CN207559950U - A kind of pH value sensor signal amplifying circuit - Google Patents
A kind of pH value sensor signal amplifying circuit Download PDFInfo
- Publication number
- CN207559950U CN207559950U CN201721800897.1U CN201721800897U CN207559950U CN 207559950 U CN207559950 U CN 207559950U CN 201721800897 U CN201721800897 U CN 201721800897U CN 207559950 U CN207559950 U CN 207559950U
- Authority
- CN
- China
- Prior art keywords
- resistance
- dual
- gate field
- effect pipe
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Abstract
The utility model provides a kind of pH value sensor signal amplifying circuit, is amplified for the output signal to PH sensor.The circuit is using N-channel depletion type dual-gate field-effect pipe as core element, it is aided with three fixed resistances and a variable resistance, realize the amplification of the output voltage signal (polarity of voltage or positive or negative or be zero) of pH value sensor, and the acid-base value of amplified voltage signal and measured medium is in good linear relationship.Compared with traditional processing circuit, the utility model has many advantages, such as simple and reliable, good linearity, at low cost.It can be widely applied to the amplification of the output signal of various pH value sensors and input voltage be just or be negative, and require occasion of the amplification output for positive signal.
Description
Technical field
The utility model is related to a kind of hardware circuit, more particularly to a kind of no matter input voltage is just or is negative, and output is equal
For the circuit of positive voltage, and the input and output of the circuit have good linear relationship, are particularly suitable for the output of pH value sensor
The amplification of signal.
Background technology
Most of existing pH value sensor is all direct voltage output type, when measured medium is neutral, output electricity
Pressure is zero；When measured medium is in acidity, output voltage is negative value；When measured medium is in alkalinity, output voltage is then for just
Value.For the uncertain d. c. voltage signal of this polarity of voltage, conventional method usually according to the following steps discriminates signal
Other places are managed, i.e., first the polarity of input signal are screened with voltage comparator, then again with general purpose instrument amplifying circuit to letter
It number is amplified, and signed magnitude arithmetic(al) is carried out to signal, finally converting thereof into digital signal by A/D conversions again is for control
System processing.Digital signal, which will also be aided with signal polarity mark, could correctly judge pH value.Not only processing circuit is complicated for the above method,
And cost is higher, and inconvenience is all brought to design and use.
Utility model content
The purpose of this utility model is to provide a kind of pH value sensor signal amplification being made of discrete component, inexpensive
Circuit, for that both may be pH value that positive polarity d. c. voltage signal may also be negative polarity d. c voltage signal to output signal
The amplification of the output signal of sensor.
The technical solution of the present invention is to provide a kind of pH value sensor signal amplifying circuit, is characterized in that：
Including sensor output equivalent circuit, dual-gate field-effect pipe, dual-gate field-effect pipe transconductance curve control circuit, bigrid field
Effect pipe biasing circuit and output circuit；
The output terminal of the sensor output equivalent circuit is connect with one of grid of dual-gate field-effect pipe；
Dual-gate field-effect pipe transconductance curve control circuit includes a termination electricity of resistance R1 and resistance R2, above-mentioned resistance R1
Source anode, the other end of resistance R1 are connect respectively with another grid of dual-gate field-effect pipe and resistance R2, and resistance R2 is direct
Ground connection；
Dual-gate field-effect pipe biasing circuit is connected on positive pole and is connect with the drain electrode of dual-gate field-effect pipe；
Above-mentioned output circuit is connected in parallel between drain electrode and the source electrode of dual-gate field-effect pipe.
Preferably, the sensor output equivalent circuit includes the voltage source being serially connected and resistance R, resistance R and double grid
One of grid connection of pole field-effect tube.
Preferably, dual-gate field-effect pipe biasing circuit includes being sequentially connected in series in the resistance R3 of positive pole and resistance R4,
Resistance R4 is connect with the drain electrode of dual-gate field-effect pipe.
Preferably, above-mentioned output circuit includes capacitance C1 in parallel and capacitance C2.
Preferably, when resistance R3 variable resistances adjustable for resistance, it can be achieved that being calibrated to the output of entire circuit.
Preferably, above-mentioned dual-gate field-effect pipe is the bigrid metal-oxide-semiconductor field effect transistor of model BF998.
Preferably, power supply 12V, R1=R2=100K.
Preferably, R3=100 Ω, R4=620 Ω.
The circuit is mainly by sensor output equivalent circuit module, dual-gate field-effect pipe mutual conductance control curve circuit, double
Gate field effect pipe biasing circuit, output calibration circuit and 5 part of output circuit composition.
Wherein sensor output equivalent circuit be according to the technical parameter of specific pH value sensor, it is equivalent using Dai Weinan
Circuit theory is reduced to the equivalent model of voltage source series resistance, is calculated in order to simplify the analysis of circuit；Bigrid field
Effect pipe mutual conductance control curve circuit then controls field-effect tube by applying different voltage to one of which grid and source electrode
Transconductance curve, to realize that the adjust automatically of amplifying circuit gain and circuit linearity adjust；Dual-gate field-effect pipe biasing circuit
Effect be then to provide suitable quiescent point for dual-gate field-effect pipe, can accurately and reliably amplify input letter
Number；Output calibration circuit is for the calibration during the zeroing and use before sensor comes into operation, to ensure sensor energy
Accurately and reliably measure；Output circuit is then to stablize the sensor output signal by amplification, and after sending into row buffering
Continuous A/D modular converters or digital processing unit handle the output of sensor.
The beneficial effects of the utility model are：
1st, the utility model uses bigrid depletion mode MOSFET the device can be operated in increasing for core element
Strong mode can be operated in depletion-mode again, to the polarity of the d. c. voltage signal of input there is no limit；
2nd, the utility model only overstates lead curve by the variation of one of which gate source voltage with regard to controllable entire field-effect tube,
To realize automatically controlling and linear adjust automatically for gain；
3rd, the utility model hardware is formed simple, at low cost, easy to maintain.
Description of the drawings
Attached drawing 1 is the structure diagram of the utility model.
Attached drawing 2 is the circuit diagram of the utility model.
Attached drawing 3 is the transconductance curve figure of certain bigrid metal-oxide-semiconductor field effect transistor.
Specific embodiment
Below in conjunction with drawings and the specific embodiments, the present invention will be further described.
As shown in Figure 2, specific work process is as described below for the circuit diagram of the utility model：
First, sensor output equivalent circuit
Since presently used pH value sensor is all direct voltage output type, and its output is all given in manufacture
Resistance.Therefore according to Thevenin's theorem, " the linear resistance one-port network containing independent current source can be equivalent to a voltage source and electricity
Hinder the one-port network of series connection ", the present embodiment can by the output equivalent of sensor for attached voltage source Vsensor shown in Fig. 2 and
Resistance Rsensor.So as to simplify the analysis to the circuit, calculated in order to carry out circuit simulation, parts selection and parameter.
2nd, transconductance curve control circuit
Attached drawing 3 show the transconductance curve of certain bigrid metal-oxide-semiconductor field effect transistor its performance plot.From the characteristic curve：
Under the same terms, gate source voltage VG2SDirectly determine the transconductance curve of field-effect tube, therefore can be by setting rational gate-source
Voltage VG2STo obtain suitable transconductance curve, and then obtain suitable direct current amplification factor.In the present embodiment, VG2SIt is by electricity
R1 and R2 is hindered as obtained from partial pressure.VG2SSpecific magnitude be then output voltage, common pH value according to pH value sensor
What several factors such as range, required amplification factor and actual power voltage codetermined.It is used in view of the utility model
The output voltage of pH value sensor be -600mv to 600mv (corresponding pH value 1 to 14), and the pH value of practical measured medium is usual
Between 5 to 9 (its corresponding sensor output voltage arrive for -200mV 200mV), with reference to bigrid metal-oxide-semiconductor field effect transistor across
Characteristic curve and the required technical indicators such as linear are led, the bigrid MOS field-effects of model BF998 are adopted in the present embodiment
Pipe, the power supply of system is 12V, VG2SStablize via after the electric resistance partial pressure of two 100k in 6V.So as to suitably be amplified
Multiple and good linear.
3rd, effect pipe biasing circuit
Bigrid metal-oxide-semiconductor field effect transistor Q1 is enable to work normally, is just necessary for its setting and the quiescent point implemented, together
When in order to make its reliably working that it must also be protected, prevent certain parameters in actual moving process from reaching its absolute rating
And it is to destroy component.The resistance value of R3 is set as by 100 Ω according to the specific electric parameter of drain electrode Q1 in the present embodiment, by R4
Resistance value be set as 620 Ω, it can be ensured that the maximum drain current that can most generate is no more than the permitted maximum electric leakage of field-effect tube
Stream, to ensure dual-gate field-effect pipe reliability service.
4th, output calibration circuit
PH value sensor belongs to measurement instrument, by calibrating or will be calibrated with during use before being taken into use, really
Same measurement criteria can be traceable to, and then ensure the pH value sensor energy of all working with other same type of sensor by protecting it
Enough there is preferable consistency and versatility.It can reach to output by adjusting the resistance value of variable resistance R3 in the present embodiment
The purpose being adjusted, principle are as follows：Due to leakage current being descended to remain unchanged under the same conditions, increase resistance R3, then R3 and
Pressure drop on R4 will increase, and so as to reduce output voltage, play the role of negative-feedback regu- lation.
5th, output circuit
The effect of output circuit is to stablize the sensor output signal by amplification, and send follow-up A/ into row buffering
D modular converters or digital processing unit handle the output of sensor.In this embodiment by capacitance C1 and C2 to putting
Big signal carries out transmitting a subsequent process circuit again after voltage regulation filtering.
Claims (8)
1. a kind of pH value sensor signal amplifying circuit, it is characterised in that：It is imitated including sensor output equivalent circuit, bigrid field
Ying Guan, dual-gate field-effect pipe transconductance curve control circuit, dual-gate field-effect pipe biasing circuit and output circuit；
The output terminal of the sensor output equivalent circuit is connect with one of grid of dual-gate field-effect pipe；
Dual-gate field-effect pipe transconductance curve control circuit includes resistance R1 and resistance R2, and a termination power of the resistance R1 is just
Pole, the other end of resistance R1 are connect respectively with another grid of dual-gate field-effect pipe and resistance R2, and resistance R2 is directly grounded；
Dual-gate field-effect pipe biasing circuit is connected on positive pole and is connect with the drain electrode of dual-gate field-effect pipe；
The output circuit is connected in parallel between drain electrode and the source electrode of dual-gate field-effect pipe.
2. pH value sensor signal amplifying circuit according to claim 1, it is characterised in that：The sensor output equivalent
Circuit includes the voltage source being serially connected and resistance R, resistance R are connect with one of grid of dual-gate field-effect pipe.
3. pH value sensor signal amplifying circuit according to claim 2, it is characterised in that：Dual-gate field-effect pipe biases
Circuit includes being sequentially connected in series in the resistance R3 of positive pole and resistance R4, and resistance R4 is connect with the drain electrode of dual-gate field-effect pipe.
4. pH value sensor signal amplifying circuit according to claim 3, it is characterised in that：The output circuit is included simultaneously
The capacitance C1 and capacitance C2 of connection.
5. pH value sensor signal amplifying circuit according to claim 4, it is characterised in that：Resistance R3 is adjustable for resistance
Variable resistance.
6. pH value sensor signal amplifying circuit according to claim 5, it is characterised in that：The dual-gate field-effect pipe
Bigrid metal-oxide-semiconductor field effect transistor for model BF998.
7. pH value sensor signal amplifying circuit according to claim 6, it is characterised in that：Power supply is 12V, R1=
R2=100K.
8. pH value sensor signal amplifying circuit according to claim 7, it is characterised in that：R3=100 Ω, R4=620
Ω。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721800897.1U CN207559950U (en) | 2017-12-20 | 2017-12-20 | A kind of pH value sensor signal amplifying circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721800897.1U CN207559950U (en) | 2017-12-20 | 2017-12-20 | A kind of pH value sensor signal amplifying circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN207559950U true CN207559950U (en) | 2018-06-29 |
Family
ID=62661068
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201721800897.1U Expired - Fee Related CN207559950U (en) | 2017-12-20 | 2017-12-20 | A kind of pH value sensor signal amplifying circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN207559950U (en) |
-
2017
- 2017-12-20 CN CN201721800897.1U patent/CN207559950U/en not_active Expired - Fee Related
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2016179964A1 (en) | Detection circuit and detection method for high-side current | |
| CN103634008B (en) | Multi-channel signal collecting device and collecting method | |
| CN105116362B (en) | A kind of oscilloscope analog front end impedance inverter circuit with program control calibration function | |
| CN103267891B (en) | Lossless current detecting circuit based on digital correction | |
| CN102879758A (en) | Standard source and detecting device both used for detecting harmonic influence quantity of electronic current transformer | |
| CN208506629U (en) | A kind of power supply circuit based on far-end feedback | |
| CN105445673A (en) | Direct-current constant-resistance electronic load apparatus | |
| CN108061823A (en) | Four electrode conductivity monitoring instrument of dynamic bipolar impulse method underground water and method | |
| CN207559950U (en) | A kind of pH value sensor signal amplifying circuit | |
| CN103973244A (en) | Current compensating circuit, current compensating method and operational amplifier | |
| CN218158096U (en) | Circuit for automatically switching current range gears based on micro-current | |
| CN105466460A (en) | Circuit temperature drift compensation system and method of biosensor | |
| CN201429424Y (en) | Differential resistance sensor detection circuit | |
| CN201788222U (en) | AC-DC (alternating current-direct current) compatible isolated voltage sampling circuit | |
| CN207515923U (en) | A kind of programmable high precision temperature compensation system | |
| CN204241537U (en) | A kind of current collection circuit | |
| CN207649766U (en) | Faint light current detection circuit | |
| CN212849984U (en) | Monitoring device for high-low voltage power transmission and distribution equipment | |
| CN207095717U (en) | A kind of temperature transmitter circuit structure | |
| CN206431454U (en) | A kind of servo-driver of AD correction coefficient self-correcting | |
| CN206878787U (en) | A kind of automatic gain control circuit | |
| CN206804043U (en) | Recording instrument without paper with multi-channel sampling | |
| CN207280674U (en) | A kind of measuring circuit of vacuum instrument | |
| CN202393814U (en) | Sampling circuit with operation amplification function | |
| CN201926940U (en) | Multi-path temperature control device for ion migration spectrometer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20180629 Termination date: 20181220 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |