CN202994876U - Micro-signal acquisition card - Google Patents
Micro-signal acquisition card Download PDFInfo
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- CN202994876U CN202994876U CN 201220749245 CN201220749245U CN202994876U CN 202994876 U CN202994876 U CN 202994876U CN 201220749245 CN201220749245 CN 201220749245 CN 201220749245 U CN201220749245 U CN 201220749245U CN 202994876 U CN202994876 U CN 202994876U
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Abstract
The utility model relates to a micro-signal acquisition card, comprising a function commutation circuit, a current source circuit, a signal conditioning circuit, a current sampling circuit, a signal acquiring and processing circuit and a communication interface circuit. An end of the function commutation circuit is connected with a terminal HI, a grounding terminal L, a terminal HS, a terminal LS, a terminal I, the current source circuit and the current sampling circuit. The other end of the function commutation circuit is connected with the signal conditioning circuit, the signal acquiring and processing circuit and the communication interface circuit in sequence. The terminal HI and the grounding terminal L form a voltage acquisition terminal. The terminal HS and the terminal LS form a resistor acquisition terminal. The grounding terminal L and the terminal I form a current acquisition terminal and a current source output terminal. The micro-signal acquisition card solves technical problems that an existing micro-signal acquisition card has low sampling speed and precision is not high. The micro-signal acquisition card enables high precision measurement of normal signals, and has a high-dynamic range. The micro-signal acquisition card provides functions of acquiring and measuring microhm, nanoampere, and nanovolt signals.
Description
Technical field
The utility model belongs to the fields such as thermometrically, instrument and meter, signal condition.
Background technology
The present characteristics that collection ubiquity sampling rate is low, precision is not high for tiny signal, along with developing rapidly of modern science and technology, especially in fields such as Aero-Space, oil well logging, automatic controls, the collection signal amplitude is more and more less, and acquisition precision requires more and more higher.In this case, the high-precision tiny signal capture card of exploitation has good engineering application.The measurement function of this capture card can fully satisfy the tiny signal collection for the output of the sensors such as pressure, strain, temperature, vibration.
Summary of the invention
In order to solve the existing technical matters that tiny signal capture card sampling rate is low, precision is not high, the utility model provides a kind of tiny signal capture card, the utility model can be realized the high-acruracy survey for normal signal, have high dynamic range, can provide simultaneously for micro-ohm, Na An and receive collection, the measurement function of vor signal.
Technical solution of the present utility model:
The tiny signal capture card, its special character is: comprise function commutation circuit, current source circuit, signal conditioning circuit, current sampling circuit, signal acquisition processing circuit and communication interface circuit,
One end of described function commutation circuit is connected with terminal HI, ground terminal L, terminal HS, terminal LS, terminal I, current source circuit and current sampling circuit, the other end of described function commutation circuit is connected with signal conditioning circuit, signal acquisition processing circuit and communication interface circuit successively
Described terminal HI, the L shaped one-tenth voltage acquisition of ground terminal end, described terminal HS and terminal LS form the electrical resistance collection end, and described ground terminal L and terminal I form current acquisition end and current source output terminal,
Described current source circuit process function commutation circuit provides the constant current source excitation to the measured resistance at electrical resistance collection end place; Described current sampling circuit passes through function commutation circuit acquisition stream through the tested electric current of current acquisition end,
Described signal conditioning circuit is converted into voltage signal through the function commutation circuit with measured resistance, electric current, and is transferred to signal conditioning circuit and carries out signal and amplify or attenuation processing.
the above-mentioned functions commutation circuit comprises K switch 1, K switch 2, K switch 3 and four is selected an analog switch K4, one end of described K switch 2 is connected with terminal HI, the other end of described K switch 2 divides two-way, one the tunnel is connected with current source circuit through K switch 1, another Lu Yusi selects the contact A of an analog switch K4 to connect, terminal I is through K switch 3, select the contact B of an analog switch K4 to be connected with four after current sampling circuit, terminal HS and four selects the contact C of an analog switch K4 to be connected, terminal LS and four selects the contact D of an analog switch K4 to be connected, four select the contact of an analog switch K4 to be connected with signal conditioning circuit.
Above-mentioned current source circuit comprises clamping circuit, current-limiting circuit, Gear Select Switch J1-J14, and the feedback output circuit, described current-limiting circuit comprises current-limiting resistance R4-R10, described current-limiting resistance R4-R10 one end is in parallel.
Described clamping circuit comprises the first operational amplifier U1B, field effect transistor Q1, voltage stabilizing diode D2, resistance R 1, resistance R 2, and described feedback output circuit comprises the second operational amplifier U1A, voltage stabilizing diode D1 and resistance R 3,
The positive pole of described the first operational amplifier U1B connects the 5V power supply, the negative pole of described the first operational amplifier U1B is by resistance R 2 ground connection, the grid of the output termination FET Q1 of described the first operational amplifier U1B, the source electrode connecting resistance R2 of described FET Q1, the drain electrode of described FET Q1 divides two-way, one tunnel is connected with an end of resistance R 1, another road is connected with the positive pole of the second operational amplifier U1A, the other end of described resistance R 1 divides two-way, the Zener diode D2 of leading up to is connected with power supply, the other end is connected with an end of current-limiting circuit
The other end of the resistance R 4 of described current-limiting circuit divides two-way, the Gear Select Switch J1 of leading up to is connected with the negative pole of the second operational amplifier U1A, another road is connected with the drain electrode of field effect transistor Q2 by Gear Select Switch J8, the connected mode of the other end of the resistance R 5-R10 of described current-limiting circuit is identical with resistance R 4
The output terminal of described the second operational amplifier U1A is connected with an end of resistance R 3 by voltage stabilizing diode D1, and the grid of described field effect transistor Q2 is connected with an end of resistance R 3, and the other end of described resistance R 3 is connected with power supply.
Above-mentioned signal conditioning circuit comprises the 3rd operational amplifier U1C, four-operational amplifier U1D, the 5th operational amplifier U1E, the 6th operational amplifier U1F, resistance R 11-R19 and resistance R
ref, the minus earth of described the 3rd operational amplifier, the positive pole of described the 3rd operational amplifier, resistance R
refAn end and an end of resistance R 12 connect, an end of the other end of the output terminal of described the 3rd operational amplifier, resistance R 12 and resistance R 14 connects,
The negative pole of described four-operational amplifier U1D, resistance R 11 and resistance R
refThe other end connect, an end of the other end of the output terminal of described four-operational amplifier U1D, resistance R 11 and resistance R 13 connects, the positive pole of four-operational amplifier U1D meets VIN,
One end of the negative pole of the other end of described resistance R 14, the 5th operational amplifier U1E, resistance R 15 connects,
One end of one end of the positive pole of the other end of described resistance R 13, the 5th operational amplifier U1E and resistance R 16 and resistance R 19 connects,
One end of one end of the other end of the output terminal of described the 5th operational amplifier U1E, resistance R 15, resistance R 17 and resistance R 18 connects, and the other end of described resistance R 18 is as the negative pole of out-put supply,
The negative pole of the other end of the other end of described resistance R 17, resistance R 16, the 6th operational amplifier U1F connects,
The output terminal of the other end of described resistance R 19 and the 6th operational amplifier U1F is as the positive pole of out-put supply, and the positive pole of the 6th operational amplifier U1F meets difference output male model voltage V
REF
above-mentioned current sampling circuit comprises voltage stabilizing diode D3-D6, the 7th operational amplifier U1G and sampling resistor R0, the end of described sampling resistor R0, the equal ground connection of the negative electrode of the anode of voltage stabilizing diode D6 and voltage stabilizing diode D4, the other end of described sampling resistor R0, the negative electrode of voltage stabilizing diode D5 is connected anode and all is connected with the positive pole of the 7th operational amplifier U1G with voltage stabilizing diode D3, the negative electrode of described voltage stabilizing diode D3, the anode of voltage stabilizing diode D4, the anode of voltage stabilizing diode D5 is connected negative electrode and all is connected with the negative pole of the 7th operational amplifier U1G with voltage stabilizing diode D6, the output terminal of described the 7th operational amplifier U1G is connected with the negative pole of the 7th operational amplifier U1G, the positive pole of described the 7th operational amplifier U1G is as the sampling end of current sampling circuit, and the output terminal of described the 7th operational amplifier U1G is as the output terminal of current sampling circuit, and the positive pole of described the 7th operational amplifier U1G is connected with the function commutation circuit.
Above-mentioned communication interface circuit is RS232, USB or Ethernet digital interface.
The utility model has advantages of:
1, the utility model is to small resistance measurement the time, and current source has the fan-out capability of totally 9 gears from 500nA ~ 1A, and the resistance measurement scope is from 10 microhms ~ 10M ohm, and the precision of measurement is high.
2, signal conditioning circuit of the present utility model adopts improved magnifier, has greatly reduced the impact of analog switch conducting resistance for gain.
3, the current sampling circuit of the utility model optimization, reduce leakage current to the impact of acquisition precision, and current measuring range is from 10nA ~ 3A.
4, the purpose of this utility model is to realize the high-acruracy survey for normal signal (resistance, voltage, electric current), has high dynamic range, provides for micro-ohm, Na An and receives collection, the measurement function of vor signal.
Description of drawings
Fig. 1 is the principle schematic of the utility model tiny signal capture card;
Fig. 2 is the utility model function commutation circuit structural drawing;
Fig. 3 is the utility model current source circuit schematic diagram;
Fig. 4 is the utility model signal acquisition processing circuit schematic diagram;
Fig. 5 is the utility model current sampling circuit schematic diagram.
Embodiment
As shown in Figure 1, the tiny signal capture card comprises current source circuit, signal conditioning circuit, current sampling circuit, signal acquisition processing circuit and communication interface circuit.Fig. 1 is the structured flowchart of tiny signal capture card.HI and L are voltage acquisition, two line resistance collections and current source lead-out terminal; HS and LS are that four-wire ohm gathers terminal; I and L are the current acquisition terminal.
Current source circuit provides constant current source that detected element (resistance) is encouraged when being used for resistance measurement.
When current sampling circuit is used for current measurement, tested electric current is sampled.
The function commutation circuit realizes the function switching of resistance, voltage, current measurement, and measured resistance, electric current are converted into voltage signal, is transferred to signal conditioning circuit and carries out the signal amplification or decay to rational scope.
The analog to digital that signal acquisition processing circuit carries out voltage signal transforms, and carries out digital low-pass filtering, is converted into actual measured value.Analog to digital transforms to adopt has 24 resolving power chips, and actual effectively resolving power can reach 21, and sampling rate is program control adjustable from 6.8Hz ~ 3.5KHz.
Communication interface circuit is mainly realized RS232, USB, and the digital interface such as Ethernet.
The function commutation circuit as shown in Figure 2, by K switch 1, K2, K3, K4 forms.K1, K2, K3 are the single-pole single-throw (SPST) relay, K4 four selects an analog switch.K1, K2, K3, the different switching states of K4 have just realized the measurement function of resistance, voltage, electric current.
Four-wire ohm illustrates:
The current source circuit output current, through K2, the K1 relay measurand of flowing through flows back to integrated circuit board through L.K4 relay C contact adhesive gathers a side magnitude of voltage, and then K4 relay D contact adhesive gathers the opposite side magnitude of voltage, and it is poor that two values are done, and can calculate the current source measurand pressure drop afterwards of flowing through, and according to formula R=V/I, can calculate resistance value.
Table 1 function is selected the closure state table with switch
Current source circuit has the fan-out capability of totally 9 gears from 500nA ~ 1A.Figure is that current source is realized the principal diagram intention, can output current be 1uA ~ 1A.Operational amplifier U1B with the voltage clamping at R7 two ends at 5V, the electric current that flows through R2 is 1mA, because R1 is equal with the R2 resistance, therefore the voltage at R1 two ends is also 5V, according to the empty short principle of operational amplifier, when the J1 adhesive, the voltage at R4 two ends is also 5V, the electric current that flow through R4 this moment is 1A, the principle disconnected according to the void of operational amplifier, and the 1A electric current is exported through Q2 when the J8 adhesive.Table 2 has been described the relation of electric current output with the switch closure.
The output of table 2 electric current and switch occluding relation table
Signal conditioning circuit adopts improved magnifier, and this design is done following improvement to the magnifier of routine:
Change gain control circuit, eliminate the analog switch conducting resistance to gain effects.
Be difference output with the magnifier output transform, be conducive to improve modulus conversion chip to the precision of signals collecting.
The conventional instrument amplifying circuit generally, the gain feedback resistance control to be switched by analog switch, analog switch conducting resistance R
onBe tens of ohms, when gain feedback resistance R3 is hundred ohm or more hour, the conducting resistance of analog switch on gain accuracy impact can not eliminate.
As shown in Figure 4, change-over switch J1, J2 are placed on backfeed loop, disconnected principle empty according to operational amplifier, the electric current that flows through switch J1, J2 is zero, thereby eliminates the impact of analog switch.U1E and U1F are converted into differential signal with output signal.
Suppose R1=R2=4=R5=R6=R7=R8=R9=R10=R, when J1, J2 are closed simultaneously:
Current sampling circuit adds the operational amplifier feedback circuit, the leakage current that causes to reduce D1 ~ D4.Circuit design as shown in Figure 6, D3 ~ D6 is overvoltage crowbar, R0 is current sampling resistor, comes Flow to cross the electric current of R0 by the voltage that gathers R0 two ends.Short principle empty according to operational amplifier, making the voltage at D5 and D6 two ends is zero, thereby has limited to greatest extent leakage current, has guaranteed receiving the collection of peace level electric current.
Claims (6)
1. the tiny signal capture card, comprise function commutation circuit, current source circuit, signal conditioning circuit, current sampling circuit, signal acquisition processing circuit and communication interface circuit,
One end of described function commutation circuit is connected with terminal HI, ground terminal L, terminal HS, terminal LS, terminal I, current source circuit and current sampling circuit, the other end of described function commutation circuit is connected with signal conditioning circuit, signal acquisition processing circuit and communication interface circuit successively
Described terminal HI, the L shaped one-tenth voltage acquisition of ground terminal end, described terminal HS and terminal LS form the electrical resistance collection end, and described ground terminal L and terminal I form current acquisition end and current source output terminal,
Described current source circuit process function commutation circuit provides the constant current source excitation to the measured resistance at electrical resistance collection end place; Described current sampling circuit passes through function commutation circuit acquisition stream through the tested electric current of current acquisition end,
Described signal conditioning circuit is converted into voltage signal through the function commutation circuit with measured resistance, electric current, and is transferred to signal conditioning circuit and carries out signal and amplify or attenuation processing.
2. tiny signal capture card according to claim 1, it is characterized in that: described function commutation circuit comprises K switch 1, K switch 2, K switch 3 and four is selected an analog switch K4, one end of described K switch 2 is connected with terminal HI, the other end of described K switch 2 divides two-way, one the tunnel is connected with current source circuit through K switch 1, another Lu Yusi selects the contact A of an analog switch K4 to connect, terminal I is through K switch 3, select the contact B of an analog switch K4 to be connected with four after current sampling circuit, terminal HS and four selects the contact C of an analog switch K4 to be connected, terminal LS and four selects the contact D of an analog switch K4 to be connected, four select the contact of an analog switch K4 to be connected with signal conditioning circuit.
3. tiny signal capture card according to claim 1 and 2 is characterized in that:
Described current source circuit comprises clamping circuit, current-limiting circuit, Gear Select Switch J1-J14, and the feedback output circuit, described current-limiting circuit comprises current-limiting resistance R4-R10, described current-limiting resistance R4-R10 one end is in parallel,
Described clamping circuit comprises the first operational amplifier U1B, field effect transistor Q1, voltage stabilizing diode D2, resistance R 1, resistance R 2, and described feedback output circuit comprises the second operational amplifier U1A, voltage stabilizing diode D1 and resistance R 3,
The positive pole of described the first operational amplifier U1B connects the 5V power supply, the negative pole of described the first operational amplifier U1B is by resistance R 2 ground connection, the grid of the output termination FET Q1 of described the first operational amplifier U1B, the source electrode connecting resistance R2 of described FET Q1, the drain electrode of described FET Q1 divides two-way, one tunnel is connected with an end of resistance R 1, another road is connected with the positive pole of the second operational amplifier U1A, the other end of described resistance R 1 divides two-way, the Zener diode D2 of leading up to is connected with power supply, the other end is connected with an end of current-limiting circuit
The other end of the resistance R 4 of described current-limiting circuit divides two-way, the Gear Select Switch J1 of leading up to is connected with the negative pole of the second operational amplifier U1A, another road is connected with the drain electrode of field effect transistor Q2 by Gear Select Switch J8, the connected mode of the other end of the resistance R 5-R10 of described current-limiting circuit is identical with resistance R 4
The output terminal of described the second operational amplifier U1A is connected with an end of resistance R 3 by voltage stabilizing diode D1, and the grid of described field effect transistor Q2 is connected with an end of resistance R 3, and the other end of described resistance R 3 is connected with power supply.
4. tiny signal capture card according to claim 3, it is characterized in that: described signal conditioning circuit comprises the 3rd operational amplifier U1C, four-operational amplifier U1D, the 5th operational amplifier U1E, the 6th operational amplifier U1F, resistance R 11-R19 and resistance R ref, the minus earth of described the 3rd operational amplifier, the positive pole of described the 3rd operational amplifier, one end of the end of resistance R ref and resistance R 12 connects, the output terminal of described the 3rd operational amplifier, one end of the other end of resistance R 12 and resistance R 14 connects
The other end of the negative pole of described four-operational amplifier U1D, resistance R 11 and resistance R ref connects, and an end of the other end of the output terminal of described four-operational amplifier U1D, resistance R 11 and resistance R 13 connects, and the positive pole of four-operational amplifier U1D meets VIN,
One end of the negative pole of the other end of described resistance R 14, the 5th operational amplifier U1E, resistance R 15 connects,
One end of one end of the positive pole of the other end of described resistance R 13, the 5th operational amplifier U1E and resistance R 16 and resistance R 19 connects,
One end of one end of the other end of the output terminal of described the 5th operational amplifier U1E, resistance R 15, resistance R 17 and resistance R 18 connects, and the other end of described resistance R 18 is as the negative pole of out-put supply,
The negative pole of the other end of the other end of described resistance R 17, resistance R 16, the 6th operational amplifier U1F connects,
The output terminal of the other end of described resistance R 19 and the 6th operational amplifier U1F is as the positive pole of out-put supply, and the positive pole of the 6th operational amplifier U1F meets difference output male model voltage VREF.
5. tiny signal capture card according to claim 4, it is characterized in that: described current sampling circuit comprises voltage stabilizing diode D3-D6, the 7th operational amplifier U1G and sampling resistor R0, the end of described sampling resistor R0, the equal ground connection of the negative electrode of the anode of voltage stabilizing diode D6 and voltage stabilizing diode D4, the other end of described sampling resistor R0, the negative electrode of voltage stabilizing diode D5 is connected anode and all is connected with the positive pole of the 7th operational amplifier U1G with voltage stabilizing diode D3, the negative electrode of described voltage stabilizing diode D3, the anode of voltage stabilizing diode D4, the anode of voltage stabilizing diode D5 is connected negative electrode and all is connected with the negative pole of the 7th operational amplifier U1G with voltage stabilizing diode D6, the output terminal of described the 7th operational amplifier U1G is connected with the negative pole of the 7th operational amplifier U1G, the positive pole of described the 7th operational amplifier U1G is as the sampling end of current sampling circuit, and the output terminal of described the 7th operational amplifier U1G is as the output terminal of current sampling circuit, and the positive pole of described the 7th operational amplifier U1G is connected with the function commutation circuit.
6. tiny signal capture card according to claim 5, it is characterized in that: described communication interface circuit is RS232, USB or Ethernet digital interface.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220749245 CN202994876U (en) | 2012-12-30 | 2012-12-30 | Micro-signal acquisition card |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220749245 CN202994876U (en) | 2012-12-30 | 2012-12-30 | Micro-signal acquisition card |
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|---|---|
| CN202994876U true CN202994876U (en) | 2013-06-12 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220749245 Withdrawn - After Issue CN202994876U (en) | 2012-12-30 | 2012-12-30 | Micro-signal acquisition card |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103076480A (en) * | 2012-12-30 | 2013-05-01 | 陕西海泰电子有限责任公司 | Tiny signal collecting card |
| CN110687334A (en) * | 2019-10-09 | 2020-01-14 | 中国南方电网有限责任公司超高压输电公司柳州局 | Relay protection error-proof digital multimeter |
-
2012
- 2012-12-30 CN CN 201220749245 patent/CN202994876U/en not_active Withdrawn - After Issue
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103076480A (en) * | 2012-12-30 | 2013-05-01 | 陕西海泰电子有限责任公司 | Tiny signal collecting card |
| CN103076480B (en) * | 2012-12-30 | 2015-06-10 | 陕西海泰电子有限责任公司 | Tiny signal collecting card |
| CN110687334A (en) * | 2019-10-09 | 2020-01-14 | 中国南方电网有限责任公司超高压输电公司柳州局 | Relay protection error-proof digital multimeter |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20130612 Effective date of abandoning: 20150610 |
|
| RGAV | Abandon patent right to avoid regrant |