CN111585532A - Load sensor signal transmitting device - Google Patents
Load sensor signal transmitting device Download PDFInfo
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- CN111585532A CN111585532A CN202010435893.8A CN202010435893A CN111585532A CN 111585532 A CN111585532 A CN 111585532A CN 202010435893 A CN202010435893 A CN 202010435893A CN 111585532 A CN111585532 A CN 111585532A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
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Abstract
The invention discloses a load sensor signal transmitting device in the technical field of sensors, which comprises an alternating current filter circuit, a zero setting circuit, a differential voltage amplifying circuit and a sampling circuit, wherein the zero setting circuit is connected to the alternating current filter circuit, the differential voltage amplifying circuit is connected to the alternating current filter circuit and the zero setting circuit, the sampling circuit is connected to the zero setting circuit and the differential voltage amplifying circuit, and the alternating current filter circuit comprises: the voltage stabilizing circuit comprises a resistor R0, an electromotive force E1, a diode D1, a capacitor C1, a three-terminal regulator U1 and a capacitor C2, wherein one end of the resistor R0 is connected to a +24V power supply, and one end of the diode D1 is connected with the other end of the resistor R0.
Description
Technical Field
The invention relates to the technical field of sensors, in particular to a load sensor signal transmitting device.
Background
The sensor is a detection device which can sense the measured information and convert the sensed information into an electric signal or other information in a required form according to a certain rule to output so as to meet the requirements of information transmission, processing, storage, display, recording, control and the like. The sensor features include: miniaturization, digitalization, intellectualization, multifunction, systematization and networking. The method is the first link for realizing automatic detection and automatic control. The existence and development of the sensor enable the object to have the senses of touch, taste, smell and the like, and the object slowly becomes alive. Generally, the sensor is classified into ten categories, i.e., a thermosensitive element, a photosensitive element, a gas-sensitive element, a force-sensitive element, a magnetic-sensitive element, a humidity-sensitive element, a sound-sensitive element, a radiation-sensitive element, a color-sensitive element, and a taste-sensitive element, according to their basic sensing functions.
The load sensor is a sensor device which measures the stress of an object by checking the load borne by a stress carrier. The load sensor can convert the pressure transmitted from the carrier into corresponding electric signals, thereby achieving the purpose of measurement.
In industrial sites, there are two problems with long distance transmission of voltage signals: firstly, voltage signals are easily interfered by noise on transmission lines; second, since the input impedance of the signal receiver is not infinite, the input current of the signal receiver may generate a voltage drop due to the line resistance of the transmission line, thereby generating a signal loss.
Disclosure of Invention
The present invention is directed to a load sensor signal transmitter, which solves the problems of the prior art that the voltage signal is easily interfered by noise on the transmission line and the input impedance of the signal receiver is not infinite, so that the input current of the signal receiver is dropped by the line resistance of the transmission line, thereby causing signal loss.
In order to achieve the purpose, the invention provides the following technical scheme: a load sensor signal transmitting device, characterized in that: the zero setting circuit is connected to the alternating current filter circuit, the differential voltage amplification is connected to the alternating current filter circuit and the zero setting circuit, and the sampling circuit is connected to the zero setting circuit and the differential voltage amplification circuit.
Preferably, the ac filter circuit includes: the voltage stabilizing circuit comprises a resistor R0, an electromotive force E1, a diode D1, a capacitor C1, a three-terminal regulator U1 and a capacitor C2, wherein one end of the resistor R0 is connected to a +24V power supply, one end of the diode D1 is connected with the other end of the resistor R0, the electromotive force E1 is connected in parallel between the resistor R0 and the diode D1, the other end of the electromotive force E1 is grounded, one end of the capacitor C1 is connected with the other end of the diode D1, the other end of the capacitor C1 is grounded, one end of the three-terminal regulator U1 is connected with the other end of the diode D1, the other end of the three-terminal regulator U1 is grounded, one end of the capacitor C2 is connected with the third end of the three-terminal regulator U1, and the other end of the capacitor C.
Preferably, the zero setting circuit includes: the resistor R1, the resistor R2 and the potentiometer POT1, wherein the potentiometer POT1 is connected between the resistor R1 and the resistor R2 in series.
Preferably, the differential voltage amplifying circuit includes: the three-terminal regulator comprises a three-terminal regulator U2, a resistor R7, a triode Q1, a resistor R3, a resistor R4, a resistor R5 and a resistor R8, wherein one end of the resistor R7 is connected to one end of the three-terminal regulator U2, one end of the triode Q1 is connected to the other end of the resistor R7, one end of the resistor R3 is connected to the other end of the three-terminal regulator U2, the resistor R4 is connected to the third end of the three-terminal regulator U2, the resistor R5 is connected between the three-terminal regulator U2 and the resistor R3 in parallel, and the resistor R8 is connected between the three-terminal regulator U2 and the resistor R4 in parallel.
Preferably, the sampling circuit includes: a potentiometer POT2 and a resistor R6, wherein the resistor R6 is connected with the potentiometer POT2 in series.
Compared with the prior art, the invention has the beneficial effects that: the invention can effectively eliminate the noise interference on the transmission line of the voltage signal and reduce the signal loss, the R1, R2 and POT1 in the converter form a zero-setting circuit, actually, the zero-setting circuit is bridged on two arms of the bridge, the bridge parameters are changed by adjusting the resistance value of the POT1, a small voltage is artificially superimposed on the output signal of the bridge, the zero current (namely no-load current) is moved upwards after V/I conversion, when the resistance value between pins 1 and 2 of the POT1 is increased, the UO + potential is increased, thereby the zero current is increased, the U2 (OP 07), R7 and Q1 (S9015) and R3, R4, R5 and R8 form a voltage differential amplifier, the closed-loop amplification of the amplifier is about 110, OP07 is a low offset operational amplifier, the input offset voltage is low, the input offset current is small, the open-loop amplification is high, and the loss and the gain has better time stability and temperature stability, because the load capacity of the integrated operational amplifier is small, in order to enhance the output current of the operational amplifier, a triode Q1 (S9015) is arranged, and S9015 is a PNP-type silicon epitaxial transistor (triode), as shown in fig. 1, point B is a base, point C is a collector, point E is an emitter, the triode is used for amplifying current, when the base voltage UB changes slightly, the base current IB changes slightly, and is controlled by the base current IB, the collector current IC changes greatly, the larger the base current IB is, the larger the collector current IC is, otherwise, the smaller the base current is, the smaller the collector current is, and the change of the collector current is controlled by the base current.
Drawings
FIG. 1 is a schematic diagram of the circuit structure of the present invention;
FIG. 2 is a schematic diagram of the sensor and zero setting circuit connection of the present invention.
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.
The invention provides a load sensor signal transmitting device which can effectively eliminate the interference of noise on a voltage signal on a transmission line and reduce the signal loss;
referring to fig. 1-2, the apparatus includes an ac filter circuit, a zeroing circuit, a differential voltage amplifying circuit and a sampling circuit, wherein the zeroing circuit is connected to the ac filter circuit, the differential voltage amplifying circuit is connected to the ac filter circuit and the zeroing circuit, and the sampling circuit is connected to the zeroing circuit and the differential voltage amplifying circuit;
the AC filter circuit includes: one end of a resistor R0, an electromotive force E1, a diode D1, a capacitor C1, a three-terminal regulator U1 and a capacitor C2 is connected to a +24V power supply, one end of a diode D1 is connected with the other end of a resistor R0, an electromotive force E1 is connected between the resistor R0 and the diode D1 in parallel, the other end of the electromotive force E1 is grounded, one end of a capacitor C1 is connected with the other end of a diode D1, the other end of the capacitor C1 is grounded, one end of the three-terminal regulator U1 is connected with the other end of the diode D1, the other end of the capacitor C1 is grounded, the resistor R1 and the electromotive force E1 form an alternating current filter circuit, the diode D1 is a protection diode arranged for preventing reverse connection of power supply voltage +24V, the capacitor C1 and the capacitor C1 are input and output filter capacitors of the three-terminal regulator U1, and the working power supply of the transmitter is a direct current V power supply, the power supply is provided by the outside (such as an instrument), the power supply outputs direct current 12V through a three-terminal regulator U1 (7812) for the use of a transmitter and a load sensor, and the working current of the power supply is about 51 mA;
the zero setting circuit includes: the resistor R1, the resistor R2 and the potentiometer POT1, wherein the potentiometer POT1 is connected between the resistor R1 and the resistor R2 in series;
the differential voltage amplifying circuit includes: the three-terminal regulator U2, a resistor R7, a triode Q1, a resistor R3, a resistor R4, a resistor R5 and a resistor R8, wherein one end of a resistor R7 is connected to one end of a three-terminal regulator U2, one end of a triode Q1 is connected to the other end of a resistor R7, one end of a resistor R3 is connected to the other end of a three-terminal regulator U2, a resistor R2 is connected to the third end of the three-terminal regulator U2, the resistor R2 is connected between the three-terminal regulator U2 and the resistor R2 in parallel, the three-terminal regulator U2, the resistor R2, the triode Q2, the resistor R2 and the resistor R2 form a differential voltage amplifier, the voltage amplification factor of which is;
the sampling circuit includes: the potentiometer POT2 and the resistor R6, the resistor R6 and the potentiometer POT2 are connected in series, and the potentiometer POT2 (100 omega) and the resistor R6 are sampling resistors;
external wiring, as shown in FIG. 1, pins 1 and 2 of transmitter plug P1 are connected to the positive and negative terminals, respectively, of the sensor voltage signal output, and pins 3 and 4 are connected to the positive and negative terminals, respectively, of the sensor bridge voltage + 12V. The 1 st pin of the plug P2 is the output end of a 4-20 mA current signal of the transmitter, and the 2 nd pin and the 3 rd pin are respectively connected with the positive end and the negative end of an external power supply + 24V.
In particular, the sensor is actually an electric bridge (within the dashed box in fig. 2), the bridge arm resistance R of the sensor is 700 Ω, the input resistance and the output resistance of the sensor are both 700 Ω, the output signal is Uo when there is no resistive load at the output end of the sensor, R1, R2, and POT1 in the converter constitute a zero-adjusting circuit, actually, the zero-adjusting circuit is connected across the two arms of the electric bridge (see fig. 2), the bridge parameters are changed by adjusting the resistance of POT1, a small voltage is artificially superimposed on the output signal of the electric bridge, the zero current (i.e. no-load current) is moved up after V/I conversion, when the resistance between pins 1-2 of POT1 is increased, the Uo + potential is increased, so that the zero current is increased, U2 (07), R7, Q1 (S15), R3, R4, R5, and R8 constitute a voltage differential amplifier, the closed-loop amplification factor of the amplifier is about 110, and 07 is a low OP detuning operational amplifier, the input offset voltage is low, the input bias current is small, the open loop gain is high, and the offset and gain have better time stability and temperature stability;
voltage amplification formula of closed loop amplifier
The amplifier is a differential voltage amplifier of a double-loop semi-feedback type, the output voltage reference point is the cathode of a diode D2 (1N 4148),
let the voltage input of the transmitter be Vi, the voltage output be Vo (i.e., the voltage at R6, POT 2),
has Vi ═ e (AIN1 + -AIN 1-)
Then Vo Vi 109.7Vi 110Vi
The main parameters of OP07 are:
bias current 7000 PpA; gain bandwidth product GB =600 kHz;
the consumed current is 2.5 mA; power consumption is 500 mW;
increasing the load capacity of an amplifier
Because the load capacity of the integrated operational amplifier is small, in order to enhance the output current of the operational amplifier, a triode Q1 (S9015) is arranged, the S9015 is a PNP type silicon epitaxial transistor (triode), as shown in FIG. 1, the point B is a base, the point C is a collector, the point E is an emitter, the triode is used for amplifying current, when the base voltage UB has a slight change, the base current IB has a small change and is controlled by the base current IB, the collector current IC has a large change, the larger the base current IB is, the larger the collector current IC is, otherwise, the smaller the base current is, the smaller the collector current is, namely the base current controls the change of the collector current, and the triode has the current amplification effect because the change of the collector current is much larger than the change of the base current;
formula of current output
R6, POT2 (100 omega) together constitute a sampling resistor, wherein POT2 is used for current gain adjustment,
setting the current output of the 4-20 mA transmitter as Io,
with Io ≈ approximately ≈
It can be seen that when the input voltage is constant, the output current varies with the change in the resistance of the potentiometer POT2, and the current increases as the resistance of the potentiometer decreases,
debugging preparation: selecting and welding a resistor R6 according to the variation delta Uo of the no-load and full-load signals of the sensor (see a comparison table of the variation delta Uo of the no-load and full-load signals of the sensor and the sampling resistor R6 of the transmitter):
if Δ Uo < 5mV, R6 ═ 10 Ω;
if 5mV is less than or equal to delta UO < 10mV, R6 is 20 omega;
if 10V is less than or equal to delta UO, and less than or equal to 20mV, R6 is 43 omega;
if 20V is less than or equal to delta UO and less than or equal to 30mV, R6 is 100 omega;
first step, device connection
Connecting a 4-20 mA current transmitter with a load sensor, a +24V power supply and an output ammeter, checking the correctness of the connection, then, electrifying to check whether the working voltage of each element of the transmitter is normal, and debugging can be carried out only under the condition that the external connection is correct and the working voltage of each element of the transmitter is normal;
second, coarse adjustment of the no-load current of 4mA
And adjusting the output current of the transmitter to be 4mA under the condition that the load sensor is unloaded. If the output current is not 4mA, adjusting the POT1 potentiometer (clockwise rotation output current is reduced, and vice versa is increased) to make the output current about 3.98 mA;
third, coarse adjustment of full load current 20mA
The load sensor is slowly loaded, and the output current is gradually increased at the moment. The output current should be 20mA when added to full load. If the output is not 20mA, adjusting the potentiometer POT2 (clockwise rotation output current becomes larger, and vice versa, the output current decreases, and the adjusting direction of the zero-setting potentiometer is opposite), so that the output current value is about 20 mA;
step four, fine adjustment of no-load current 4mA
And (4) slowly unloading the load sensor, stabilizing for a while after unloading, and observing whether the 4mA changes. If the stabilized value is larger than 4mA, the current is adjusted to be larger, at this time, POT2 is adjusted counterclockwise for half a turn, and POT1 is adjusted clockwise to enable the output value to be about 4 mA;
if the stabilized value is less than 4mA, the current is adjusted to be small, at this time, POT2 is adjusted clockwise for half a turn, and POT1 is adjusted counterclockwise to enable the output value to be about 4 mA;
step five, fine adjustment of full load current 20mA
Slowly loading the load sensor again, checking and adjusting by 20mA after full load is added, and the steps are the same as the third step;
sixth step, recheck
After the unloading is adjusted, the change of 4mA is observed to judge the adjusting effect. If the 4mA does not meet the requirement, the number of turn-adjusting turns of the POT2 is determined according to the last adjustment, and the POT1 is adjusted to enable the output value to be about 4 mA;
the fourth step and the fifth step are repeated for several times, and the potentiometers for adjusting zero and gain are adjusted to be matched;
and seventhly, after the adjustment is finished, performing loading and unloading tests and recording measured data, wherein the test is performed at least three times, and the following table is shown:
eighthly, sealing the glue to fix the adjustable potentiometers POT1 and POT2 after the test is finished and the error is within the allowable range;
ninth, after the glue is dried, assembling a shell, fixing an input line and an output line, performing waterproof and moistureproof treatment, and labeling;
and step ten, before warehousing, performing a power-on loading test again, recording the measured data and archiving.
While the invention has been described above with reference to an embodiment, various modifications may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the various features of the embodiments disclosed herein may be used in any combination, provided that there is no structural conflict, and the combinations are not exhaustively described in this specification merely for the sake of brevity and conservation of resources. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (5)
1. A load sensor signal transmitting device, characterized in that: the zero setting circuit is connected to the alternating current filter circuit, the differential voltage amplification is connected to the alternating current filter circuit and the zero setting circuit, and the sampling circuit is connected to the zero setting circuit and the differential voltage amplification circuit.
2. The load sensor signal transmitter according to claim 1, wherein: the alternating current filter circuit includes: the voltage stabilizing circuit comprises a resistor R0, an electromotive force E1, a diode D1, a capacitor C1, a three-terminal regulator U1 and a capacitor C2, wherein one end of the resistor R0 is connected to a +24V power supply, one end of the diode D1 is connected with the other end of the resistor R0, the electromotive force E1 is connected in parallel between the resistor R0 and the diode D1, the other end of the electromotive force E1 is grounded, one end of the capacitor C1 is connected with the other end of the diode D1, the other end of the capacitor C1 is grounded, one end of the three-terminal regulator U1 is connected with the other end of the diode D1, the other end of the three-terminal regulator U1 is grounded, one end of the capacitor C2 is connected with the third end of the three-terminal regulator U1, and the other end of the capacitor C.
3. The load sensor signal transmitter according to claim 1, wherein: the zero setting circuit includes: the resistor R1, the resistor R2 and the potentiometer POT1, wherein the potentiometer POT1 is connected between the resistor R1 and the resistor R2 in series.
4. The load sensor signal transmitter according to claim 1, wherein: the differential voltage amplifying circuit includes: the three-terminal regulator comprises a three-terminal regulator U2, a resistor R7, a triode Q1, a resistor R3, a resistor R4, a resistor R5 and a resistor R8, wherein one end of the resistor R7 is connected to one end of the three-terminal regulator U2, one end of the triode Q1 is connected to the other end of the resistor R7, one end of the resistor R3 is connected to the other end of the three-terminal regulator U2, the resistor R4 is connected to the third end of the three-terminal regulator U2, the resistor R5 is connected between the three-terminal regulator U2 and the resistor R3 in parallel, and the resistor R8 is connected between the three-terminal regulator U2 and the resistor R4 in parallel.
5. The load sensor signal transmitter according to claim 1, wherein: the sampling circuit includes: a potentiometer POT2 and a resistor R6, wherein the resistor R6 is connected with the potentiometer POT2 in series.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010435893.8A CN111585532A (en) | 2020-05-21 | 2020-05-21 | Load sensor signal transmitting device |
| CN202010805319.7A CN111726098B (en) | 2020-05-21 | 2020-08-12 | Signal transmitting device of load sensor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010435893.8A CN111585532A (en) | 2020-05-21 | 2020-05-21 | Load sensor signal transmitting device |
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| CN111585532A true CN111585532A (en) | 2020-08-25 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010435893.8A Pending CN111585532A (en) | 2020-05-21 | 2020-05-21 | Load sensor signal transmitting device |
| CN202010805319.7A Active CN111726098B (en) | 2020-05-21 | 2020-08-12 | Signal transmitting device of load sensor |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202010805319.7A Active CN111726098B (en) | 2020-05-21 | 2020-08-12 | Signal transmitting device of load sensor |
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Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4066786B2 (en) * | 2001-12-28 | 2008-03-26 | 株式会社村田製作所 | Mechanical quantity sensor |
| US6653895B1 (en) * | 2002-06-12 | 2003-11-25 | Texas Instruments Incorporated | Gain-boost nulling amplifier for auto-zero circuit |
| CN202119578U (en) * | 2011-05-17 | 2012-01-18 | 蚌埠赛英电子科技发展有限公司 | Belt-type beam-pumping unit digital output load sensor |
| JP5983493B2 (en) * | 2013-03-26 | 2016-08-31 | 株式会社デンソー | Pressure sensor |
| CN104897946A (en) * | 2014-03-07 | 2015-09-09 | 珠海格力电器股份有限公司 | Current detection device and system |
| DE102017111197A1 (en) * | 2017-05-23 | 2018-11-29 | Sicoya Gmbh | Transimpedance amplifier circuit |
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2020
- 2020-05-21 CN CN202010435893.8A patent/CN111585532A/en active Pending
- 2020-08-12 CN CN202010805319.7A patent/CN111726098B/en active Active
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| CN111726098A (en) | 2020-09-29 |
| CN111726098B (en) | 2024-04-09 |
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