current conversion mechanism and outputs the direct current to the resistance box; the second voltmeter is connected in parallel to the output end of the second alternating current-direct current conversion mechanism, and meanwhile, the second ammeter is arranged at the output end of the second alternating current-direct current conversion mechanism and is connected in series with the resistance box.

Further, according to the multifunctional component testing device of the present invention, the L₁The coil is provided with three taps, namely a first tap, a second tap and a third tap, wherein the number of turns from the first tap to the third tap is twice that from the first tap to the second tap; said L₁The coil is electrically connected with the output end of the power transformer through the first tap and the second tap or is electrically connected with the output end of the power transformer through the first tap and the third tap.

Further, according to the multifunctional component testing device of the present invention, the L₂Coil and L₃Two taps are arranged on the coil, and the L₂The coil is connected with the input end of the first alternating current-direct current conversion mechanism through the two taps; said L₃And the coil is connected with the input end of the second alternating current-direct current conversion mechanism through the two taps.

Further, according to the multifunctional component testing device, the first power supply further comprises output binding posts, and the two output binding posts are used for being connected with the output end of the power transformer; and the output binding post is detachably connected with a lead.

Further, according to the multifunctional component testing device, the working panel is further provided with a left wiring terminal, a middle wiring terminal and a right wiring terminal; the two left binding posts are used for connecting the output end of the first alternating current-direct current conversion mechanism; the left wiring terminal is detachably connected with a lead, and the tested device is externally connected through the lead; three middle binding posts are used for connecting the L₁Three taps on the coil; two right terminals are used for connecting the output end of the second alternating current-direct current conversion mechanism, and the right terminals are detachableThe ground is connected with a lead, and the resistance box is externally connected through the lead.

Further, according to the multifunctional component testing device of the present invention, the first ac/dc converting mechanism and the second ac/dc converting mechanism are both rectifier filters, and each rectifier filter includes a rectifier circuit and a filter circuit.

Further, according to the multifunctional component testing device, a power supply mounting hole is formed in the working panel, the first power supply is fixed to the working panel and located in the power supply mounting hole, and the transformer in a shape like a Chinese character 'ri' or a Chinese character 'E' is arranged at the top end of the first power supply and located at the rear portion of the working panel; the resistance box is fixed at the front part of the working panel; the second power supply is fixed at the rear part of the working panel.

Further, according to the multifunctional component testing device provided by the invention, the first power supply is a power supply for a student in the high school of J1202.

Further, according to the multifunction component testing apparatus of the present invention, the resistance box is replaced with a slide rheostat.

Further, according to the multifunctional component testing device, the first voltmeter, the first ammeter, the second voltmeter and the second ammeter use a 5135 digital display panel meter.

The invention can effectively solve the problems of insufficient contents, single function, weak binding force and inconvenient detection of the existing electrical teaching experimental equipment, and has the advantages of simple manufacture, low cost, convenient operation and accurate test.

Drawings

FIG. 1 is a schematic diagram of magnetic flux when two output terminals of a transformer shaped like Chinese character ri or E are connected with the same load.

Fig. 2 is a schematic diagram of magnetic flux when one output end of a transformer in a shape of Chinese character ri or E is connected with a load and the other is unloaded.

FIG. 3 is a schematic diagram of magnetic flux when two output terminals of a transformer shaped like Chinese character ri or E are connected with different loads.

Fig. 4 is a structural view of the first embodiment of the present invention.

Fig. 5 is a circuit diagram of a first embodiment of the present invention.

Fig. 6 is a circuit diagram of the second power supply, the first voltmeter, the first ammeter, the second voltmeter, and the second ammeter according to the first embodiment of the present invention.

In the figure:

1 working panel, 11 first voltmeter, 12 first ammeter, 13 second voltmeter, 14 second ammeter, 15 left terminal, 16 middle terminal, 17 right terminal, 2 first power supply, 21 power transformer, 22 output terminal, 3 first AC/DC conversion mechanism, 4 second AC/DC conversion mechanism, 5 second power supply, 6-Ri-shaped or E-shaped transformer, 61L₁Coil, 62L₂Coil, 63L₃Coil, 7 resistance box.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Firstly, the experimental phenomenon of the transformer 6 shaped like a Chinese character ri or E is detected: an L1 coil 61 is wound on the iron core in the middle of the transformer 6 in a shape of Chinese character ri or E, an L2 coil 62 is wound on the iron core on the left side, and an L3 coil 63 is wound on the iron core on the right side; the L2 coil 62 has the same number of turns as the L3 coil 63, and the L1 coil 61 has twice the number of turns as the L2 coil 62. In the experiment of the transformer 6 of the japanese-character type or the E-character type, when ac power was input from the coil 61 of the L1 (the intermediate winding), the magnetic flux that changes was equally divided between the iron cores on both sides, and the same induced voltage (of course, the induced voltage is different depending on the number of turns) was generated in the coil 62 of the L2 and the coil 63 of the L3, and the transformation ratio was half of the original transformation ratio. When the L2 coil 62 and the L3 coil 63 are respectively connected with loads, the induction voltage with large resistance is high, the induction voltage with small resistance is low, but the currents on the two sides can be kept consistent, and the circuit is similar to a series circuit; on the transformer 6 shaped like Chinese character 'ri' or EThe change of the magnetic flux is shown in fig. 1, fig. 2 and fig. 3, and the experimental data is shown in the following table one (input alternating current 16V).

Group by group

1

2

3

4

5

6

7

8

9

10

Load 1

Air conditioner

0.5Ω

25Ω

5Ω

10Ω

15Ω

25Ω

15Ω

10Ω

10Ω

V1

4.80V

0.00V

0.00V

0.76V

1.66V

2.51V

3,72V

2.25V

1.50V

1.92V

A1

0mA

0mA

0mA

149mA

167mA

167mA

149mA

150mA

150mA

191mA

Load 2

Air conditioner

Air conditioner

Air conditioner

25Ω

15Ω

10Ω

5Ω

15Ω

20Ω

10Ω

V2

4.80V

9.40V

9.40V

3.72V

2.51V

1.66V

0.76V

2.25V

2.99V

1.92V

A2

0mA

0mA

0mA

149mA

167mA

167mA

149mA

150mA

150mA

191mA

Watch 1

As can be seen from the two sets of data 1 and 8 in Table I, L is₂Coils 62 and L₃When the coil 63 (i.e., the two output terminals) is connected to the same load or no load, the magnetic flux input into the coil 61 of L1 is equally distributed between the two output terminals, as shown in fig. 1; so that the voltages at the two outputs are equal.

As can be seen from the two sets of data 2 and 3 in Table I, at one output (in L)₂Coil 62 for example) is connected to the load, a small current can be generated in the secondary coil of the connected loadGenerating magnetic flux opposite to the original magnetic flux by counter electromotive force, and repelling the majority of the original magnetic flux to one side of no load, as shown in fig. 2; therefore, the output voltage of the no-load side is twice that of the two output ends when the two output ends are in no-load; the voltage at the output terminal connected to the load is 0V.

As can be seen from the four sets of data 4, 5, 6 and 7 in Table I, L is₂Coils 62 and L₃When the coil 63 (i.e., two output ends) is connected to different loads, the reverse magnetic fluxes generated by the two output currents are different (although the currents are the same), the blocking effect on the original magnetic flux is small when the load is small, and the blocking effect on the original magnetic flux is large when the load is large, as shown in fig. 3 specifically; therefore, the output terminal voltage is low when the load is large (the resistance is small), and the output terminal voltage is high when the load is small (the resistance is large).

From the 10 th set of data in table one, it can be seen that the total load increases on both sides, and the current on both loads increases simultaneously.

In addition, according to the working principle of the transformer, when the output current affects the primary magnetic flux, the current is increased in the primary coil to counteract the effect of the output current on the primary magnetic flux, so that the magnetic flux in the magnetic circuit reaches the original balance (the primary magnetic flux does not change, but is distributed to the left and the right by a certain amount).

Example one

As shown in fig. 4 and 5, the multifunctional component testing device includes a working panel 1, a first power supply 2, a first ac/dc conversion mechanism 3, a second ac/dc conversion mechanism 4, a second power supply 5, a transformer 6 shaped like a Chinese character ri or E, and a resistance box 7; a power supply mounting hole is formed in the working panel 1, the first power supply 2 is fixed on the working panel 1 and is positioned in the power supply mounting hole, and the transformer 6 in a shape like a Chinese character 'ri' or 'E' is arranged at the top of the first power supply 2 and is positioned at the rear part of the working panel 1; the resistance box 7 is fixed at the front part of the working panel 1, so that the use is convenient; the working panel 1 is provided with a first voltmeter 11, a first ammeter 12, a second voltmeter 13, a second ammeter 14, two left terminals 15, three middle terminals 16 and two right terminals 17. The first voltmeter 11, the first ammeter 12, the second voltmeter 13 and the second ammeter 14 are respectively connected with the second power supply 5, and are connected with the first power supply 5 throughThe second power supply 5 supplies power, and a power supply circuit is shown in fig. 6; the second power supply 5 can be fixed at the rear part of the working panel 1, namely, the second power supply is uniformly fixed on the working panel 1, so that the device is convenient to take and place, and meanwhile, the device can be prevented from being easily damaged due to no fixation when being hung in use. The first power supply 2 comprises a power transformer 21 with a plurality of groups of taps and two output terminals 22, and the two output terminals 22 are connected to the output end of the power transformer 21; the output terminal 22 is detachably connected with a lead. An L-shaped or E-shaped iron core in the middle of the transformer 6 is wound₁A coil 61 with a left core wound with L₂A coil 62 with an L wound on the right side core₃A coil 63; l is₂Coil 62 and L₃Equal turns of coil 63, L₁The number of turns of the coil 61 is L₂Twice as many coils 62. In particular, L₁The coil 61 is provided with three taps, namely a first tap, a second tap and a third tap, wherein the number of turns from the first tap to the third tap is twice that from the first tap to the second tap; in this example, L₁The number of turns of the coil 61 is 600 turns, L₂Coil 62 and L₃The number of turns of the coil 63 is 300 turns. That is, L₁The number of turns of the first to third taps in the coil 61 is 600 turns, and the number of turns of the first to second taps is 300 turns. The first tap is connected with the leftmost middle binding post 16 on the working panel 1, the second tap is connected with the middle binding post 16 on the working panel 1, and the third tap is connected with the rightmost middle binding post 16 on the working panel 1. The first power supply 2 connects one output terminal 22 with the intermediate terminal 16 connected with the first tap through a wire; connecting the other output terminal 22 to the intermediate terminal 16 connected to the second tap or the third tap by a wire; namely, the connection between the first power supply 2 and the transformer 6 shaped like a Chinese character ri or E is completed, and the AC output is transmitted to the transformer 6 shaped like a Chinese character ri or E through the first power supply 2. L is₂Two taps, L, are provided on the coil 62₂The coil 62 is connected with the input end of the first alternating current-direct current conversion mechanism 3 through two taps; the output end of the first alternating current-direct current conversion mechanism 3 is connected with two left binding posts 15; a lead wire is detachably connected to the left binding post 15 and connected with the left binding post through the lead wireExternal device under test (load) connections; meanwhile, the first voltmeter 11 is connected in parallel to the output end of the first ac/dc conversion mechanism 3, the first ammeter 12 is arranged at the output end of the first ac/dc conversion mechanism 3 and is connected in series with the device (load) to be tested, and the first ac/dc conversion mechanism 3 is used for converting the ac power into the dc power and outputting the dc power to the device (load) to be tested. L is₃Two taps, L, are provided on the coil 63₃The coil 63 is connected with the input end of the second alternating current-direct current conversion mechanism 4 through two taps; the output end of the second alternating current-direct current conversion mechanism 4 is connected with two right binding posts 17; the right binding post 17 is detachably connected with a lead and is connected with the resistance box 7 (load) through the lead; meanwhile, a second voltmeter 13 is connected in parallel to the output end of the second ac/dc conversion mechanism 4, a second ammeter 14 is arranged at the output end of the second ac/dc conversion mechanism 4 and is connected in series with the resistance box 7 (load), and the second ac/dc conversion mechanism 4 is used for converting the ac power into the dc power and outputting the dc power to the resistance box 7 (load). Those skilled in the art will appreciate that the positions of the device under test and the resistor box 7 may be interchanged; the device can be used for detecting the resistance value of the fixed-value resistor and testing the volt-ampere characteristic of the laboratory small bulb.

Further, the first ac/dc conversion mechanism 3 and the second ac/dc conversion mechanism 4 are both rectifier filters, and each rectifier filter includes a rectifier circuit and a filter circuit. Specifically, the rectification circuit may be bridge rectification; the filter circuit can be a filter capacitor, and the filter capacitor is connected in parallel with the output end of the bridge rectifier.

Further, the first power supply 2 is a J1202 high school student power supply.

Further, the first voltmeter 11, the first ammeter 12, the second voltmeter 13, and the second ammeter 14 use a 5135 high-precision digital display panel meter.

The testing method of the device comprises the following steps:

1. resistance measured value: connecting an external power supply; the first voltmeter 11, the first ammeter 12, the second voltmeter 13 and the second ammeter 14 are supplied with power through the second power supply 5; the alternating current output voltage of the first power supply 2 is regulated to be the lowest through the power transformer 21; a binding post 22 is connected with the working panel 1 through a leadConnection L₁The middle terminal 16 of the first tap of the coil 61 is connected, and the other terminal 22 is connected with the working panel 1 through a lead wire L₁The middle terminal 16 of the second tap of the coil 61 is electrically connected (i.e. two ends of 300 turns); the left binding post 15 is electrically connected with the fixed value resistor through a lead, and the right binding post 17 is electrically connected with the resistor box 7 through a lead; (attention is paid to a small power resistor, the current is controlled to be about 10 mA; and attention is paid to a large power resistor, the current is controlled to be about 100 mA). At this time, the resistance value of the resistor box 7 is adjusted so that the first voltmeter 11 and the second voltmeter 13 have the same value, and the read resistance value of the resistor box 7 is the resistance value of the fixed-value resistor. The resistance box 7 is a standard resistance box, and the higher the precision of the resistance box 7 is, the higher the precision of the device is. Compared with a Wheatstone bridge resistor, the device is simple to use and high in precision. Because the sensitive current meter for the wheatstone bridge presents mechanical resistance, the device is flux transfer and there is no resistance.

2. Test voltammetric characteristics of laboratory small bulbs: connecting an external power supply; the first voltmeter 11, the first ammeter 12, the second voltmeter 13 and the second ammeter 14 are supplied with power through the second power supply 5; the AC output voltage of the first power supply 2 is adjusted to 10V, and a wiring terminal 22 is connected with the working panel 1 through a lead L₁The middle terminal 16 of the first tap of the coil 61 is connected, and the other terminal 22 is connected with the working panel 1 through a lead wire L₁The middle terminal 16 of the second tap of the coil 61 is connected (i.e. two ends of 300 turns); then, the left wiring terminal 15 is electrically connected with a small bulb in a laboratory through a wire, the right wiring terminal 17 is electrically connected with the resistance box 7 through a wire, and the resistance box 7 is a standard resistance box and is adjusted to be the maximum; next, the resistance value of the resistance box 7 is adjusted (starting from × 1000); when the first ammeter 12 reading reaches 0.3000A, the regulation is stopped. And finally, drawing the characteristics of the small laboratory bulb in a plane coordinate system by using the obtained multiple groups of data. The data sets obtained by the experiment are multiple, and the drawn characteristic diagram is more standard.

Example two

Unlike the first embodiment, the resistance box 7 is replaced with a slide rheostat; the device can be used for testing the forward characteristic of the diode and the voltage-stabilizing value of the voltage-stabilizing diode. The resistance box 7 and the sliding rheostat (50 Ω) are available from the laboratory. (ii) a The person skilled in the art understands that the alternatives to the resistor box 7 are not limited to slide varistors.

The testing method of the device comprises the following steps:

1. testing the forward characteristics of the diode: connecting an external power supply; the first voltmeter 11, the first ammeter 12, the second voltmeter 13 and the second ammeter 14 are supplied with power through the second power supply 5; the alternating current output voltage of the first power supply 2 is regulated to be the lowest through the power transformer 21; a terminal 22 is connected to the working panel 1 by a conductor line L₁The middle terminal 16 of the first tap of the coil 61 is connected, and the other terminal 22 is connected with the working panel 1 through a lead wire L₁The middle terminal 16 of the third tap of the coil 61 is connected (i.e. two ends of 600 turns); then the left binding post 15 is electrically connected with the diode through a lead, and the right binding post 17 is electrically connected with the slide rheostat through a lead; the slide rheostat is adjusted to the maximum value; the first voltmeter 11 and the first ammeter 12 are respectively connected to the diode at this time, and the number of the first voltmeter 11 and the number of the first ammeter 12 are respectively 0.0000A. Adjusting the alternating current output voltage (from low to high) of the first power supply 2, wherein the number of the first voltmeter 11 is 0.451V, and the number of the first ammeter 12 is 0.0008A; the first voltmeter 11 is 0.576V, and the first ammeter 12 is 0.0109A; the first voltmeter 11 is 0.647V, the first ammeter 12 is 0.0259A; the first voltmeter 11 indicates 0.697V, and the first ammeter 12 indicates 0.0418A. On the basis, the resistance value of the slide rheostat is gradually reduced, a plurality of groups of numerical values are read out as required, and finally the forward characteristic curve of the diode can be drawn in a plane coordinate system.

2. Testing the voltage stabilizing value of the voltage stabilizing diode: connecting an external power supply; the first voltmeter 11, the first ammeter 12, the second voltmeter 13 and the second ammeter 14 are supplied with power through the second power supply 5; the alternating current output voltage of the first power supply 2 is regulated to be the lowest through the power transformer 21; a terminal 22 is connected to the working panel 1 by a conductor line L₁The middle terminal 16 of the first tap of the coil 61 is connected, and the other terminal 22 is connected with the working panel 1 through a lead wire L₁Coil61 the middle post 16 of the second tap is connected (i.e. two ends of 300 turns); then the left binding post 15 is electrically connected with the voltage stabilizing diode through a lead, and the right binding post 17 is electrically connected with the slide rheostat through a lead; then adjusting the slide rheostat to the maximum value; at this time, the first voltmeter 11 indicates 1.057V, and the first ammeter 12 indicates 0.0000A. Subsequently, the alternating current output voltage of the first power supply 2 is adjusted; when the first ammeter 12 has a reading, the high voltage is stopped to be regulated, and the reading of the first voltmeter 11 is the regulated voltage value of the voltage regulator diode.