CN103646593A - Multifunctional teaching demonstration instrument with Schmitt trigger - Google Patents
Multifunctional teaching demonstration instrument with Schmitt trigger Download PDFInfo
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- CN103646593A CN103646593A CN201310732123.XA CN201310732123A CN103646593A CN 103646593 A CN103646593 A CN 103646593A CN 201310732123 A CN201310732123 A CN 201310732123A CN 103646593 A CN103646593 A CN 103646593A
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- circuit
- voltage
- schmitt trigger
- electromotive force
- resistance
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Abstract
A multifunctional teaching demonstration instrument with a Schmitt trigger comprises a resistance voltage division circuit, the Schmitt trigger and an automatic control terminal. The multifunctional teaching demonstration instrument is characterized in that the resistance voltage division circuit is parallelly connected with the Schmitt trigger and then connected with the automatic control terminal, resistance values of a thermistor, a photoresistor and an adjustable resistor in the resistance voltage division circuit are changed, different voltage is inputted to the automatic control terminal, and the principle of resistance voltage division, sensor element properties, NOT gate circuit properties, analog-digital signal conversion, automatic control and circuit sensitivity are demonstrated by the aid of a bell, a lamp and a buzzer. The multifunctional teaching demonstration instrument is reasonable in circuit design, simple in control and high in scientificity, students are helped by a specific experimental circuit to understand relevant textbook knowledge points, the process is lively and interesting, and learning enthusiasm of the students can be greatly stimulated.
Description
Technical field
The present invention relates to a kind of demonstration instrument for teaching, particularly a kind of this schmitt trigger multi-function teaching-aid display instrument.
Background technology
Si Mite Sheffer stroke gate claims again this schmitt trigger.This device both can be worked as common NOT-AND gate, also can form this schmitt trigger and use.In digital display circuit, will make pulse shaping circuit with it.The condition of work of this schmitt trigger circuit has threshold V T+and VT-, when input signal surpasses upper limit threshold VT+, circuit upset, when incoming level is got back to VT+, circuit does not turn back again, and must be when incoming level continues to drop to another threshold value VT-lower than VT+, circuit just can turn back original original state.
This schmitt trigger is important components and parts during high school physics is learned, in order to allow student in study, understand more intuitively the principle of this schmitt trigger, general teacher can make one or two relevant teaching aids according to actual conditions and demonstrate to everybody, but general single circuit demonstration effect is not clearly, and cost is higher, because make this schmitt trigger demonstration teaching aid with multiple demo function, for teaching of teacher, have great importance with student's understanding.
Summary of the invention
For the deficiency in existing this schmitt trigger demonstration teaching aid, the object of the present invention is to provide a kind of this schmitt trigger multi-function teaching-aid display instrument, by resistance in adjusting resistance bleeder circuit, to change the trigger rate of this schmitt trigger, make automatic control terminal pass through the direct read-out voltage value of digital display voltmeter, can reach the effect directly perceived of demonstrating principle, sensor element characteristic, the characteristic of not circuit, the conversion of modulus signal, robotization control and the circuit sensitivity of electric resistance partial pressure to student.
The present invention adopts following technical scheme: a kind of this schmitt trigger multi-function teaching-aid display instrument, comprise that resistor voltage divider circuit, this schmitt trigger and automatic control terminal form, and resistor voltage divider circuit is by an adjustable resistance R
2, photoresistance R
l, thermistor R
t, tongue tube R
bwith gauge tap k
0and k
1, k
2, k
3form, automatic control terminal is by digital display voltmeter, jingle bell, light fixture, hummer and gauge tap k
1, k
2, k
3form, it is characterized in that: described resistor voltage divider circuit connects with automatic control terminal with after this schmitt trigger parallel connection, change the resistance value of thermistor, photoresistance and adjustable resistance in resistor voltage divider circuit, to automatic control terminal, input different voltage and demonstrate out principle, sensor element characteristic, the not circuit characteristic of electric resistance partial pressure, the teaching aid of the conversion of modulus signal, robotization control, circuit sensitivity by jingle bell, light fixture, hummer.
The demonstration of described electric resistance partial pressure principle: closed k
0and k, that digital voltmeter 1 shows is the total voltage U of positive source, what digital voltmeter 2 showed is the voltage U of dividing point A
a, be also adjustable resistance R
2the voltage at two ends, is U if establish total voltage, and the expression formula that can be obtained A point electromotive force by proportionate relationship is
a=U
a=
u, R
1=R
2can make electromotive force that A is ordered just in time equal half of total voltage; Reduce R
1or increase R
2,can make the electromotive force of A raise, verify " in series circuit, voltage is directly proportional to resistance " principle.
Described sensor element characteristic demonstrating: closed k
1and k, be equivalent to use photosensitive resistance R
lsubstituted the R demonstrating in 1
2, now A point electromotive force only has photoresistance R completely
lvalue decide, to photoresistance R
lblock, the registration that can find digital voltmeter 2, changing, is blocked manyly, and the registration of digital voltmeter 2 is just larger, illustrates that the electromotive force that now A order is at increase, R
lresistance reducing and increase with intensity of illumination; Closed k
2and k, be equivalent to use thermistor R
tsubstituted the R demonstrating in 1
2, R
1can be set as constantly, now A point electromotive force only has thermistor R completely
tvalue decide, with lighter flame to thermistor R
ttoast, can find that the registration of digital voltmeter 2 is changing, the time of baking is longer, R
ttemperature higher, the registration of digital voltmeter 2 is just larger, the electromotive force that now A order is at increase R
tresistance with the rising of temperature, increase; Closed k
3and k, be equivalent to use tongue tube R
bsubstituted the R demonstrating in 1
2, this tongue tube is closed type, therefore while not adding magnetic field, A point is by this switch ground connection, electromotive force is zero, Y point high potential, when have magnetic field near time, switch opens, the rising of A point electromotive force, the reduction of Y point electromotive force, verificating sensor element characteristic.
Described not circuit characteristic demonstrating is the input end that the output voltage of adjusting resistance bleeder circuit is received the not circuit of this schmitt trigger: input one higher than 3.2V high voltage, not circuit output terminal obtains a 0.0V low-voltage; Input a low-voltage lower than 2.4V, not circuit output terminal obtains a 6.0V high voltage, demonstrates the contrary characteristic of not circuit input and output terminal voltage height.
The conversion demonstration of described modulus signal, that modulus signal only has two states, i.e. " height " and " low ", by numeral, embody and be expressed as " 1 " and " 0 ", the voltage of not circuit input end is adjustable continuously, a high voltage 6.0V, one is low-voltage 0V, represents high " 1 " and represents low " 0 " these two digitized electric signal.
Described automated control technology demonstration: be closed different k, k
1, k
2and k
3, make LED lamp, alarm and speaker operation, realize and automatically control demonstration.
The invention has the beneficial effects as follows: this circuit design is reasonable, control simply, by concrete experimental circuit, help student to carry out the understanding of textbook correlated knowledge point, by force scientific, process vivid and interesting, can excite student's learning enthusiasm greatly.
Accompanying drawing explanation
Fig. 1 is these schmitt trigger multi-function teaching-aid display instrument circuit theory diagrams of the present invention.
Embodiment
Below in conjunction with drawings and Examples, the invention will be further described.
By Fig. 1, known, a kind of this schmitt trigger multi-function teaching-aid display instrument, comprises that resistor voltage divider circuit, this schmitt trigger and automatic control terminal form, and resistor voltage divider circuit is by an adjustable resistance R
2, photoresistance R
l, thermistor R
t, tongue tube R
bwith gauge tap k
0and k
1, k
2, k
3form, automatic control terminal is by digital display voltmeter, jingle bell, light fixture, hummer and gauge tap k
1, k
2, k
3form, described resistor voltage divider circuit connects with automatic control terminal with after this schmitt trigger parallel connection, change the resistance value of thermistor, photoresistance and adjustable resistance in resistor voltage divider circuit, to automatic control terminal, input different voltage and demonstrate out principle, sensor element characteristic, the not circuit characteristic of electric resistance partial pressure, the teaching aid of the conversion of modulus signal, robotization control, circuit sensitivity by jingle bell, light fixture, hummer.
Embodiment 1:
The demonstration of electric resistance partial pressure principle: first restore (all switches all cut out, below " first restoring " be this meaning), closed k
0and k, what now can see that digital voltmeter 1 shows is that the new battery of total voltage U(of positive source is about 6.0V, after use, can slightly decline), what digital voltmeter 2 showed is the voltage U of dividing point A
a, also get final product resistance R
2the voltage at two ends, is U if establish total voltage, and the expression formula that can be obtained A point electromotive force by proportionate relationship is
a=U
a=
u, now can be to student question: how (1) sets R
1, R
2resistance, can make electromotive force that A is ordered just in time equal half of total voltage? answer: as long as R
1=R
2, numerical value is appointed and is got.(2) how to regulate R
1, R
2resistance can make the electromotive force of A raise? answer: reduce R
1or increase R
2.
Embodiment 2:
Sensor element characteristic demonstrating: closed k
1and k, be equivalent to use photosensitive resistance R
lsubstituted the R demonstrating in 1
2, R
1can be set as 5K Ω, now A point electromotive force only has photoresistance R completely
lvalue decide, with hand to photoresistance R
lblock, the registration that can find digital voltmeter 2, changing, is blocked manyly, and the registration of digital voltmeter 2 is just larger, illustrates that the electromotive force that now A order is that reason is photoresistance R in increase
lresistance increasing, now can be to student question: this photoresistance R
lthere is there what characteristic? answer: R
lresistance reducing and increase with intensity of illumination.Then do demonstration in the other direction; (2) first restore closed k
2and k, be equivalent to use thermistor R
tsubstituted the R demonstrating in 1
2, R
1can be set as 1K Ω constant, now A point electromotive force only has thermistor R completely
tvalue decide, with lighter flame to thermistor R
ttoast, can find that the registration of digital voltmeter 2 is changing, the time of baking is longer, R
ttemperature higher, the registration of digital voltmeter 2 is just larger, illustrates that the electromotive force that now A order is that reason is thermistor R in increase
tresistance increasing, now can be to student question: this thermistor R
tthere is there what characteristic? answer: R
tresistance with the rising of temperature, increase.Remake demonstration in the other direction.(3) first restore closed k
3and k, be equivalent to use tongue tube R
bsubstituted the R demonstrating in 1
2, this tongue tube is closed type, therefore while not adding magnetic field, A point is by this switch ground connection, electromotive force is zero, Y point high potential, when have magnetic field near time, switch opens, the rising of A point electromotive force, the reduction of Y point electromotive force.
Embodiment 3:
The demonstration of not circuit characteristic: not gate is a kind of basic digital logic gates, it has two ports of input and output, not circuit is characterised in that the electromotive force height of output terminal is just in time contrary with the height of input end electromotive force, be that input end adds a high voltage (logical symbol is 1), output terminal just there will be low-voltage (logical symbol is 0), otherwise input end adds a low-voltage (logical symbol is 0), output terminal just there will be high voltage (logical symbol is 1).6 identical not circuits are contained altogether in this 74LS14 integration module inside, and this experiment is used one of them to demonstrate, and input/output terminal is denoted as respectively X and Y.During demonstration, first restore closed k
0and K, by R
1resistance be set as 1k Ω, by R
2resistance be made as 0 Ω, the existing R that increases gradually
2value, the registration of voltage table 2 can increase gradually obviously, the now synchronous variation of noting observing voltage table 3 registrations, find when X input terminal voltage is lower (lower than 3.0V), what output terminal Y exported always is a high voltage (6.0V), when X input terminal voltage is higher (higher than 3.0V), what output terminal Y exported always is a low-voltage (0.0V), has embodied the characteristic of not circuit.Remake demonstration in the other direction.
Specific embodiment 4:
The demonstration of modulus signal feature: the voltage of X input end is continuous variable, this is the feature of simulating signal, and the signal of Y output terminal is great-jump-forward variation, suddenlys change in other words conj.or perhaps, only has two values, and non-height is low, and this is the feature of digital signal.Analog signal transmission is unstable, is easily disturbed, and progressively eliminates; And digital signal is stable, be difficult for being disturbed, just doing comprehensive popularization.
Embodiment 5:
Automated control technology demonstration: (1) simulation automatic switch street lamp, first restores closed k, k
1and k
2, by R
1be set as 5k Ω, now photoresistance is under normal office illumination condition, resistance is less, the electromotive force that A is ordered is lower, for schmitt trigger, due to the input of X end is low-voltage, the output of Y end is high voltage, between BY, there is no electric potential difference, LED lamp can not be worked, when living photoresistance with stick shift, its resistance rises rapidly, make the electromotive force that A is ordered increase, when rising to the trigger voltage of not circuit, electromotive force (is about 2.4V), the electromotive force of Y end can overturn, by high potential bust, it is low potential (being about 1.2V), the two ends of LED lamp will form an electric potential difference like this, LED lamp is lit, when handle is taken away, photoresistance recovers illumination, its resistance can decline suddenly, cause the electromotive force that A is ordered to reduce, when trigger voltage lower than not circuit (being about 1.8V), the electromotive force of Y end can overturn, and by low potential, is jumped as high potential (being about 6.0V), the two ends electromotive force of LED lamp equates like this, LED lamp automatic distinguishing.(2) simulated fire warning circuit, first restores closed k
2and k, by R
1be set as 1k Ω, now thermistor is under normal temperature condition, resistance is less, the electromotive force that A is ordered is lower, for schmitt trigger, due to the input of X end is low-voltage, the output of Y end is high voltage, between BY, there is no electric potential difference, alarm can not be worked, when thermistor being heated with lighter, its resistance rises rapidly, make the electromotive force that A is ordered increase, when rising to the trigger voltage of not circuit, electromotive force (is about 2.4V), the electromotive force of Y end can overturn, by high potential bust, it is low potential (being about 1.2V), the two ends of alarm will form an electric potential difference like this, alarm luminous and sounding type starts to report to the police, when lighter is taken away, thermistor temp declines, its resistance declines immediately, cause the electromotive force that A is ordered to reduce, when trigger voltage lower than not circuit (being about 1.8V), the electromotive force of Y end can overturn, and by low potential, is jumped as high potential (being about 6.0V), now the electromotive force at alarm two ends equates, alarm stop alarm.(3) first restore closed k
3and k, by R
1be set as 5k Ω, by magnet, near tongue tube, loudspeaker meeting sounding, takes away magnet, and loudspeaker stops sounding.
Embodiment 6:
Control sensitivity adjustment demonstration: different users is different to the requirement of the condition of work of trigger, now R
1resistance just can play trigger sensitivity and regulate the effect of controlling.To automatic street lamp control system, reduce R
1, can improve sensitivity, when illuminance not enough hour, street lamp just can be lit; Otherwise, increase R
1, with regard to desensitization, must be when illuminance be very little, street lamp just can be lit.In like manner, thermosensitive circuit also possesses this function.
Claims (6)
1. this schmitt trigger multi-function teaching-aid display instrument, comprises that resistor voltage divider circuit, this schmitt trigger and automatic control terminal form, and resistor voltage divider circuit is by an adjustable resistance R
2, photoresistance R
l, thermistor R
t, tongue tube R
bwith gauge tap k
0and k
1, k
2, k
3form, automatic control terminal is by digital display voltmeter, jingle bell, light fixture, hummer and gauge tap k
1, k
2, k
3form, it is characterized in that: described resistor voltage divider circuit connects with automatic control terminal with after this schmitt trigger parallel connection, change the resistance value of thermistor, photoresistance and adjustable resistance in resistor voltage divider circuit, to automatic control terminal, input different voltage and demonstrate out principle, sensor element characteristic, the not circuit characteristic of electric resistance partial pressure, the teaching aid of the conversion of modulus signal, robotization control, circuit sensitivity by jingle bell, light fixture, hummer.
2. this schmitt trigger multi-function teaching-aid display instrument according to claim 1, is characterized in that: the demonstration of described electric resistance partial pressure principle: closed k
0and k, that digital voltmeter 1 shows is the total voltage U of positive source, what digital voltmeter 2 showed is the voltage U of dividing point A
a, be also adjustable resistance R
2the voltage at two ends, is U if establish total voltage, and the expression formula that can be obtained A point electromotive force by proportionate relationship is
a=U
a=
u, R
1=R
2can make electromotive force that A is ordered just in time equal half of total voltage; Reduce R
1or increase R
2,can make the electromotive force of A raise, verify " in series circuit, voltage is directly proportional to resistance " principle.
3. this schmitt trigger multi-function teaching-aid display instrument according to claim 1, is characterized in that: described sensor element characteristic demonstrating: closed k
1and k, be equivalent to use photosensitive resistance R
lsubstituted the R demonstrating in 1
2, now A point electromotive force only has photoresistance R completely
lvalue decide, to photoresistance R
lblock, the registration that can find digital voltmeter 2, changing, is blocked manyly, and the registration of digital voltmeter 2 is just larger, illustrates that the electromotive force that now A order is at increase, R
lresistance reducing and increase with intensity of illumination; Closed k
2and k, be equivalent to use thermistor R
tsubstituted the R demonstrating in 1
2, R
1can be set as constantly, now A point electromotive force only has thermistor R completely
tvalue decide, with lighter flame to thermistor R
ttoast, can find that the registration of digital voltmeter 2 is changing, the time of baking is longer, R
ttemperature higher, the registration of digital voltmeter 2 is just larger, the electromotive force that now A order is at increase R
tresistance with the rising of temperature, increase; Closed k
3and k, be equivalent to use tongue tube R
bsubstituted the R demonstrating in 1
2, this tongue tube is closed type, therefore while not adding magnetic field, A point is by this switch ground connection, electromotive force is zero, Y point high potential, when have magnetic field near time, switch opens, the rising of A point electromotive force, the reduction of Y point electromotive force, verificating sensor element characteristic.
4. this schmitt trigger multi-function teaching-aid display instrument according to claim 1, it is characterized in that: described not circuit characteristic demonstrating, the input end that the output voltage of adjusting resistance bleeder circuit is received the not circuit of this schmitt trigger: input one higher than 3.2V high voltage, not circuit output terminal obtains a 0.0V low-voltage; Input a low-voltage lower than 2.4V, not circuit output terminal obtains a 6.0V high voltage, demonstrates the contrary characteristic of not circuit input and output terminal voltage height.
5. this schmitt trigger multi-function teaching-aid display instrument according to claim 1, it is characterized in that: the conversion demonstration of described modulus signal, that modulus signal only has two states, i.e. " height " and " low ", by numeral, embody and be expressed as " 1 " and " 0 ", the voltage of not circuit input end is adjustable continuously, a high voltage 6.0V, one is low-voltage 0V, represents high " 1 " and represents low " 0 " these two digitized electric signal.
6. this schmitt trigger multi-function teaching-aid display instrument according to claim 1, is characterized in that: described automated control technology demonstration: be closed different k ', k, k
1, k
2and k
3, make LED lamp, alarm and speaker operation, realize and automatically control demonstration.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310732123.XA CN103646593A (en) | 2013-12-27 | 2013-12-27 | Multifunctional teaching demonstration instrument with Schmitt trigger |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310732123.XA CN103646593A (en) | 2013-12-27 | 2013-12-27 | Multifunctional teaching demonstration instrument with Schmitt trigger |
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| CN103646593A true CN103646593A (en) | 2014-03-19 |
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Application publication date: 20140319 |