CN203241479U - Inductance and capacitance measuring instrument based on switching circuit - Google Patents
Inductance and capacitance measuring instrument based on switching circuit Download PDFInfo
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- CN203241479U CN203241479U CN 201320306160 CN201320306160U CN203241479U CN 203241479 U CN203241479 U CN 203241479U CN 201320306160 CN201320306160 CN 201320306160 CN 201320306160 U CN201320306160 U CN 201320306160U CN 203241479 U CN203241479 U CN 203241479U
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Abstract
An inductance and capacitance measuring instrument based on a switching circuit relates to an inductance and capacitance measuring instrument. The utility model aims to solve the problem that a bridge is not suitable for measuring inductance and capacitance in a switching circuit and is high in cost currently. The inductance and capacitance measuring instrument comprises an inductance measuring circuit, a capacitance measuring circuit, a single chip microcomputer control system, a display, a keyboard circuit and a power circuit. An inductance measuring signal input-output end of the inductance measuring circuit is connected with an inductance measuring signal input-output end of the single chip microcomputer control system; a capacitance measuring signal input-output end of the capacitance measuring circuit is connected with a capacitance measuring signal input-output end of the single chip microcomputer control system; a display signal output end of the single chip microcomputer control system is connected with a display signal input end of the display; a keyboard signal output end of the keyboard circuit is connected with a keyboard signal input end of the single chip microcomputer control system; and the power circuit provides working power for the inductance measuring circuit, the capacitance measuring circuit, the single chip microcomputer control system, the display and the keyboard circuit. The inductance and capacitance measuring instrument is used for measuring inductance and capacitance.
Description
Technical field
The utility model relates to a kind of inductance and capacitance measureing instruments, particularly a kind of inductance and capacitance measureing instruments based on on-off circuit.
Background technology
Switching Power Supply is generally used now, but does not also have a kind of capacitor and inductance measurement instrument of suitable Switching Power Supply.It mainly is electric bridge that present inductance capacitance is measured, and adopts sinusoidal excitation, measures reactance and comes indirect inductance measuring electric capacity.And the inductance capacitance in the on-off circuit works in the non-sinusoidal state.So the employing electric bridge is not suitable for the inductance capacitance in the measuring switch circuit, and the electric bridge cost is high.
The utility model content
The purpose of this utility model is to be not suitable for inductance capacitance in the measuring switch circuit in order to solve present employing electric bridge, and the high problem of electric bridge cost, and a kind of inductance and capacitance measureing instruments based on on-off circuit are provided.
Inductance and capacitance measureing instruments based on on-off circuit of the present utility model, it comprises inductance measurement circuit, capacitance measurement circuit, single-chip computer control system, display, keyboard circuit and power circuit;
The inductance measurement signal input output end of inductance measurement circuit is connected with the inductance measurement signal input output end of single-chip computer control system, the capacitance measurement signal input output end of capacitance measurement circuit is connected with the capacitance measurement signal input output end of single-chip computer control system, the display output terminal of single-chip computer control system is connected with the display input end of display, and the keyboard signal output terminal of keyboard circuit is connected with the keyboard signal input end of single-chip computer control system;
Power circuit provides working power for inductance measurement circuit, capacitance measurement circuit, single-chip computer control system, display and keyboard circuit.
The utility model has the advantage of: inductance measuring value range of the present utility model arrives 10mH at 10uH, measure the electric capacity range and arrive 10uF at 10pF, error precision is better than 2%, error has reduced by 50%, use simultaneously on-off circuit inductance measuring and electric capacity, simple in structure, easy to carry, and the cost of the element that adopts is lower.
Description of drawings
Fig. 1 is the principle schematic of the inductance and capacitance measureing instruments based on on-off circuit described in the utility model.
Fig. 2 is the principle schematic of inductance measurement circuit of the present utility model.
Fig. 3 is the principle schematic of capacitance measurement circuit of the present utility model.
Fig. 4 is the basic principle schematic of capacitance measurement circuit of the present utility model.
Fig. 5 is the principle schematic of the utility model embodiment seven described power circuits.13 are the charging jack.
Fig. 6 is the matched curve schematic diagram of the data of the utility model inductance of measuring respectively solid coil and air core coil.
Fig. 7 is the linear diagram of the reading of the inductance measured of the utility model.
Embodiment
Embodiment one: present embodiment is described in conjunction with Fig. 1 and Fig. 2, inductance and capacitance measureing instruments based on on-off circuit of the present utility model, it comprises inductance measurement circuit 1, capacitance measurement circuit 2, single-chip computer control system 3, display 4, keyboard circuit 5 and power circuit 6;
The inductance measurement signal input output end of inductance measurement circuit 1 is connected with the inductance measurement signal input output end of single-chip computer control system 3, the capacitance measurement signal input output end of capacitance measurement circuit 2 is connected with the capacitance measurement signal input output end of single-chip computer control system 3, the display output terminal of single-chip computer control system 3 is connected with the display input end of display 4, and the Keyboard Control signal output part of keyboard circuit 5 is connected with the Keyboard Control signal input part of single-chip computer control system 3;
Inductance measurement circuit to the two-way charging of tested inductance, is measured the next indirect inductance measuring value of tD discharge time by constant-current source circuit Is.
Embodiment two: in conjunction with Fig. 2 present embodiment is described, present embodiment is the further restriction to the described inductance and capacitance measureing instruments based on on-off circuit of embodiment one,
Described inductance measurement circuit 1 comprises current source 8, the first diode D1, the second diode D2, the first electronic switching circuit 9, the second electronic switching circuit 10, the 3rd electronic switching circuit 11 and quadrielectron on-off circuit 12;
The current output terminal of current source 8 is connected with an end of the first electronic switching circuit 9 and an end of the 3rd electronic switching circuit 11 simultaneously, the other end of the first electronic switching circuit 9 simultaneously with the negative electrode of the first diode D1 be connected an end of electronic switching circuit 10 and be connected afterwards as a tested inductance incoming end, the other end of the 3rd electronic switching circuit 11 is connected rear as another tested inductance incoming end, the other end of the second electronic switching circuit 10 with the negative electrode of the second diode D2 and an end of quadrielectron on-off circuit 12 simultaneously, the other end of quadrielectron on-off circuit 12, the anode of the anode of the first diode D1 and the second diode D2 connects the power supply ground of power supply VCC simultaneously; The negative electrode of the first diode D1 is connected with the first signal input end of single-chip computer control system 3, the first control signal output terminal of single-chip computer control system 3 is connected with the switch control end of the first electronic switching circuit 9, the second control signal output terminal of single-chip computer control system 3 is connected with the switch control end of the second electronic switching circuit 10, the 3rd control signal output terminal of single-chip computer control system 3 is connected with the switch control end of the 3rd electronic switching circuit 11, and the 4th control signal output terminal of single-chip computer control system 3 is connected with the switch control end of quadrielectron on-off circuit 12.
Adopt on-off circuit, current source 8 charges to tested inductance L x, through a diode discharge, with single-chip computer control system Timing measurement stable discharging time t
DCome the former reason formula 1 of inductance measuring value to provide:
T wherein
DThe time period that diode is stablized forward conduction, U
DPThe forward conduction voltage of diode, I
1Is is relevant with constant current source, I
2Be approximately zero, and the stable discharging electric current is linear decline, Lx is required inductance.
Wherein the first electronic switching circuit 9, the second electronic switching circuit 10, the 3rd electronic switching circuit 11 and quadrielectron on-off circuit 12 formations are to the switch of the Bidirectional charging-discharging of inductance L x, switching logic is as shown in table 1, wherein E1 is the output enable of output signal u1, namely when discharge, just allow to output to single-chip microcomputer, so that the forward conduction time t of measuring diode D2
D, this time t
DLength be directly proportional with the size of inductance value.Back discharge on the D4 is not measured and is used.Be divided into 4 duties, each state has the time interval of 5ms, and design can be measured the inductance of 10mH.Every 20ms takes out a number, thereby per second can be sampled 50 times.
The two-way charge switch logic of table 1
| S4 | S3 | S2 | S1 | E1 | |
| 1 | 0 | 0 | 1 | 0 | |
| 1 | 0 | 0 | 0 | 1 | The |
| 0 | 1 | 1 | 0 | 0 | |
| 0 | 0 | 1 | 0 | 0 | Anti-phase discharge |
Embodiment three: in conjunction with Fig. 2 present embodiment is described, present embodiment is the further restriction to the described inductance and capacitance measureing instruments based on on-off circuit of embodiment two,
Described current source 8 comprises resistance R 1, resistance R 2, resistance R 3, resistance R 4, adjustable resistance VR1 and P channel MOS tube Q1;
One end of resistance R 1 and an end of resistance R 4 link together as the power supply end of current source 1, the end of the other end while contact resistance R2 of resistance R 1 and the adjustable end of adjustable resistance VR1, the other end of resistance R 4 is connected with the source electrode of P channel MOS tube Q1, the stiff end of adjustable resistance VR1 is the other end, the grid of P channel MOS tube Q1 and the end of resistance R 3 of contact resistance R2 simultaneously, the power supply ground of another termination power supply of resistance R 3, the drain electrode of P channel MOS tube Q1 is the current output terminal of current source 1.
Embodiment four: in conjunction with Fig. 2 present embodiment is described, present embodiment is the further restriction to the described inductance and capacitance measureing instruments based on on-off circuit of embodiment two,
Described the first electronic switching circuit 9, the second electronic switching circuit 10, the 3rd electronic switching circuit 11 and quadrielectron on-off circuit 12 form identical, and described the first electronic switching circuit 9 comprises resistance R 111, resistance R 121 and the first N-channel MOS pipe Q11 and a NPN type triode Q111;
The drain electrode of the first N-channel MOS pipe Q11 is connected with the current output terminal of current source 8 as an end of the first electronic switching circuit 9, the grid of the first N-channel MOS pipe Q11 is connected with an end of resistance R 111 and the collector of a NPN type triode Q111 simultaneously, the positive pole of another termination power supply of resistance R 111, the base stage of the one NPN type triode Q111 is connected with an end of resistance R 121, and the emitter of a NPN type triode Q111 connects the power supply ground of power supply; The source electrode of the first N-channel MOS pipe Q11 connects the negative electrode of the first diode D1 as the other end of the first electronic switching circuit 9, the other end of resistance R 121 is switch control ends of the first electronic switching circuit 9.
Embodiment five: in conjunction with Fig. 2 present embodiment is described, present embodiment is the further restriction to the described inductance and capacitance measureing instruments based on on-off circuit of embodiment two,
Single-chip computer control system 3 comprises ARM single-chip microcomputer, resistance R 5-R9, adjustable resistance VR2, the first one-level operational amplifier IC11, the first two-level operating amplifier IC12, the first Sheffer stroke gate (IC13)) and the 3rd diode (D3;
The end that the negative electrode of the first diode D1 is connected with resistance R connects, the other end of resistance R 5 is connected with the forward signal input end of the first one-level operational amplifier IC11, the reverse signal input end of the first one-level operational amplifier IC11 is connected with the end that an end of resistance R 6 is connected with resistance R simultaneously, the power supply ground of another termination power supply of resistance R 7, the other end of resistance R 6 simultaneously with the signal output part of the first one-level operational amplifier IC11 be connected the reverse signal input end of two-level operating amplifier IC12 and be connected, the forward signal input end of the first two-level operating amplifier IC12 is connected with the sliding end of adjustable resistance VR2, one of the adjustable resistance VR2 fixing power supply ground of termination power supply, another of adjustable resistance VR2 fixedly the termination power supply negative pole, the signal output part of the first two-level operating amplifier IC12 is connected with an end of resistance R 8, the other end while of resistance R 8 and the negative electrode of the 3rd diode (D3), one end of resistance R 9 be connected input end of Sheffer stroke gate (IC13) and connect, the anode of the other end of resistance R 9 and the 3rd diode (D3) connects the power supply ground of power supply simultaneously, another input end of the first Sheffer stroke gate (IC13) is connected with the first signal output terminal of ARM single-chip microcomputer, and the output terminal of the first Sheffer stroke gate (IC13) is connected with the signal input part of ARM single-chip microcomputer;
The 3rd signal output part of ARM single-chip microcomputer is the first control signal output terminal of single-chip computer control system 3 and is connected with the switch control end of the first electronic switching circuit 9; The 4th signal output part of ARM single-chip microcomputer is the second control signal output terminal of ARM single-chip microcomputer 3 and is connected with the switch control end of the second electronic switching circuit 10, the 5th signal output part of ARM single-chip microcomputer is that the 3rd control signal output terminal of ARM single-chip microcomputer 3 is connected with the switch control end of the 3rd electronic switching circuit 11, the 6th signal output part of ARM single-chip microcomputer is that the 4th control signal output terminal of ARM single-chip microcomputer 3 is connected with the switch control end of quadrielectron on-off circuit 12, the display output terminal of ARM single-chip microcomputer is connected with the display input end of display 4, the keyboard signal output terminal of keyboard circuit 5 is connected with the keyboard signal input end of ARM single-chip microcomputer,, the capacitance measurement signal input output end of capacitance measurement circuit 2 is connected with the capacitance measurement signal input output end of ARM single-chip microcomputer.
Embodiment six: in conjunction with Fig. 3 present embodiment is described, present embodiment is the further restriction to the described inductance and capacitance measureing instruments based on on-off circuit of embodiment one,
Described capacitance measurement circuit 2 comprises resistance R 15-R29, the first positive-negative-positive triode Q1, the second positive-negative-positive triode Q7, NPN type triode Q2-Q6, chip NE555 and capacitor C 2;
One end of the emitter of the first positive-negative-positive triode Q1, an end of resistance R 15 and resistance R 16 connects the positive pole of power supply VCC simultaneously, the base stage of the first positive-negative-positive triode Q1 is connected with the end that the other end of resistance R 15 is connected with resistance R simultaneously, the collector of the first positive-negative-positive triode Q1 is connected with an end of resistance R 19
The collector of one end of the other end of resistance R 19, resistance R 27 and the 2nd NPN type triode Q3 connects rear link as a measured capacitance, the other end of resistance R 27 is connected with the pin 2 of chip NE555, the base stage of the base stage of the 2nd NPN type triode Q3, the 3rd NPN type triode Q4 connects with the end that the collector of the 3rd NPN type triode Q4 is connected with resistance R, the positive pole of another termination power supply VCC of resistance R 20
The emitter of the 2nd NPN type triode Q3 is connected with an end of resistance R 21, the other end of resistance R 21 is connected with the emitter of the 3rd NPN type triode Q4 and the collector of the 4th NPN type triode Q5, the emitter of the 4th NPN type triode Q5 connects the power supply ground of power supply VCC, the power supply ground of this power supply VCC is as the link of another measured capacitance, the 4th NPN type triode Q5 base stage be connected with the other end of resistance R 18;
The pin 5 of chip NE555 is connected with an end of capacitor C 2, the pin 1 of the other end of capacitor C 2 and chip NE555 is the power supply ground of power supply VCC simultaneously, the pin 6 of chip NE555 is connected with an end of resistance R 22 and the collector of the 5th NPN type triode Q6 simultaneously, the emitter of the 5th NPN type triode Q6 connects the power supply ground of power supply VCC, the positive pole of another termination power supply VCC of resistance R 22, the base stage of the 5th NPN type triode Q6 is connected with an end of resistance R 28, and the other end of resistance R 28 is connected with the capacitance measurement signal output part of single-chip computer control system 3;
The other end of resistance R 17, the end that the other end of resistance R 16 is connected with resistance R is connected with the collector of a NPN type triode Q2 simultaneously, the emitter of the one NPN type triode Q2 connects the power supply ground of power supply VCC, the base stage of the one NPN type triode Q2 is connected with an end of resistance R 26, the other end of resistance R 26 simultaneously and an end of resistance R 23 be connected pin 3 with chip NE555 and be connected, the other end of resistance R 23 is connected with the end that the base stage of the second positive-negative-positive triode Q7 is connected with resistance R simultaneously, the emitter of the other end of resistance R 24 and the second positive-negative-positive triode Q7 connects the positive pole of power supply VCC simultaneously, the collector of the second positive-negative-positive triode Q7 is connected with an end of resistance R 29, and the other end of resistance R 29 is connected with the capacitance measurement signal input part that an end of resistance R 25 is connected with single-chip computer control system; The power supply ground of another termination power supply VCC of resistance R 25.
The measuring principle of capacitance measurement circuit for ton, is toff during putting 2 during switch s puts 1 in Fig. 4 as shown in Figure 4, and the cycle is T=ton+toff.E charges to U1 through R to C during ton, if the ton long enough also can charge to E.Charge Q during toff in the capacitor C is discharged over the ground with electric current I o, and the voltage uc on the electric capacity drops to the electric charge that Ur discharges from U1:
delta_Q＝C(U1-Ur)＝Io*toff (2)
So
Measure toff as U1, Ur, when Io is known and just can obtain capacitance C.And toff can obtain by the low level time of comparer IC1 survey uo.
Wherein Io is a little current source loads circuit, is made of Q3 and Q4, R20 and R21 in Fig. 3, and uc is enough high, such as uc＞Ur, makes Io be in sufficiently constant current state, and namely discharge current can not reach because the power supply that enters is not enough the Constant Electric Current flow valuve.During ton, the power supply that Io does not enter and electric current are zero, and corresponding voltage also is zero, make uo output high level.And this Io electric current is measured little electric capacity less than 30uA, and Io is large, then can measure large capacitance.
In Fig. 3, single-chip computer control system is to low level burst pulse of 6 human hair combing wastes of chip 555, make 555 3 pin step-downs, the Q1 cut-off, measured capacitance Cx discharges through constant-current source circuit, until during 4V, 555 2 pin detect, stop the discharge till, the high level time of single-chip microcomputer Timing measurement PD7 as discharge time tD indirectly measure capacitance.
Embodiment seven: in conjunction with Fig. 5 present embodiment is described, present embodiment is the further restriction to the described inductance and capacitance measureing instruments based on on-off circuit of embodiment one,
Described power circuit 6 is the power circuit with charge function, and described power circuit is exported respectively power supply-12V, power supply+12V, power supply-5V, power supply+5V and power supply ground GND.
Consist of the 7--9Vdc DC source with 7 joint rechargeable battery set in the present embodiment, leaving the charging jack can external charger.The voltage of 7--9Vdc DC source is given other circuit through the chopper circuit output positive and negative 12V of direct current and positive and negative 5V.This instrument can be become portable.
The utility model provides an embodiment:
Single-chip computer control system adopts chip LM3S9B96 to realize, specified dominant frequency is 80MHz, but in order to improve timing ga(u)ge numerical value, actual definition is only considered timing function and simple I/O function to 100MHz, can normally move.
Under the condition of original luminary Driver Library, in the initial row of principal function main definition dominant frequency:
SysCtlClockSet (SYSCTL_SYSDIV_2|SYSCTL_USE_PLL|SYSCTL_OSC_MAIN SYSCTL_XTAL_6MHZ); / * enables PLL, and actual crystal oscillator is 6MHz on 100MHz dominant frequency */plate, and to 200MHz, then 2 frequency divisions are 100MHz through frequency multiplication of phase locked loop.
Such timer counter pulse is 10ns, and perhaps each us has 100 count values, for identical tested inductance value, t
DCorresponding count value N
TDDouble.Improved Measurement Resolution, this is favourable to measuring the small inductor value.
With air core coil and I-shaped inductive as tested inductor, the frequency that 100KHz is set with electric bridge HIOKI3532-50LCR is measured basic parameter, frequency is used 100KHz instead without 1KHz be because the inductance value of bridge measurement air core coil is just reasonable at 100KHz, otherwise Ls and Lp differ greatly.
Tested inductance is measured with the metering circuit of Fig. 2 one by one, read respectively timing ga(u)ge numerical value N during the stable discharging from the display screen of single-chip microcomputer
TDOnly get the value of forward discharge, reverse do not have usefulness, oppositely discharges and recharges to be equivalent to as degaussing circuit, as shown in table 2.These data are drawn matched curve as shown in Figure 6 with MATLAB.Transverse axis is inductance reading N
TD, the longitudinal axis is inductance value.Find out from data, the air core inductor of low side and high-end I-shaped inductive are near straight line, and 0-400uH is the air core coil inductance, and 400uH-1mH is I-shaped inductive, comes match with two straight lines.
Table 2 inductance standards value Lr and reading NtD
| Lr(uH) | NtD | Lr(uH) | NtD |
| 987.0 | 34220 | 115.9 | 4380 |
| 701.5 | 26424 | 99.9 | 3936 |
| 510.7 | 19838 | 59.4 | 2264 |
| 396.8 | 15610 | 20.3 | 736 |
| 304.7 | 12222 | 13.4 | 470 |
| 206.0 | 8322 | 8.4 | 276 |
Fitting formula is respectively:
Utilize existing programming to deliver in the single-chip microcomputer fitting formula 4 and 5, and L is shown, realize the inductance value measurement.The inductance value L that reads and standard value Lr and error thereof are as shown in table 3.To the magnetic core inductance, be 0--1mH by full scale, relative accuracy is better than 3%, satisfies Power Management Design to the measuring accuracy of inductance.Air core inductor is pressed full scale 20uH below 20uH, also can reach relative accuracy and be better than 3%, can design the inductance value of measuring air core coil.The linear graph of the data representation of table 3 as shown in Figure 7
Table 3 inductance reading value L and error
| L(uH) | Lr(uH) | err | Err％ | L(uH) | Lr(uH) | err | Err％ |
| 961.5 | 987.0 | -25.5 | -2.6 | 108.2 | 115.9 | -7.7 | -0.8 |
| 710.7 | 701.5 | -26.0 | -2.6 | 99.3 | 99.9 | -0.6 | -0.1 |
| 484.7 | 510.7 | 9.2 | 0.9 | 57.0 | 59.4 | -2.4 | -0.2 |
| 386.4 | 396.8 | -10.4 | -1.0 | 19.7 | 20.3 | -0.6 | -0.1 |
| 295.2 | 304.7 | -9.5 | -0.9 | 13.3 | 13.4 | -0.1 | 0.0 |
| 206.3 | 206.0 | 0.3 | 0.0 | 6.45 | 6.32 | 0.1 | 0.0 |
Incremental mode is measured the method for small inductor value, be with the air core inductor about a 8uH as basic inductance, then connect with tested inductance, can measure the small inductor below the uH, minimum resolution is 25nH.At button of instrument face plate design, tested inductance terminal design is with basic inductance L
0With tested inductance L series wiring.When tested inductance L during by short circuit, click button, the basic inductance value that instrument will be at this moment is as relative zero 0=L-L
0, get rid of the numerical value drift of instrument.Then access tested inductance L, instrument is with incremental portion Δ L=L-L
0, show.The inductance value of measuring like this is more accurate than the measuring method of not deducting basic inductance value.In the measurement of 25nH to the air-core inductance between the uH, electric bridge has also had the phenomenon of drift.Here adopt square relation that is directly proportional with inductance of coil turn to verify.
Enameled wire coiling diameter with diameter 0.7 is the coil of 40mm, and the number of turn is respectively 2,4,6,8 circles, the basic inductance value L of measurement
0The N that=8.605uH is corresponding
TDValue N
0=270, measurement data is as shown in table 4.From interpretation of result, be the duplicate ratio that Δ N=13 (corresponding inductance value be 0.325uH) just relatively meets the number of turn during 2 circle, illustrate less than the reading of the 2 circle coils of 1uH bigger than normal.
The relation of table 4 incremental inductance reading and the number of turn
| N (circle) | L(uH) | NtD | N0 | ΔN | Multiple |
| 2 | 0.350 | 286 | 270 | 16 | 1 |
| 4 | 1.350 | 324 | 270 | 54 | 4 |
| 6 | 3.200 | 398 | 270 | 128 | 9 |
| 8 | 5.000 | 470 | 270 | 200 | 16 |
This incremental inductance value measurement method can be used for measuring inductance value, inductance type transducer and the pcb board inductance value of air-core inductance.
Relatively find in the measurement with the inductance of pcb board inductance and thin wire coiling.The resistance of copper cash can affect the survey measurements value.When copper hindered less than 1 ohm, survey measurements was normal, and when the copper resistance was larger, such as 7 ohm, the inductance reading value of measurement was less than normal.For the inductor that power supply is used, electric current is large, and the resistance of wire copper is all very little, and the utility model can both guarantee measuring accuracy.
The ARM single-chip microcomputer output control of the control system of single-chip microcomputer discharges and recharges signal, receives stable discharging signal and Timing measurement t
D, the output display data receive push button signalling.Electronic switch transistor and driving thereof and electrical level matching circuit, amplification comparison and selection discharge signal circuit etc.Show all related datas of screen display: basic inductance value L
0, inductance value L, incremental inductance Δ L=L-L
0, the timing ga(u)ge numerical value Nt during the stable discharging
DA unique button is to determine current L as L on the panel
0
The utility model can be measured the inductance value of the inductor that Power Management Design uses and the inductance value of air core coil, and precision is better than 3%.Satisfy the requirement of practical application.
The method of this inductance measuring value and electric capacity are irrelevant, also do not have the high frequency sinusoidal excitation signal, only have the electric current at 5ms interval to discharge and recharge pulse signal.
The inductor thin for enameled wire, that copper cash resistance is large, reading is less than normal.
Start needed preheating 10 minutes.
The precision and stability of measuring the incremental inductance value is relevant with the precision of metering circuit and constant current source, also needs to improve the inductance value that the circuit precision of other links could reliable measurements nH level.
When measuring electric capacity, select to change the range of measuring electric capacity between the Io=30uA-1mA, can measure the electric capacity between the 10pF-10uF.
Claims (7)
1. based on the inductance and capacitance measureing instruments of on-off circuit, it comprises inductance measurement circuit (1), capacitance measurement circuit (2), single-chip computer control system (3), display (4), keyboard circuit (5) and power circuit (6);
The inductance measurement signal input output end of inductance measurement circuit (1) is connected with the inductance measurement signal input output end of single-chip computer control system (3), the capacitance measurement signal input output end of capacitance measurement circuit (2) is connected with the capacitance measurement signal input output end of single-chip computer control system (3), the display output terminal of single-chip computer control system (3) is connected with the display input end of display (4), and the keyboard signal output terminal of keyboard circuit (5) is connected with the keyboard signal input end of single-chip computer control system (3);
Power circuit (6) is that inductance measurement circuit (1), capacitance measurement circuit (2), single-chip computer control system (3), display (4) and keyboard circuit (5) provide working power.
2. the inductance and capacitance measureing instruments based on on-off circuit according to claim 1 is characterized in that,
Described inductance measurement circuit (1) comprises current source (8), the first diode (D1), the second diode (D2), the first electronic switching circuit (9), the second electronic switching circuit (10), the 3rd electronic switching circuit (11) and quadrielectron on-off circuit (12);
The current output terminal of current source (8) is connected with an end of the first electronic switching circuit (9) and an end of the 3rd electronic switching circuit (11) simultaneously, the other end of the first electronic switching circuit (9) simultaneously with the negative electrode of the first diode (D1) be connected an end of electronic switching circuit (10) and be connected afterwards as a tested inductance incoming end, the other end while of the 3rd electronic switching circuit (11) is connected rear as another tested inductance incoming end with an end of the negative electrode of the second diode (D2) and quadrielectron on-off circuit (12), the other end of the second electronic switching circuit (10), the other end of quadrielectron on-off circuit (12), the anode of the anode of the first diode (D1) and the second diode (D2) connects the power supply ground of power supply VCC simultaneously; The negative electrode of the first diode (D1) is connected with the first signal input end of single-chip computer control system (3), the first control signal output terminal of single-chip computer control system (3) is connected with the switch control end of the first electronic switching circuit (9), the second control signal output terminal of single-chip computer control system (3) is connected with the switch control end of the second electronic switching circuit (10), the 3rd control signal output terminal of single-chip computer control system (3) is connected with the switch control end of the 3rd electronic switching circuit (11), and the 4th control signal output terminal of single-chip computer control system (3) is connected with the switch control end of quadrielectron on-off circuit (12).
3. the inductance and capacitance measureing instruments based on on-off circuit according to claim 2 is characterized in that,
Described current source (8) comprises resistance R 1, resistance R 2, resistance R 3, resistance R 4, adjustable resistance VR1 and P channel MOS tube (Q1);
One end of resistance R 1 and an end of resistance R 4 link together as the power supply end of current source (1), the end of the other end while contact resistance R2 of resistance R 1 and the adjustable end of adjustable resistance VR1, the other end of resistance R 4 is connected with the source electrode of P channel MOS tube (Q1), the stiff end of adjustable resistance VR1 is the other end, the grid of P raceway groove M0S pipe (Q1) and the end of resistance R 3 of contact resistance R2 simultaneously, the power supply ground of another termination power supply of resistance R 3, the drain electrode of P channel MOS tube (Q1) is the current output terminal of current source (1).
4. inductance and capacitance measureing instruments based on on-off circuit according to claim 2, it is characterized in that, described the first electronic switching circuit (9), the second electronic switching circuit (10), the 3rd electronic switching circuit (11) and quadrielectron on-off circuit (12) form identical, and described the first electronic switching circuit (9) comprises resistance R 111, resistance R 121 and the first N-channel MOS pipe (Q11) and a NPN type triode (Q111);
The drain electrode of the first N-channel MOS pipe (Q11) is connected with the current output terminal of current source (8) as an end of the first electronic switching circuit (9), the grid of the first N-channel MOS pipe (Q11) is connected with an end of resistance R 111 and the collector of a NPN type triode (Q111) simultaneously, the positive pole of another termination power supply of resistance R 111, the base stage of the one NPN type triode (Q111) is connected with an end of resistance R 121, and the emitter of a NPN type triode (Q111) connects the power supply ground of power supply; The source electrode of the first N-channel MOS pipe (Q11) connects the negative electrode of the first diode (D1) as the other end of the first electronic switching circuit (9), the other end of resistance R 121 is switch control ends of the first electronic switching circuit (9).
5. inductance and capacitance measureing instruments based on on-off circuit according to claim 2, it is characterized in that, single-chip computer control system (3) comprises ARM single-chip microcomputer, resistance R 5-R9, adjustable resistance VR2, the first one-level operational amplifier (IC11), the first two-level operating amplifier (IC12), the first Sheffer stroke gate (IC13)) and the 3rd diode (D3);
The end that the negative electrode of the first diode (D1) is connected with resistance R connects, the other end of resistance R 5 is connected with the forward signal input end of the first one-level operational amplifier (IC11), the reverse signal input end of the first one-level operational amplifier (IC11) is connected with the end that an end of resistance R 6 is connected with resistance R simultaneously, the power supply ground of another termination power supply of resistance R 7, the other end of resistance R 6 simultaneously with the signal output part of the first one-level operational amplifier (IC11) be connected the reverse signal input end of two-level operating amplifier (IC12) and be connected, the forward signal input end of the first two-level operating amplifier (IC12) is connected with the sliding end of adjustable resistance VR2, one of the adjustable resistance VR2 fixing power supply ground of termination power supply, another of adjustable resistance VR2 fixedly the termination power supply negative pole, the signal output part of the first two-level operating amplifier (IC12) is connected with an end of resistance R 8, the other end while of resistance R 8 and the negative electrode of the 3rd diode (D3), one end of resistance R 9 be connected input end of Sheffer stroke gate (IC13) and connect, the anode of the other end of resistance R 9 and the 3rd diode (D3) connects the power supply ground of power supply simultaneously, another input end of the first Sheffer stroke gate (IC13) is connected with the first signal output terminal of ARM single-chip microcomputer, and the output terminal of the first Sheffer stroke gate (IC13) is connected with the signal input part of ARM single-chip microcomputer;
The 3rd signal output part of ARM single-chip microcomputer is the first control signal output terminal of single-chip computer control system (3) and is connected with the switch control end of the first electronic switching circuit (9); The 4th signal output part of ARM single-chip microcomputer is the second control signal output terminal of ARM single-chip microcomputer and is connected with the switch control end of the second electronic switching circuit (10), the 5th signal output part of ARM single-chip microcomputer is that the 3rd control signal output terminal of ARM single-chip microcomputer is connected with the switch control end of the 3rd electronic switching circuit (11), the 6th signal output part of ARM single-chip microcomputer is that the 4th control signal output terminal of ARM single-chip microcomputer is connected with the switch control end of quadrielectron on-off circuit (12), the display output terminal of ARM single-chip microcomputer is connected with the display input end of display (4), the keyboard signal output terminal of keyboard circuit (5) is connected with the keyboard signal input end of ARM single-chip microcomputer, and the capacitance measurement signal input output end of capacitance measurement circuit (2) is connected with the capacitance measurement signal input output end of ARM single-chip microcomputer.
6. inductance and capacitance measureing instruments based on on-off circuit according to claim 1, it is characterized in that, described capacitance measurement circuit (2) comprises resistance R 15-R29, the first positive-negative-positive triode (Q1), the second positive-negative-positive triode (Q7), NPN type triode (Q2-Q6), chip NE555 and electric capacity (C2);
One end of the emitter of the first positive-negative-positive triode (Q1), an end of resistance R 15 and resistance R 16 connects the positive pole of power supply VCC simultaneously, the base stage of the first positive-negative-positive triode (Q1) is connected with the end that the other end of resistance R 15 is connected with resistance R simultaneously, the collector of the first positive-negative-positive triode (Q1) is connected with an end of resistance R 19
The collector of one end of the other end of resistance R 19, resistance R 27 and the 2nd NPN type triode (Q3) connects rear link as a measured capacitance, the other end of resistance R 27 is connected with the pin 2 of chip NE555, the base stage of the base stage of the 2nd NPN type triode (Q3), the 3rd NPN type triode (Q4) connects with the end that the collector of the 3rd NPN type triode (Q4) is connected with resistance R, the positive pole of another termination power supply VCC of resistance R 20
The emitter of the 2nd NPN type triode (Q3) is connected with an end of resistance R 21, the other end of resistance R 21 is connected with the emitter of the 3rd NPN type triode (Q4) and the collector of the 4th NPN type triode (Q5), the emitter of the 4th NPN type triode (Q5) connects the power supply ground of power supply VCC, the power supply ground of this power supply VCC is as the link of another measured capacitance, the 4th NPN type triode (Q5) base stage be connected with the other end of resistance R 18;
The pin 5 of chip NE555 is connected with an end of electric capacity (C2), the other end of electric capacity (C2) and the pin of chip NE555 1 be the power supply ground of power supply VCC simultaneously, the pin 6 of chip NE555 is connected with an end of resistance R 22 and the collector of the 5th NPN type triode (Q6) simultaneously, the emitter of the 5th NPN type triode (Q6) connects the power supply ground of power supply VCC, the positive pole of another termination power supply VCC of resistance R 22, the base stage of the 5th NPN type triode (Q6) is connected with an end of resistance R 28, and the other end of resistance R 28 is connected with the capacitance measurement signal output part of single-chip computer control system (3);
The other end of resistance R 17, the end that the other end of resistance R 16 is connected with resistance R is connected with the collector of a NPN type triode (Q2) simultaneously, the emitter of the one NPN type triode (Q2) connects the power supply ground of power supply VCC, the base stage of the one NPN type triode (Q2) is connected with an end of resistance R 26, the other end of resistance R 26 simultaneously and an end of resistance R 23 be connected pin 3 with chip NE555 and be connected, the other end of resistance R 23 is connected with the end that the base stage of the second positive-negative-positive triode (Q7) is connected with resistance R simultaneously, the emitter of the other end of resistance R 24 and the second positive-negative-positive triode (Q7) connects the positive pole of power supply VCC simultaneously, the collector of the second positive-negative-positive triode (Q7) is connected with an end of resistance R 29, and the other end of resistance R 29 is connected 3 with an end of resistance R 25 with single-chip computer control system) the capacitance measurement signal input part be connected; The power supply ground of another termination power supply VCC of resistance R 25.
7. inductance and capacitance measureing instruments based on on-off circuit according to claim 1, it is characterized in that, described power circuit (6) is the power circuit with charge function, and described power circuit is exported respectively power supply-12V, power supply+12V, power supply-5V, power supply+5V and power supply ground GND.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320306160 CN203241479U (en) | 2013-05-30 | 2013-05-30 | Inductance and capacitance measuring instrument based on switching circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320306160 CN203241479U (en) | 2013-05-30 | 2013-05-30 | Inductance and capacitance measuring instrument based on switching circuit |
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| CN203241479U true CN203241479U (en) | 2013-10-16 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841712A (en) * | 2017-03-15 | 2017-06-13 | 攀枝花学院 | Electronic component measuring circuit |
| CN107561343A (en) * | 2017-09-30 | 2018-01-09 | 杰华特微电子（杭州）有限公司 | A kind of current detection circuit of on-off circuit, electric current detecting method and on-off circuit |
-
2013
- 2013-05-30 CN CN 201320306160 patent/CN203241479U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106841712A (en) * | 2017-03-15 | 2017-06-13 | 攀枝花学院 | Electronic component measuring circuit |
| CN107561343A (en) * | 2017-09-30 | 2018-01-09 | 杰华特微电子（杭州）有限公司 | A kind of current detection circuit of on-off circuit, electric current detecting method and on-off circuit |
| CN107561343B (en) * | 2017-09-30 | 2023-07-18 | 杰华特微电子股份有限公司 | Current detection circuit and current detection method of switching circuit and switching circuit |
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