1. The utility model provides a food fungus crowd short-term test device, includes signal extraction circuit, threshold value judgement circuit and the cascade amplification circuit that connects gradually, its characterized in that: the signal extraction circuit comprises an INPUT port INPUT, 2 triodes Q4 and Q7, 4 capacitors C1, C6, C10 and C12 respectively, 5 resistors R1, R2, R9, R15 and R15 respectively, wherein the INPUT port INPUT in the signal extraction circuit is connected with one end of the capacitor C15, one end of the resistor R15, one end of the capacitor C15 and one end of the resistor R15 respectively, the other end of the capacitor C15 is connected with a high-level VCC, the other end of the resistor R15 is connected with a collector of the triode Q15, the other end of the capacitor C15 is connected with a base of the triode Q15, the other end of the resistor R15 is grounded, an emitter of the triode Q15 is grounded, a collector of the triode Q15 is connected with a base of the triode Q15, one end of the resistor R15 is connected with the VCC, the other end of the resistor R15 is connected with the collector of the triode Q15, one end of the resistor R15 is connected with an emitter of the triode Q4, the other end of the resistor R15 is grounded, one end of the capacitor C12 is connected with the emitter of the triode Q4, the other end of the capacitor C12 is grounded, one end of the capacitor C1 is connected with the high-level VCC, and the other end of the capacitor C1 is grounded.

2. The device for rapidly detecting the flora in food according to claim 1, wherein: the threshold judging circuit comprises a switch S1, a bidirectional clamping diode D2, a sliding rheostat R11, 2 resistors R4 and R7, 2 transistors Q3 and Q5, 4 capacitors C2, C4, C5 and C5, wherein one end of the switch S5 in the threshold judging circuit is connected with a high level VCC, the other end of the switch S5 is connected with a collector of the transistor Q5, one end of the resistor R5 is connected with the high level VCC, the other end of the resistor R5 is connected with a base of the transistor Q5, an emitter of the transistor Q5 is grounded, a collector of the transistor Q5 is connected with a base of the transistor Q5, an emitter of the transistor Q5 is grounded, the base of the transistor Q5 is connected with one end of the resistor R5, one end of the capacitor C5, one end of the bidirectional clamping diode D5 and one end of the capacitor C5, the other end of the resistor R5 is connected with the base of the transistor Q5, the other end of the high level of the capacitor C5 is grounded, the bidirectional clamping diode D5 is connected with the high level of the high level. The other end of the capacitor C9 is connected with the sliding sheet end of the sliding rheostat R11, one end of the sliding rheostat resistor is grounded, the other end of the sliding rheostat resistor is connected with one end of the capacitor C4, the other end of the capacitor C4 is connected with the collector of the triode Q4, one end of the capacitor C2 is connected with the high-level VCC, and the other end of the capacitor C2 is grounded.

3. The device for rapidly detecting the flora in food according to claim 1, wherein: the cascade amplifying circuit comprises an amplifier U1, a variable resistor R10, a sliding rheostat R12, 8 capacitors respectively including C3, C7, C8, C11, C13, C14, C15 and C16, 7 resistors respectively including R3, R5, R6, R8, R13, R14 and R17, and 5 triodes respectively including Q1, Q2, Q3, Q6 and Q8, wherein one end of the resistor R5 of the cascade amplifying circuit is connected with a No. 2 interface of the amplifier U5, the other end of the resistor R5 is connected with a high-level VCC, a No. 3 interface of the amplifier U5 is connected with the high-level VCC, one end of the resistor R5 is connected with a No. 1 interface of the amplifier U5, the other end of the resistor R5 is connected with one end of the capacitor C5, the other end of the capacitor C5 is connected with the ground, one end of the sliding rheostat R5 is connected with the sliding rheostat 5 of the sliding rheostat 5 and the sliding rheostat 5, the other end of the resistor of the sliding rheostat R12 is connected with one end of a capacitor C8, the other end of the capacitor C8 is connected with the emitter of a triode Q3, the interface No. 4 of an amplifier U1 is respectively connected with the cathode of a diode D1 and one end of a variable resistor R10, the other end of the variable resistor R10 is connected with the base of the triode Q6, one end of a resistor R3 is connected with a high-level VCC, the other end of the resistor R3 is connected with the base of a triode Q2, the anode of the diode D1 is connected with the base of a triode Q2, one end of the capacitor C7 is connected with the base of a triode Q2, the other end of a capacitor C7 is connected with the base of a triode Q6, the collector of a triode Q2 is connected with the base of a triode Q1, the emitter of a triode Q2 is connected with the emitter of a triode Q6, the collector of a triode Q6 is connected with the base of a triode Q8, the emitter of a triode Q8 is connected with the interface No. 5 of an amplifier U1, and the collector of a triode Q8 is connected with the collector of a triode Q1, an emitter of the transistor Q1 is connected to a high-level VCC, a collector of the transistor Q1 is connected to an emitter of the transistor Q2, one end of the capacitor C13 is connected to the interface 1 of the amplifier U1, the other end of the capacitor C13 is connected to a collector of the transistor Q1, one end of the resistor R17 is connected to the interface 1 of the amplifier U1, the other end of the resistor R17 is connected to one end of the capacitor C16, the other end of the capacitor C16 is connected to a collector of the transistor Q1, one end of the resistor R6 is connected to a collector of the transistor Q1, the other end of the resistor R6 is connected to the OUTPUT port put, one end of the resistor R8 is connected to a collector of the transistor Q1, the other end of the resistor R8 is connected to one end of the capacitor C11, the other end of the capacitor C11 is connected to a collector of the transistor Q1, one end of the capacitor C3 is connected to a high-level VCC, and the other end of the capacitor C3 is grounded.

Background

Food is an energy source for human life activities, and food safety is a great public safety problem directly related to the health of people and the stability of society. The food microbiology test in China comprises three systems of total bacterial colony number, coliform group and pathogenic bacteria, wherein the coliform group is provided as an index of food polluted by excrement, and the detection condition of the group is mainly used for indicating whether the excrement pollution exists in the food, so that the method is one of important bases for the sanitation quality of poor food. Effectively controlling the number of coliform groups in the video is an important means for reducing the risk of food-borne substance poisoning. Therefore, the method is improved according to an electrical impedance measurement method, an electrical impedance measuring instrument is combined with an electronic computer, the bacterial colony in the detected liquid can be quickly detected, and meanwhile, the detection precision can be improved by utilizing a high-precision detector.

As shown in fig. 1, for a signal extraction circuit in the prior art, an amplifier U2A and an amplifier U2B are used as cores to implement two functions of signal filtering and signal amplification, but the circuit is overall complicated, signal acquisition at an input end is discontinuous, and signal extraction accuracy is poor.

As shown in fig. 2, the dynamic comparator circuit in the prior art functionally shares two parts, namely a dynamic and amplifying circuit and a comparison circuit, and uses a field effect transistor as a core transistor, and meanwhile, a large amount of capacitive filtering is adopted, so that the noise reduction is strong, the power consumption is low, however, the information intercommunity among all components is poor, and the automation degree is low.

Disclosure of Invention

Problem (A)

1. The prior art has the defects of complex operation and discontinuous sampling.

2. In the prior art, the automation degree is low.

3. The prior art has poor flexibility and low modifiable degree.

(II) technical scheme

To above-mentioned technical problem, the application provides a food fungus crowd short-term test device, including signal extraction circuit, threshold value judgement circuit and cascade amplifier circuit, specifically gather after the culture solution or the measured sample liquid internal variation resistance through the sensor, sampling signal can be at first at signal extraction circuit, carries out the preliminary treatment of signal, mainly carries out filtering and preliminary amplification. The characteristics of the capacitor and the triode are utilized. Then, the signal is inputted to the threshold judging circuit, the slide rheostat R11, the switch S1 and the resistor R12, so that the accuracy of the threshold judgment can be controlled. After being judged by a cascade triode Q5 and a triode Q3, the signals enter a section of final cascade amplifying circuit. In the module, signals are mainly amplified through an operational amplifier and a class A amplifier formed by serially connecting triodes, and are finally output through resistance-capacitance filtering, so that the anti-interference capability of the signals is improved, and the stability of the signals is kept.

And the signal extraction circuit is mainly used for detecting the internal resistance value range of the collected culture solution or the detected sample solution through an external sensor. The signal is INPUT from the INPUT terminal, then passes through the resistance-capacitance filtering circuit and is INPUT into a transistor Q7. The amplified signal is input into a common-emitter triode Q4 after being amplified by the first stage, and the signal is output to a capacitor C4 after being stabilized by the common-emitter stage.

The threshold value judging circuit can ensure that a culture solution in the culture medium has certain impedance under normal conditions, and nutrient components in the culture medium are converted into bacterial metabolism end products due to the metabolism of flora, so that the conductivity in the culture medium is increased, and the resistance is reduced. Therefore, the threshold judgment circuit can generate different judgment signals according to the transmitted resistance value range. After the primary processing of the signal in the first stage, the signal is connected to the threshold judging module through the sliding rheostat. The slide rheostat R11 is a first control point of the detection accuracy of the circuit, and the magnitude of the signal input to the threshold judgment module can be changed by changing the magnitude of the resistance. The signal is input to a switch judgment circuit of a cascade transistor Q5 and a transistor Q3 through a capacitor C9, and the signal can be accurately extracted and judged according to the value of the signal voltage, and the collector of the transistor Q3 is connected with a switch. When the switch is switched off, only one triode Q5 is connected into the circuit, the judgment precision is relatively reduced, and when the switch is switched on, a cascade switch is formed to judge the input signal. The signal is finally output to a capacitor C8 for stable filtering as the output of the module.

The cascade amplification circuit has small signal voltage generated by the front-stage threshold judgment circuit, and is very easy to be interfered in the transmission process, so that amplification output is needed. After passing through the threshold judgment circuit, the signal enters the cascade amplification circuit at the output end. First, the signal goes to the negative terminal of the operational amplifier U1 after passing through the slide rheostat R12. Meanwhile, a resistance matching network is formed by the resistor R5 and the resistor R13. And then the signals are output to a triode Q2 and a triode Q6 which form a class A amplifier for amplifying the power of the signals and further improving the anti-interference capability of the resulting signals. And finally, the output is carried out through a resistance-capacitance filter circuit.

(III) advantageous effects

A fast detection device for food flora is simple and fast to operate, and can continuously sample and test; secondly, the method is suitable for measuring the growth condition of viable bacteria in the culture medium, and has high automation degree; finally, the detection accuracy can be modified by modifying part of the circuitry in the device.

Drawings

Fig. 1 is a schematic diagram of a prior art signal extraction circuit.

Fig. 2 is a prior art dynamic comparator circuit.

Fig. 3 is a schematic circuit diagram of the present application.

Detailed Description

The present invention will be further described with reference to the following examples.

As shown in fig. 3, for this application, a fast detecting device for food flora is provided, which includes a signal extraction circuit, a threshold judgment circuit and a cascade amplification circuit, and after a sensor collects a resistance value that changes in a culture solution or a sample solution to be detected, a sampling signal is firstly subjected to preliminary processing of the signal in the signal extraction circuit, and is mainly subjected to filtering and preliminary amplification. The characteristics of the capacitor and the triode are utilized. Then, the signal is inputted to the threshold judging circuit, the slide rheostat R11, the switch S1 and the resistor R12, so that the accuracy of the threshold judgment can be controlled. After being judged by a cascade triode Q5 and a triode Q3, the signals enter a section of final cascade amplifying circuit. In the module, signals are mainly amplified through an operational amplifier and a class A amplifier formed by serially connecting triodes, and are finally output through resistance-capacitance filtering, so that the anti-interference capability of the signals is improved, and the stability of the signals is kept.

And the signal extraction circuit is mainly used for detecting the internal resistance value range of the collected culture solution or the detected sample solution through an external sensor. The signal is INPUT from the INPUT terminal, then passes through the resistance-capacitance filtering circuit and is INPUT into a transistor Q7. The amplified signal is input into a common-emitter triode Q4 after being amplified by the first stage, and the signal is output to a capacitor C4 after being stabilized by the common-emitter stage.

Specifically, the signal extraction circuit comprises an INPUT port INPUT, 2 transistors Q4, Q7, 4 capacitors C1, C6, C10, and C12, 5 resistors R1, R2, R9, R15, and R15, wherein the INPUT port INPUT is connected to one end of the capacitor C15, one end of the resistor R15, one end of the capacitor C15, and one end of the resistor R15, the other end of the capacitor C15 is connected to a high level VCC, the other end of the resistor R15 is connected to a collector of the transistor Q15, the other end of the capacitor C15 is connected to a base of the transistor Q15, the other end of the resistor R15 is connected to a ground, an emitter of the transistor Q15 is connected to a ground, a collector of the transistor Q15 is connected to a base of the transistor Q15, one end of the resistor R15 is connected to a high level VCC, and the other end of the resistor R15 is connected to a collector of the transistor Q15. One end of the resistor R15 is connected with an emitter of the triode Q4, the other end of the resistor R15 is grounded, one end of the capacitor C12 is connected with the emitter of the triode Q4, the other end of the capacitor C12 is grounded, one end of the capacitor C1 is connected with the high-level VCC, and the other end of the capacitor C1 is grounded.

The threshold value judging circuit can ensure that a culture solution in the culture medium has certain impedance under normal conditions, and nutrient components in the culture medium are converted into bacterial metabolism end products due to the metabolism of flora, so that the conductivity in the culture medium is increased, and the resistance is reduced. Therefore, the threshold judgment circuit can generate different judgment signals according to the transmitted resistance value range. After the primary processing of the signal in the first stage, the signal is connected to the threshold judging module through the sliding rheostat. The slide rheostat R11 is a first control point of the detection accuracy of the circuit, and the magnitude of the signal input to the threshold judgment module can be changed by changing the magnitude of the resistance. The signal is input to a switch judgment circuit of a cascade transistor Q5 and a transistor Q3 through a capacitor C9, and the signal can be accurately extracted and judged according to the value of the signal voltage, and the collector of the transistor Q3 is connected with a switch. When the switch is switched off, only one triode Q5 is connected into the circuit, the judgment precision is relatively reduced, and when the switch is switched on, a cascade switch is formed to judge the input signal. The signal is finally output to a capacitor C8 for stable filtering as the output of the module.

Specifically, the threshold determination circuit includes a switch S1, a bidirectional clamping diode D2, a sliding rheostat R11, 2 resistors R4, R7, 2 transistors Q3, Q5, 4 capacitors C2, C4, C5, and C9, wherein one end of the switch S1 in the threshold determination circuit is connected to a high level VCC, the other end of the switch S1 is connected to a collector of a transistor Q3, one end of the resistor R4 is connected to the high level VCC, the other end of the resistor R4 is connected to a base of a transistor Q3, an emitter of a transistor Q3 is grounded, a collector of a transistor Q5 is connected to a base of a transistor Q3, an emitter of the transistor Q5 is grounded, a base of the transistor Q5 is connected to one end of a resistor R7, one end of a capacitor C9, one end of a bidirectional clamping diode D2, and one end of a capacitor C5, the other end of the resistor R7 is connected to a base of a transistor Q3, and the other end of a capacitor C5 is connected to the high level VCC, the other end of the bidirectional clamping diode D2 is grounded, the other end of the capacitor C9 is connected with the sliding piece end of the sliding rheostat R11, one end of the sliding rheostat resistor is grounded, the other end of the sliding rheostat resistor is connected with one end of the capacitor C4, the other end of the capacitor C4 is connected with the collector of the triode Q4, one end of the capacitor C2 is connected with the high-level VCC, and the other end of the capacitor C2 is grounded.

The cascade amplification circuit has small signal voltage generated by the front-stage threshold judgment circuit, and is very easy to be interfered in the transmission process, so that amplification output is needed. After passing through the threshold judgment circuit, the signal enters the cascade amplification circuit at the output end. First, the signal goes to the negative terminal of the operational amplifier U1 after passing through the slide rheostat R12. Meanwhile, a resistance matching network is formed by the resistor R5 and the resistor R13. And then the signals are output to a triode Q2 and a triode Q6 which form a class A amplifier for amplifying the power of the signals and further improving the anti-interference capability of the resulting signals. And finally, the output is carried out through a resistance-capacitance filter circuit.

Specifically, the cascade amplifying circuit comprises an amplifier U1, a variable resistor R10, a sliding rheostat R12, 8 capacitors C3, C7, C8, C11, C13, C14, C15, C16, 7 resistors R3, R5, R6, R8, R13, R14, R17, and 5 triodes Q1, Q2, Q3, Q6, and Q8, wherein one end of the cascade amplifying circuit resistor R5 is connected to the No. 2 interface of the amplifier U5, the other end of the resistor R5 is connected to the high level VCC, the No. 3 interface of the amplifier U5 is connected to the high level VCC, one end of the resistor R5 is connected to the No. 1 interface of the amplifier U5, the other end of the resistor R5 is connected to one end of the capacitor C5, the other end of the capacitor C5 is connected to the ground, one end of the capacitor C5 is connected to the sliding rheostat R5, and the sliding rheostat R5 is connected to the sliding rheostat 5, the other end of the resistor of the sliding rheostat R12 is connected with one end of a capacitor C8, the other end of the capacitor C8 is connected with the emitter of a triode Q3, the interface No. 4 of an amplifier U1 is respectively connected with the cathode of a diode D1 and one end of a variable resistor R10, the other end of the variable resistor R10 is connected with the base of the triode Q6, one end of a resistor R3 is connected with a high-level VCC, the other end of the resistor R3 is connected with the base of a triode Q2, the anode of the diode D1 is connected with the base of a triode Q2, one end of the capacitor C7 is connected with the base of a triode Q2, the other end of a capacitor C7 is connected with the base of a triode Q6, the collector of a triode Q2 is connected with the base of a triode Q1, the emitter of a triode Q2 is connected with the emitter of a triode Q6, the collector of a triode Q6 is connected with the base of a triode Q8, the emitter of a triode Q8 is connected with the interface No. 5 of an amplifier U1, and the collector of a triode Q8 is connected with the collector of a triode Q1, an emitter of the transistor Q1 is connected to a high-level VCC, a collector of the transistor Q1 is connected to an emitter of the transistor Q2, one end of the capacitor C13 is connected to the interface 1 of the amplifier U1, the other end of the capacitor C13 is connected to a collector of the transistor Q1, one end of the resistor R17 is connected to the interface 1 of the amplifier U1, the other end of the resistor R17 is connected to one end of the capacitor C16, the other end of the capacitor C16 is connected to a collector of the transistor Q1, one end of the resistor R6 is connected to a collector of the transistor Q1, the other end of the resistor R6 is connected to the OUTPUT port put, one end of the resistor R8 is connected to a collector of the transistor Q1, the other end of the resistor R8 is connected to one end of the capacitor C11, the other end of the capacitor C11 is connected to a collector of the transistor Q1, one end of the capacitor C3 is connected to a high-level VCC, and the other end of the capacitor C3 is grounded.

While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.