CN103439581A - Measuring circuit - Google Patents
Measuring circuit Download PDFInfo
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- CN103439581A CN103439581A CN201310384808XA CN201310384808A CN103439581A CN 103439581 A CN103439581 A CN 103439581A CN 201310384808X A CN201310384808X A CN 201310384808XA CN 201310384808 A CN201310384808 A CN 201310384808A CN 103439581 A CN103439581 A CN 103439581A
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- electric capacity
- effect transistor
- field effect
- voltage divider
- output terminal
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Abstract
The invention discloses a measuring circuit which comprises a signal source, a voltage divider, a measuring loop and a millivoltmeter. The input end of the voltage divider is connected with the output end of the signal source, the output end of the voltage divider is connected with the input end of the measuring loop, and the output end of the measuring loop is connected with the millivoltmeter. Materials needed by the measuring circuit can be found everywhere, the measuring circuit is simple to manufacture, low in cost and suitable for people, especially students, who need to compare the magnitude of impedances with low impedance measurement accuracy requirements. Further, the measuring circuit is stable in performance.
Description
Technical field
The present invention relates to a kind of metering circuit, particularly for the circuit of impedance measurement.
Background technology
At present, the multiple range impedance measuring Instrument of multi-usage, can be in order to characteristic impedance of effective parallel connection of the high-frequency dielectric loss of the electric capacity of the inductance value of the Q value of measuring high-frequency inductor or resonant tank, inductor and distributed electrical capacity, capacitor and loss angle, electrical material, radio circuit and resistance in series, transmission line etc.Although, but current impedance measuring Instrument Q table precision is high, it is expensive, applicable crowd is narrower, and popularity rate is low, and particularly for students, when being tested, needed surveying instrument accuracy requirement is not high, unable the bearing but dutiable value is expensive.
Therefore need a kind of new technical scheme to solve the problems referred to above.
Summary of the invention
Goal of the invention: the problem and shortage existed for above-mentioned prior art, the purpose of this invention is to provide a kind of metering circuit, its cost is low, stable performance.
Technical scheme: the technical solution used in the present invention is a kind of metering circuit, comprise signal source, measuring circuit and voltage divider, the input end of voltage divider is connected with the output terminal of signal source, and the output terminal of this voltage divider is connected with the input end of measuring circuit, and the output terminal of measuring circuit is connected with milivoltmeter; The 5th electric capacity of voltage divider (all in parallel to the 14 electric capacity, then link with an end of the 4th electric capacity; Described signal source consists of the LC oscillation circuit, the first inductance and the second Capacitance parallel connection, the one side is ground connection simultaneously, opposite side is connected with the grid of field effect transistor, the source electrode of field effect transistor is connected with the input end of two-stage common-base amplifier, and the output terminal of two-stage common-base amplifier is connected with the grid of field effect transistor.
LC does shunt-resonant circuit as a whole, and side while ground connection, be easy to starting of oscillation, and oscillation amplitude is stable, and insensitive to device parameter values, waveform is good, and the vibration range of adjustment is wide, and the amplitude versus frequency characte of regulating oscillating capacitance is steady.
Preferably, the two-stage common-base amplifier is comprised of triode, and the emitter of the first triode is connected with the source electrode of field effect transistor, and its collector is connected with the emitter of the second triode, and the collector of the second triode is connected with the grid of field effect transistor.。
Preferably, the output terminal that the source electrode of field effect transistor is signal source, the other end of the 4th electric capacity is connected with the source electrode of field effect transistor.
Preferably, the capacitance of the 5th electric capacity to the 14 electric capacity is identical, and the capacitance of the 4th electric capacity is 1/10th of the 5th electric capacity.
Beneficial effect: compared with prior art, its advantage is that material required for the present invention can be looked for everywhere in the present invention, and makes simple, cost is low, applicable accurately little to impedance measurement, but needs the relatively crowd of impedance magnitude to use, User particularly, stable performance of the present invention.
The accompanying drawing explanation
Fig. 1 is structural representation of the present invention;
Fig. 2 is the signal source circuit figure of invention;
Fig. 3 is integrated circuit figure of the present invention.
Embodiment
As shown in Figure 1, this circuit of the present invention comprises signal source, measuring circuit and voltage divider, the input end of described voltage divider is connected with the output terminal of signal source, and the output terminal of this voltage divider is connected with the input end of measuring circuit, and the output terminal of described measuring circuit is connected with milivoltmeter;
As shown in Figure 2, signal source consists of the LC oscillation circuit, the first inductance L 1 and the second capacitor C 2 parallel connections, the one side is ground connection simultaneously, opposite side is connected with the grid of field effect transistor Q1, the source electrode of field effect transistor Q1 is connected with the input end of two-stage common-base amplifier, and the output terminal of two-stage common-base amplifier is connected with the grid of field effect transistor Q1; The two-stage common-base amplifier is comprised of triode, and the emitter of the first triode Q3 is connected with the source electrode of field effect transistor Q1, and its collector is connected with the emitter of the second triode Q2, and the collector of the second triode Q2 is connected with the grid of field effect transistor Q1
As shown in Figure 3, the 5th capacitor C 5 to the 14 capacitor C 14 of voltage divider are all in parallel, then link with an end of the 4th capacitor C 4; The output terminal that the source electrode of field effect transistor Q1 is signal source, the other end of the 4th capacitor C 4 is connected with the source electrode of field effect transistor Q1; The 5th capacitor C 5 is identical to the capacitance of the 14 capacitor C 14, and the capacitance of the 4th capacitor C 4 is 1/10th of the 5th capacitor C 5.
The other end of the 5th capacitor C 5 accesses tested inductance L
xan end, tested inductance L
xthe other end with an end of variable capacitance, be connected, the other end ground connection of variable capacitance, measured capacitance C
xin parallel with variable capacitance.
Output same frequency in fixed signal source is with the sinusoidal signal of amplitude, and milivoltmeter can be converted by voltage table, and resistance value is output voltage and input voltage ratio.
Material required for the present invention can be looked for everywhere, and making is simple, and cost is low, applicable accurately little to impedance measurement, but needs relatively the crowd use, particularly User of impedance magnitude, stable performance of the present invention.
Claims (4)
1. a metering circuit, it is characterized in that: this circuit comprises signal source, measuring circuit and voltage divider, the input end of described voltage divider is connected with the output terminal of signal source, and the output terminal of this voltage divider is connected with the input end of measuring circuit, and the output terminal of described measuring circuit is connected with milivoltmeter; The 5th electric capacity (C5) of described voltage divider is all in parallel to the 14 electric capacity (C14), then links with an end of the 4th electric capacity (C4); Described signal source consists of the LC oscillation circuit, the first inductance (L1) and the second electric capacity (C2) parallel connection, the one side is ground connection simultaneously, opposite side is connected with the grid of field effect transistor (Q1), the source electrode of field effect transistor (Q1) is connected with the input end of two-stage common-base amplifier, and the output terminal of two-stage common-base amplifier is connected with the grid of field effect transistor (Q1).
2. a kind of metering circuit according to claim 1, it is characterized in that: described two-stage common-base amplifier is comprised of triode, the emitter of the first triode (Q3) is connected with the source electrode of field effect transistor (Q1), its collector is connected with the emitter of the second triode (Q2), and the collector of the second triode (Q2) is connected with the grid of field effect transistor (Q1).
3. a kind of metering circuit according to claim 1, it is characterized in that: the output terminal that the source electrode of field effect transistor (Q1) is signal source, the other end of the 4th electric capacity (C4) is connected with the source electrode of field effect transistor (Q1).
4. a kind of metering circuit according to claim 1, it is characterized in that: the 5th electric capacity (C5) is identical to the capacitance of the 14 electric capacity (C14), and the capacitance of the 4th electric capacity (C4) is 1/10th of the 5th electric capacity (C5).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310384808.XA CN103439581B (en) | 2013-08-30 | 2013-08-30 | A kind of metering circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310384808.XA CN103439581B (en) | 2013-08-30 | 2013-08-30 | A kind of metering circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103439581A true CN103439581A (en) | 2013-12-11 |
| CN103439581B CN103439581B (en) | 2016-06-01 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310384808.XA Active CN103439581B (en) | 2013-08-30 | 2013-08-30 | A kind of metering circuit |
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| CN (1) | CN103439581B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3648165A (en) * | 1970-09-24 | 1972-03-07 | Sun Oil Co | Capacitance-measuring apparatus including means maintaining the voltage across the unknown capacitance constant |
| CN86102187A (en) * | 1986-04-01 | 1987-10-21 | 湖北省计量测试研究所 | High frequency inducdtance and capacitance measuring instrument |
| CN102253286A (en) * | 2011-06-27 | 2011-11-23 | 郑军 | Resistance/capacitance measuring method and device thereof |
| CN102636701A (en) * | 2012-04-17 | 2012-08-15 | 深南电路有限公司 | Inductor detecting instrument and method |
-
2013
- 2013-08-30 CN CN201310384808.XA patent/CN103439581B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3648165A (en) * | 1970-09-24 | 1972-03-07 | Sun Oil Co | Capacitance-measuring apparatus including means maintaining the voltage across the unknown capacitance constant |
| CN86102187A (en) * | 1986-04-01 | 1987-10-21 | 湖北省计量测试研究所 | High frequency inducdtance and capacitance measuring instrument |
| CN102253286A (en) * | 2011-06-27 | 2011-11-23 | 郑军 | Resistance/capacitance measuring method and device thereof |
| CN102636701A (en) * | 2012-04-17 | 2012-08-15 | 深南电路有限公司 | Inductor detecting instrument and method |
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| Publication number | Publication date |
|---|---|
| CN103439581B (en) | 2016-06-01 |
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