CN2272140Y

CN2272140Y - Detector of liquid in food

Info

Publication number: CN2272140Y
Application number: CN 96243773
Authority: CN
Inventors: 解黎明
Original assignee: WUHUA NEW AND HIGH TECHNOLOGY DEV APPLICATION INST KUNMING
Current assignee: WUHUA NEW AND HIGH TECHNOLOGY DEV APPLICATION INST KUNMING
Priority date: 1996-10-22
Filing date: 1996-10-22
Publication date: 1998-01-07
Anticipated expiration: 2006-10-22

Abstract

The utility model discloses a detector of liquid in food, which analyzes other liquid content in food through testing the resistance of the food. The utility model is characterized in that a sense amplifying circuit taking a triode T< 1 > as main is adopted to enable the resistance of the food after mixed with liquid to slightly change and to be magnified by 300 to 400 times, and users can be enabled to accurately and rapidly read number. A resistance R< 1 > or R< 2 > is selected and arranged in the circuit of the utility model according to different tested food to form a detection circuit whose input impedance is high internal resistance together with a resistance R< 4 >. Potentiometers W< 1 >, W< 2 > and W< 3 > form a correcting circuit, enhancing testing accuracy, and the utility model has the advantages of simple structure, low cost and convenient carrying.

Description

The food liquid detector

The utility model relates to the portable high internal resistance resistance detection instrument that a kind of resistance by test food is analyzed other content liquid in the food.

At present, some illegal retailers join vacation on the market in food, such as: ginseng water is played tricks in food such as milk, meat, drinks, leads the consumer into a trap.People are in order to purchase when selling this based food, avoid having dust thrown into the eyes, general employing bridge type resistance monitor detects the content liquid in the food, because after mixing liquid in the food, the resistance variations of food is less, detect with this bridge type resistance monitor, its shown result is not obvious, can't be from table pin-point reading.In addition, because electric current that this type of detector is surveyed is greater than milliampere (mA level), sensor can make the food catalysis that produces electrolysis during measurement in very short time, thereby makes measuring accuracy be subjected to very big influence, truth often differs greatly with test result, is difficult to satisfy user's requirement.

The purpose of this utility model provides a kind of high internal resistance low current (uA level) that possesses simultaneously, little error, high precision, and energy is quick, accurate reading, food liquid detector easy to carry.

The technical scheme that the utility model adopted is:

This food liquid detector is made up of probe, instrument case and testing circuit.Testing circuit is to be divided into directed mu balanced circuit, sensing amplifying circuit and instrument calibration circuit three parts.Wherein directed mu balanced circuit is by diode D ₄, resistance R ₉With voltage stabilizing diode D ₃Series connection is connected and constitutes between power supply and the ground wire.This partial circuit principle of work is to utilize diode D ₄Unidirectional on state characteristic, guarantee the orientation works of electric current in the entire circuit, to prevent the power supply reversal connection; Pass through resistance R ₉After carrying out current limliting, utilize voltage stabilizing diode D again ₃Pressure stabilization function, for the circuit operate as normal provides a burning voltage.The sensing amplifying circuit is by triode T ₁Base terminal 12 and resistance R ₄After the series connection, 14 be connected with probe, popping one's head in 13 then is and resistance R again ₁With resistance R ₂Parallel connected end be connected resistance R ₁B end and resistance R ₂A end can pass through single-pole double-throw switch (SPDT) K ₁Selection is R ₁Or R ₂Enter this circuit working.K switch ₁Be connected potentiometer W ₁Adjustable end on, thereby couple together with reometer, reometer again by with resistance R ₈And resistance R ₇Series connection, final and triode T ₁Collector terminal 10 be connected this triode T ₁Emitter terminal 11 pass through resistance R ₆Be connected with power cathode and constitute.The principle of work of this partial circuit is to utilize the amplification characteristic of triode, makes the small variation of its resistance generation be amplified to 300-400 doubly owing to mixing other liquid test food; Owing to test foods such as milk, drinks, meats, its qualified product all has a resistance value of determining relatively at a certain temperature in the placement certain hour, so be to improve adjustment accuracy, is provided with the selection resistance R in addition ₁Or R ₂,, select resistance R according to the difference of tested object ₁Or resistance R ₂Enter circuit working.Wherein, resistance R ₁With the resistance of the food of required test, and resistance R ₄The summation of resistance, perhaps resistance R ₂With the resistance of the liquid food of required test, and resistance R ₄The summation of resistance all should be greater than 1M Ω, and the input impedance of guaranteeing this detector is high internal resistance.The instrument calibration circuit is by potentiometer W ₃Be connected resistance R ₉With voltage stabilizing diode D ₃Contact and resistance R ₇With resistance R ₈Contact between, be used for calibration current to express normal operating conditions, potentiometer W ₂Be connected resistance R ₉With voltage stabilizing diode D ₃Contact and potentiometer W ₁And between the contact of reometer, its adjustable end is to pass through resistance R ₅Be connected resistance R ₄With triode T ₁Base terminal 12 contact places, be used for the measuring limit value of calibration current table, potentiometer W ₁Two stiff ends and potentiometer W ₂Two stiff ends be in parallel, its adjustable end promptly is and K switch ₁Connect, be used for the null value of calibration current table.Voltage stabilizing diode D ₁Be to be connected in parallel on potentiometer W ₂Two stiff ends on, D ₂Be to be connected triode T ₁Base terminal 12 and power cathode between.

The utility model is owing to adopt triode T ₁Be main sensing amplification circuits, the resistance subtle change that food is mixed behind the liquid is amplified to 300-400 doubly, thereby makes the user can read required correct value accurately and rapidly; By the selection resistance R is set ₁Or R ₂, make circuit at different tested objects, select the resistance R of relative resistance ₁Or R ₂Enter in the circuit, thus and resistance R ₄The common resistance detecting circuit that constitutes the needed high internal resistance of the utility model makes the electric current in this circuit drop to microampere order (uA level), thereby has avoided probe to insert the electrolytic catalysis phenomenon that is produced in the test food, has improved measuring accuracy greatly; Again by potentiometer W ₁, W ₂And W ₃The instrument calibration circuit that is constituted carries out preoperative zeroing, transfers ultimate value and Control current table operate as normal reometer respectively, thereby has further improved the measuring accuracy of this tester.And of the present utility model simple in structure, volume is little, so it has simultaneously also possessed cost low, easy to carry advantage.

Description of drawings:

Fig. 1 is test circuit structure figure of the present utility model

Fig. 2 is an instrument case synoptic diagram of the present utility model

Embodiment:

This food liquid detector is made up of probe (probe 13 and probe 14), instrument case and testing circuit.Testing circuit is to be divided into directed mu balanced circuit, sensing amplifying circuit and instrument calibration circuit three parts.Wherein directed mu balanced circuit is by diode D ₄, resistance R ₉With voltage stabilizing diode D ₃Series connection is connected and constitutes between power supply and the ground wire.The sensing amplifying circuit is by triode T ₁Base terminal 12 and resistance R ₄After the series connection, be connected with probe 14 again.Pop one's head in and 13 then be and resistance R ₁With resistance R ₂Parallel connected end be connected resistance R ₁B end and resistance R ₂A end can pass through single-pole double-throw switch (SPDT) K ₁Select R ₁Or R ₂Enter this circuit working, wherein, resistance R ₁Resistance should be greater than resistance R ₂, because the internal resistance of liquid and solid is different, liquid is generally at 20K Ω-60K Ω, solid is then much bigger than the internal resistance of liquid, for reaching the requirement of high internal resistance, so the R of this detector ₁Adopt the resistance of 220K Ω, be used for detecting fixedly food; R ₂Then adopt the resistance of 470K Ω, be used for tracer liquid food.K switch ₁Be connected potentiometer W ₁Adjustable end on, thereby couple together with reometer, reometer again by with resistance R ₈And resistance R ₇Series connection, final and triode T ₁Collector terminal 10 be connected this triode T ₁Emitter terminal 11 pass through resistance R ₆Be connected with power cathode and constitute.T ₁Adopt the NPN transistor of high β value (300 times-400 times), low penetration electric current.The instrument calibration circuit is by potentiometer W ₃Be connected resistance R ₉With voltage stabilizing diode D ₃Contact and resistance R ₇With resistance R ₈Contact between.Potentiometer W ₂Be connected resistance R ₉With voltage stabilizing diode D ₃Contact and potentiometer W ₁And between the contact of reometer, its adjustable end is to pass through resistance R ₅Be connected resistance R ₄With triode T ₁Base terminal 12 contact places.Potentiometer W ₁Two stiff ends and potentiometer W ₂Two stiff ends be in parallel, its adjustable end promptly is and K switch ₁Connect.Voltage stabilizing diode D ₁Be to be connected in parallel on potentiometer W ₂Two stiff ends on, play and be potentiometer W ₁, W ₂A stable magnitude of voltage is set up at two ends, is the voltage drop value of PN junction, so just makes potentiometer W simultaneously ₂Adjustable end to triode T ₁Base stage a stable bias voltage is provided, thereby guarantee triode T ₁Can operate as normal.Voltage stabilizing diode D ₂Be to be connected triode T ₁Base terminal 12 and power cathode between, its effect is as potentiometer W ₂Provide stablize bias voltage after, at D ₂Pressure stabilization function under, make remaining on the certain value that zeroing voltage can be stable, promptly indicator points to null value.If at voltage stabilizing diode D ₂A two ends last inclined to one side road capacitor C in parallel again ₁, at potentiometer W ₃Two ends inclined to one side road capacitor C also in parallel ₂, at voltage stabilizing diode D ₃With a power filtering capacitor C in parallel between the ground wire ₃, these three electric capacity all play filter action, make the voltage of corresponding circuit part guarantee to press for galvanic current, and have strengthened the antijamming capability of circuit.

1, the calibration process of this detector

(1), because the power supply of this detector is the direct supply of selecting for use, and scope is at 4.5V-6V, and the working current of reometer is fixed, can operate as normal for guaranteeing reometer, then by regulator potentiometer W ₃Size calibrate potentiometer W ₃Calibration finish before dispatching from the factory by the producer;

(2), after reometer is in normal operating conditions, will pop one's head in 13 and the probe 14 between short circuit, at this moment, regulator potentiometer W ₁Adjustable end move up and down, the indicator calibration indication that makes reometer is on " zero graduation " position of reometer dial plate 15.Potentiometer W ₁Be mounted on the instrument case, the user can calibrate voluntarily on request;

(3), after reometer is in normal operating conditions, will pop one's head in 13 and the probe 14 between the open circuit, at this moment, regulator potentiometer W ₂Adjustable end move up and down, the indicator calibration indication that makes reometer is on " full scale " position of reometer dial plate 15.Potentiometer W ₂Be mounted on the instrument case, calibrate voluntarily by the user.

2, the operating process of this detector

After the said process calibration, and 16 light yellows of the pilot lamp on the instrument case, just can be used to accurate detection.(1), when detected object is foods such as beef, with the K switch on the instrument case ₁Pull the B place, (even resistance R ₁Enter circuit working), to pop one's head in again and 13 14 contact the food surface that to detect with probe, only with the concrete scale of the indication of the pointer on the scope dial plate 15, compare with the qualified resistance of this kind food more then, can learn the accurate content of other liquid in this food; (2), when detected object is liquid foods such as drinks, with the K switch on the instrument case ₁Pull the A place, (even resistance R ₂Enter circuit working), will pop one's head in again 13 and probe 14 insert in the liquid, through reading with relatively, can measure the accurate content of other impurity liquid.

Claims

1, a kind of food liquid detector is made up of probe, instrument case and testing circuit, it is characterized in that: testing circuit is to be divided into directed mu balanced circuit, sensing amplifying circuit and instrument calibration circuit three parts, and wherein directed mu balanced circuit is by diode D ₄, resistance R ₉With voltage stabilizing diode D ₃Series connection is connected and constitutes between power supply and the ground wire; The sensing amplifying circuit is by triode T ₁Base terminal (12) and resistance R ₄After the series connection, be connected with probe (14), pop one's head in (13) then are and resistance R again ₁With resistance R ₂Parallel connected end be connected resistance R ₁B end and resistance R ₂A end can pass through single-pole double-throw switch (SPDT) K ₁Selection is R ₁Or R ₂Enter this circuit working, K switch ₁Be connected potentiometer W ₁Adjustable end on, thereby couple together with reometer, reometer again by with resistance R ₈And resistance R ₇Series connection, final and triode T ₁Collector terminal (10) be connected this triode T ₁Emitter terminal (11) pass through resistance R ₆Be connected with power cathode and constitute; The instrument calibration circuit is by potentiometer W ₃Be connected resistance R ₉With voltage stabilizing diode D ₃Contact and resistance R ₇With resistance R ₈Contact between, potentiometer W ₂Be connected resistance R ₉With voltage stabilizing diode D ₃Contact and potentiometer W ₁And between the contact of reometer, its adjustable end is to pass through resistance R ₅Be connected resistance R ₄With triode T ₁Base terminal (12) contact place, potentiometer W ₁Two stiff ends and potentiometer W ₂Two stiff ends be in parallel, its adjustable end promptly is and K switch ₁Connect.

2, food liquid detector according to claim 1 is characterized in that: voltage stabilizing diode D ₁Be to be connected in parallel on potentiometer W ₂Two stiff ends on, D ₂Be to be connected triode T ₁Base terminal (12) and power cathode between.