CN206330931U - A kind of electrochemical sensor modulate circuit - Google Patents
A kind of electrochemical sensor modulate circuit Download PDFInfo
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- CN206330931U CN206330931U CN201621483815.0U CN201621483815U CN206330931U CN 206330931 U CN206330931 U CN 206330931U CN 201621483815 U CN201621483815 U CN 201621483815U CN 206330931 U CN206330931 U CN 206330931U
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Abstract
The utility model is related to a kind of electrochemical sensor modulate circuit, including the current signal acquisition process circuit and voltage x current conversion circuit for connecting electrochemical sensor, also string is provided with zeroing circuit between current signal acquisition process circuit and voltage x current conversion circuit；Zeroing circuit includes zeroing operational amplifier, the in-phase input end connection current signal acquisition process circuit of zeroing operational amplifier, the inverting input of zeroing operational amplifier is provided with a series connection bleeder circuit, provided with a potentiometer in series connection bleeder circuit, the inverting input of zeroing operational amplifier connects the output end of potentiometer.The utility model sets a zeroing circuit by being gone here and there in modulate circuit, the range of transmitter is adjusted within the specific limits, to adapt to the output of different electrochemical sensors.
Description
Technical field
The utility model is related to a kind of electrochemical sensor modulate circuit, belongs to signal processing technology field.
Background technology
In industry spot, analog current output can realize the state of remote monitoring motor operation, if the signal of collection
After conditioned it is voltage signal and carries out Long line transmission, problems with can be produced：First, because the signal of transmission is voltage letter
Number, transmission line can be easy for being disturbed by noise；Second, the distributed resistance of transmission line can produce voltage drop；3rd, existing
The operating voltage how field provides instrument amplifier is also a problem；In order to solve the above problems and avoid the shadow of correlated noise
Ring, industry spot largely transmits signal using electric current, interference is not susceptible to using current signal.
Current primary solutions：
1) amplifier adds triode modulate circuit, can directly convert voltage to the DC4-20mA perseverances exported by linear scale
Ring standard signal is flowed, reception device is delivered continuously to, cost price is low so that the cost performance of this scheme seems very high, still
It is larger by electromagnetic radiation, there is certain influence on signal output.
2) integrated chip solution, ADI companies provide a kind of electric current loop transducer driven chip, such as AD694.It will can input
Voltage conversion be electric current output；This chip is great good news for exploitation 4-20mA electric currents, and integrated circuit is anti-dry
Disturb ability strong, greatly enhance the stability of signal.
But, existing modulate circuit is not suitable for the electrochemical sensor of different types of toxic and harmful gas mostly.
For different types of electrochemical sensor, it is necessary to customize special modulate circuit.
Utility model content
The purpose of this utility model is to provide a kind of electrochemical sensor modulate circuit, for solving for different types of
Electrochemical sensor is, it is necessary to customize special modulate circuit this technical problem.
In order to solve the above technical problems, the utility model provides a kind of electrochemical sensor modulate circuit, including it is following
Scheme：
Scheme one：The modulate circuit includes the current signal acquisition process circuit and voltage for being used to connect electrochemical sensor
Electric current conversion circuit, also string is provided with zeroing circuit between the current signal acquisition process circuit and voltage x current conversion circuit；
The zeroing circuit includes zeroing operational amplifier, and the in-phase input end of the zeroing operational amplifier connects the current signal
Acquisition process circuit, the inverting input of the zeroing operational amplifier is provided with a series connection bleeder circuit, the series connection partial pressure
Provided with a potentiometer in circuit, the inverting input of the zeroing operational amplifier connects the output end of the potentiometer.
Scheme two：On the basis of scheme one, the in-phase input end of the zeroing operational amplifier is additionally provided with low pass filtered
Wave circuit.
Scheme three, four：Respectively on the basis of scheme one, two, the current signal acquisition process circuit is adopted including one
Sample resistance, the sampling resistor is used for the induction electrode for connecting electrochemical sensor.
Scheme five, six：Respectively on the basis of scheme three, four, the current signal acquisition process circuit also includes one
Protection circuit for protecting electrochemical sensor, the protection circuit includes a FET and protection operational amplifier；
The drain electrode of the FET is used for the reference electrode for connecting electrochemical sensor, and the source electrode of the FET is used to connect electricity
The induction electrode of chemical sensor, the grid of the FET is used to connect triggering power supply；The protection operational amplifier
In-phase input end is used to connect reference voltage, and the inverting input of the protection operational amplifier is used to connect electrochemical sensor
Reference electrode, the output end of the protection operational amplifier be used to connecting electrochemical sensor to electrode.
Scheme seven, eight：Respectively on the basis of scheme three, four, the current signal acquisition process circuit also includes one
Electric current turns voltage operational amplifier, and the in-phase input end that the electric current turns voltage operational amplifier is used to connect reference voltage, institute
State electric current and turn the inverting input of voltage operational amplifier and be connected with the sampling resistor, the electric current turns voltage operational amplifier
Output end connection it is described zeroing operational amplifier in-phase input end.
Scheme nine, ten：Respectively on the basis of scheme one, two, the voltage x current conversion circuit includes follower circuit
And normal voltage current converter circuit；The follower circuit includes a follower, the input connection of the follower
The output end of the zeroing operational amplifier, the output end of the follower connects the normal voltage current converter circuit.
The beneficial effects of the utility model are：
A zeroing circuit is set by being gone here and there in modulate circuit, the range of transmitter is adjusted within the specific limits,
To adapt to the output of different electrochemical sensors.
Further, electrochemical sensor is protected by setting a protection circuit, while reducing electrochemistry
The stabilization time of sensor.
Further, a follower circuit is set by being gone here and there before normal voltage current converter circuit, it is to avoid front end electricity
High damage rear class device is pressed through, while improving the driving force of signal.
Brief description of the drawings
Fig. 1 is the integrated circuit structure chart of modulate circuit；
Fig. 2 is the circuit structure diagram of current signal acquisition process circuit；
Fig. 3 is the circuit structure diagram of zeroing circuit；
Fig. 4 is the circuit structure diagram of voltage x current conversion circuit；
Fig. 5 is the circuit structure diagram of the power supply circuit of modulate circuit.
Embodiment
Below in conjunction with the accompanying drawings and the utility model is described in detail specific embodiment.
The integrated circuit structure chart of electrochemical sensor modulate circuit is as shown in figure 1, the modulate circuit includes current signal
Acquisition process circuit, zeroing circuit, voltage x current conversion circuit and power supply circuit.Wherein, at the current signal collection
The input of reason circuit is connected with electrochemical sensor P1, the output end of current signal acquisition process circuit and zeroing circuit it is defeated
Enter end be connected, the output end of zeroing circuit is connected with the input of voltage x current conversion circuit, voltage x current conversion circuit it is defeated
Going out end is used to connect a plug-in unit P2.Wherein D1, D2 are plug-in unit P2 counnter attack connection interface.
In the present embodiment, electrochemical sensor P1 may be selected to be model：NH3/MR-100、H2/C-2000、CO/CF-
1000th, the electrochemical sensor such as SO2-D4, H2S-AE.Wherein, electrochemical sensor principle is as follows：
Electrochemical sensor to tested gas by reacting and producing the electric signal being directly proportional to gas concentration come work
Make.Typical electrochemical sensor is made up of sensing electrode (or working electrode) and counterelectrode, and is separated by a thin electrolyte layers.
Gas is reacted by small hollow billet type perforate with sensor first, followed by hydrophobic barrier layer, most Zhongdao
Up to electrode surface.Proper amount of gas can be allowed to be reacted with sensing electrode in this way, to form sufficient electric signal,
Prevent that electrolyte from spilling sensor simultaneously.
The gas spread through barrier reacts with sensing electrode, and sensing electrode can use oxidation mechanism or reducing machine
Reason.These reactions for the electrode material for being tested gas and designing by being catalyzed.
By the resistor connected between electrode, the electric current being directly proportional to tested gas concentration can flow between positive pole and negative pole.
Measure the electric current and can determine that gas concentration.Due to that can produce electric current during this, electrochemical sensor is commonly referred to as electric current again
Gas sensor or micro fuel cell.
In practice, because electrode surface recurs electro-chemical reaction, sensing electrode potential can not keep constant, in warp
Cross after one section of long period, it can cause sensor performance to be degenerated.To improve sensor performance, people introduce reference electrode.
Reference electrode is installed in the electrolyte, neighbouring with sensing electrode.Fixed stable permanent potential acts on sensing electrode.
Reference electrode can keep this fixed voltage value on sensing electrode.There is no electric current flowing between reference electrode.Gas molecule with
Sensing electrode reacts, while measuring counterelectrode, measurement result is generally directly related with gas concentration.Put on sensing electrode
Magnitude of voltage can make sensor be directed to object gas.
Each sub-circuit in the modulate circuit is described in detail below.
1) current signal acquisition process circuit
The circuit structure diagram of current signal acquisition process circuit is as shown in Fig. 2 the circuit is made up of two parts, the first half
Point be the protection circuit of electrochemical sensor, mainly by FET Q2 (SST177) and operational amplifier U1A (OPA4336) with
And capacitance resistance composition.Wherein, U1A in-phase input end is by resistance R3 and R19 the connection 2.5V reference voltages that are connected in series,
U1A inverting input by the reference electrode REF for the resistance R1 and R2 connection electrochemical sensor P1 being connected in series, U1A's
Output end is connected with electrochemical sensor P1 to electrode CE.Also, bridged between U1A output end and R1 and R2 tie point
There is electric capacity C1 (100nf), bridging has electric capacity C2 (10nf) between U1A output end and inverting input.Resistance R3 and R19 company
Contact is connected by electric capacity C13 with electrochemical sensor P1 induction electrode SE.FET Q2 drain electrode and electrochemical sensing
Device P1 reference electrode REF is connected, and FET Q2 source electrode is connected with electrochemical sensor P1 induction electrode SE, field-effect
The triggering power supply that pipe Q2 grid passes through resistance R6 connections 5V.
Above-mentioned protection circuit main purpose is, during the switch Q2 conductings of scene effect pipe, operational amplifier U1A have one it is small
Bias voltage, it is ensured that serious bias does not occur for electrochemical sensor, and Q2 serves protection sensor P1 effect, and makes electrification
Sensor P1 stabilization times after short circuit shorten.Q1 is connected state under normality, and Q1 disconnects in the energized state.
The amplifying circuit that Fig. 2 the latter half is made up of amplifier U1B, U1B inverting input passes through sampling resistor R5
Connection electrochemical sensor P1 induction electrode SE is sampled, and U1B in-phase input end is referred to by resistance R7 connections 2.5V
Voltage.The amplifying circuit that the current signal collected by sampling resistor R5 is constituted through U1B by the faint current signal of sensor into
Hundreds times or thousand times voltage signal is enlarged into, and is exported to next stage.
2) zeroing circuit
The circuit structure diagram of zeroing circuit is as shown in figure 3, the zeroing circuit is main by zeroing operational amplifier U1C and one
Bleeder circuit is constituted.Zeroing operational amplifier U1C in-phase input end connection current signal acquisition process circuit, zeroing computing is put
Big device U1C inverting input is provided with a series connection bleeder circuit, and the series connection bleeder circuit is by 2.5V reference voltages, potentiometer
W2, resistance R9 and R10 are in series, zeroing operational amplifier U1C inverting input connection potentiometer W2 output end.Zeroing
The two ends that resistance R17, R17 are also in series between operational amplifier U1C inverting input and output end are parallel with electric capacity C6.
In addition, being additionally provided with one between zeroing operational amplifier U1C in-phase input end and current signal acquisition process circuit
Individual low-pass filter circuit, the low-pass filter circuit is made up of resistance R8 with electric capacity C5, the high frequency letter for filtering amplifier U1B outputs
Number.Now, zeroing operational amplifier U1C is input to by the low frequency signal of current signal acquisition process circuit output, by changing
Potentiometer W2 resistance, is adjusted to the range of signal, finally causes signal inversion and output of returning to zero.
3) voltage x current conversion circuit
The circuit structure diagram of voltage x current conversion circuit is as shown in figure 4, the circuit is made up of two parts up and down, top half
The follower being individually composed by amplifier U3, the signal exported by zeroing circuit is exported through the follower, make signal by
Influence it is smaller, improve the antijamming capability of signal.The latter half of the circuit is to turn current module by AD694 voltages
Preferred circuit.Because the preferred circuit belongs to prior art, here is omitted.
4) power supply circuit
The circuit structure diagram of the power supply circuit of modulate circuit is as shown in figure 5, be Q1 by LM2936 voltage conversion chips
+ 24V power supplies are converted into+5V system voltages, then+5V is generated into 2.5V reference voltages through LM336.
The model of the specific connection line of each certain above-mentioned sub-circuit and the device of selection is only as a kind of specific
Embodiment, on the premise of identical function is realized, can also carry out suitably adjust or replace.
The operation principle of above-mentioned modulate circuit is as follows：
The protection circuit of electrochemical sensor is protected to electrochemical sensor P1, prevents that sensor from occurring serious bias
Phenomenon.The low current signal of electrochemical sensor P1 induction electrode SE outputs passes through the amplifying circuit being made up of amplifier U1B
Voltage signal is converted to, the voltage signal is input to zeroing circuit, range is adjusted within the specific limits.After being adjusted
Voltage signal be input to the follower being made up of amplifier U3 and carry out pressure limiting, damage rear class device to prevent that front voltage is too high,
The driving force of voltage signal is improved simultaneously.The voltage signal exported by follower turns current circuit into specialized voltages, most
The range swithching of sensor is exported for 4-20mA electric currents at last, and finally the electric current of the 4-20mA is exported by plug-in unit or directly.
Claims (6)
1. a kind of electrochemical sensor modulate circuit, including for connecting the current signal acquisition process circuit of electrochemical sensor
With voltage x current conversion circuit, it is characterised in that between the current signal acquisition process circuit and voltage x current conversion circuit
Also string is provided with zeroing circuit；The zeroing circuit includes zeroing operational amplifier, the homophase input of the zeroing operational amplifier
The end connection current signal acquisition process circuit, the inverting input of the zeroing operational amplifier is provided with a series connection partial pressure
Provided with a potentiometer in circuit, the series connection bleeder circuit, the inverting input connection of the zeroing operational amplifier is described
The output end of potentiometer.
2. electrochemical sensor modulate circuit according to claim 1, it is characterised in that the zeroing operational amplifier
In-phase input end is additionally provided with low-pass filter circuit.
3. electrochemical sensor modulate circuit according to claim 1 or 2, it is characterised in that the current signal collection
Process circuit includes a sampling resistor, and the sampling resistor is used for the induction electrode for connecting electrochemical sensor.
4. electrochemical sensor modulate circuit according to claim 3, it is characterised in that the current signal acquisition process
Circuit also includes a protection circuit for being used to protect electrochemical sensor, and the protection circuit includes a FET and guarantor
Protect operational amplifier；The drain electrode of the FET is used for the reference electrode for connecting electrochemical sensor, the FET
Source electrode is used for the induction electrode for connecting electrochemical sensor, and the grid of the FET is used to connect triggering power supply；It is described to protect
The in-phase input end of shield operational amplifier is used to connect reference voltage, and the inverting input of the protection operational amplifier is used to connect
Connect the reference electrode of electrochemical sensor, the output end of the protection operational amplifier be used to connecting electrochemical sensor to electricity
Pole.
5. electrochemical sensor modulate circuit according to claim 3, it is characterised in that the current signal acquisition process
Circuit also turns voltage operational amplifier including an electric current, and the in-phase input end that the electric current turns voltage operational amplifier is used to connect
Reference voltage is connect, the inverting input that the electric current turns voltage operational amplifier is connected with the sampling resistor, the electric current turns
The in-phase input end of the output end connection zeroing operational amplifier of voltage operational amplifier.
6. electrochemical sensor modulate circuit according to claim 1 or 2, it is characterised in that the voltage x current conversion
Circuit includes follower circuit and normal voltage current converter circuit；The follower circuit includes a follower, described
The output end of the input connection zeroing operational amplifier of follower, the output end of the follower connects the standard electric
Current voltage change-over circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621483815.0U CN206330931U (en) | 2016-12-30 | 2016-12-30 | A kind of electrochemical sensor modulate circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201621483815.0U CN206330931U (en) | 2016-12-30 | 2016-12-30 | A kind of electrochemical sensor modulate circuit |
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| Publication Number | Publication Date |
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| CN206330931U true CN206330931U (en) | 2017-07-14 |
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| CN201621483815.0U Active CN206330931U (en) | 2016-12-30 | 2016-12-30 | A kind of electrochemical sensor modulate circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110988089A (en) * | 2019-12-16 | 2020-04-10 | 江西农业大学 | Wide-range digital electrochemical analysis device and detection method |
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- 2016-12-30 CN CN201621483815.0U patent/CN206330931U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110988089A (en) * | 2019-12-16 | 2020-04-10 | 江西农业大学 | Wide-range digital electrochemical analysis device and detection method |
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