CN106530909A - Beat frequency generating demonstrating instrument - Google Patents
Beat frequency generating demonstrating instrument Download PDFInfo
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- CN106530909A CN106530909A CN201710044889.7A CN201710044889A CN106530909A CN 106530909 A CN106530909 A CN 106530909A CN 201710044889 A CN201710044889 A CN 201710044889A CN 106530909 A CN106530909 A CN 106530909A
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B23/00—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes
- G09B23/06—Models for scientific, medical, or mathematical purposes, e.g. full-sized devices for demonstration purposes for physics
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- Apparatuses For Generation Of Mechanical Vibrations (AREA)
Abstract
The invention discloses a beat frequency generating demonstrating instrument, relating to the technical field of teaching demonstration appliances. The beat frequency generating demonstrating instrument comprises a power supply, oscillators, a power amplifier, loudspeakers and connectors, wherein the power supply adopts a 5V-12V direct-current power supply, the oscillators comprise a left oscillator (OL) and a right oscillator (OR), the loudspeakers comprise a left loudspeaker (SL) and a right loudspeaker (SR), the connectors comprise a left connector (BNCL) and a right connector (BNCR), the oscillators generate two groups of sinusoidal signals with small frequency difference values, the sinusoidal signals enter the power amplifier to be amplified, the amplified signals are respectively input into the loudspeakers, so that voice frequency is generated, and clear 'beat' sound is formed, the left connector and the right connector are connected with an external device, and the external device converts the 'beat' sound into oscillogram which is then output.
Description
Technical field
The present invention relates to teaching demonstration apparatus technical field, and in particular to a kind of beat frequency produces demonstrator.
Background technology
" beat frequency " (beat) phenomenon is an important physical phenomenon in higher education, in the academic neck such as optics, electromagnetism
Also there is important application (for example, measure, the musical instrument school of photo-beat method light-metering speed, sound wave or radio wave frequency in domain and daily life
Accurate, monitoring speed etc.).But the phenomena principles are very abstract, hard to understand.
In teaching process, in the case of invisible, impalpable, also indigestion claps phenomena principles to student.Before, once
To demonstrate bat phenomenon, (the close tuning forks of two frequencies of percussion are to produce sound wave, and then form bat now with tuning fork resonance teacher
As), but during this, being affected by the limitation of tuning fork itself, tone and loudness are difficult to control to, and operability is not strong, demonstration
DeGrain.
The content of the invention
The purpose of the present invention is for above-mentioned deficiency, it is proposed that one kind can vivid, intuitively demonstrate " beat frequency " phenomenon
Beat frequency produces demonstrator.
The present invention is specifically adopted the following technical scheme that：
A kind of beat frequency produces demonstrator, including power supply, oscillator, power amplifier, loudspeaker and jointing, oscillator
Including left side oscillator and right side oscillator, loudspeaker includes left speaker and right speaker, and connector includes that left side connects
Joint and right side connector, oscillator produce the little sinusoidal signal of two class frequency differences, and sinusoidal signal ingoing power amplifier enters
Row amplifies, and signal after amplification difference input loudspeaker produces audio frequency, and sound more clearly " is clapped " in formation, left side jointing and
Right side connector is connected with external equipment, and external equipment " will be clapped " sound and be converted into oscillogram output.
Preferably, the power supply is provided with battery main switch, and left speaker is provided with left speaker switch, and right side is raised
Sound device is provided with right speaker switch.
Preferably, the battery main switch, left speaker switch and right speaker switch are single knife switch.
Preferably, the left side oscillator and right side oscillator are RC bridge-type sine-wave oscillators.
Preferably, start beat frequency and produce demonstrator：
Closure battery main switch, left side oscillator, right side oscillator and power amplifier are powered, in running order；
Closure right speaker switch, disconnects left speaker switch, and right speaker sends and produced by right side oscillator
Respective frequencies be ω1Audio frequency；
Closure left speaker switch, disconnects right speaker switch, and left speaker sends and produced by left side oscillator
Respective frequencies be ω2Audio frequency；
Left speaker switch and right speaker switch are closed at, left speaker and right speaker are sent by a left side
The frequency that side oscillator and right side oscillator are produced is ω1And ω2The audio frequency of superposition, produces and claps phenomenon；
Left side connector, right side connector are connected into oscillographic X, Y passage respectively, is fitted, you can by oscillography
Phenomenon is clapped in device observation, so as to further simulating, analyzing.
Preferably, the power supply is 5V～12V dc sources.
The invention has the advantages that：Original sound source is substituted using circuit design, is analyzed to clapping phenomenon, is collected
In one, sound, electricity " will clap " that signal is vivid to be showed, integrate depending on, listen, blend learning in music；
Using RC bridge oscillator circuits, principle is simple, and components and parts are few, and small volume, output voltage are constant, and distortion is little, " bat "
Phenomenon is obvious；
This demonstrator small volume, it is low in energy consumption, and be difficult, by external environment influence, to can be widely applied in teaching demonstration；
Frequency is easily-controllable, workable, and design is simplified, it is easy to debug, and realizes beat frequency and send out while improving conventional efficient
Raw stability, accuracy；
This demonstrator can observation supporting with the instrument such as oscillograph, Multifunction video platform simulating the output wave of " bat " phenomenon
Abstract concept is converted into visual image by shape figure.
Description of the drawings
Fig. 1 produces demonstrator structure block diagram for the beat frequency；
Fig. 2 produces demonstrator circuit theory diagrams for the beat frequency；
Fig. 3 is RC bridge-type sine-wave oscillator circuit theory diagrams；
Fig. 4 is " displacement time " curve of two points of vibrations.
Wherein, 1 is power supply, and 2 is oscillator, and 3 is power amplifier, and 4 is oscillograph joint, and 5 is left side oscillator, and 6 are
Right side oscillator, 7 is left speaker, and 8 is right speaker, and 9 is left side connector, and 10 is right side connector.
Specific embodiment
The specific embodiment of the present invention is described further with specific embodiment below in conjunction with the accompanying drawings：
As shown in Figure 1-2, a kind of beat frequency produces demonstrator, including power supply 1, oscillator 2, power amplifier 3, loudspeaker and
Jointing, power supply 1 be 5V～12V dc sources, oscillator include left side 5 (O of oscillatorL) and 6 (O of right side oscillatorR), raise
Sound device includes 7 (S of left speakerL) and 8 (S of right speakerR), connector includes left side 9 (BNC of connectorL) and right side connection
10 (BNCR), oscillator produces the little sinusoidal signal of two class frequency differences, and sinusoidal signal ingoing power amplifier is amplified,
Signal difference input loudspeaker after amplification produces audio frequency, and sound more clearly " is clapped " in formation, and left side jointing and right side connect
Joint is connected with external equipment, and external equipment " will be clapped " sound and be converted into oscillogram output.
Power supply is provided with battery main switch (S1), left speaker is provided with left speaker switch (S3), right speaker
It is provided with right speaker switch (S2)。
Battery main switch, left speaker switch and right speaker switch are single knife switch.
Left side oscillator 5 and right side oscillator 6 are RC bridge-type sine-wave oscillators.
Start beat frequency and produce demonstrator：
Closure battery main switch, left side oscillator, right side oscillator and power amplifier are powered, in running order；
Closure right speaker switch, disconnects left speaker switch, and right speaker sends and produced by right side oscillator
Respective frequencies be ω1Audio frequency；
Closure left speaker switch, disconnects right speaker switch, and left speaker sends and produced by left side oscillator
Respective frequencies be ω2Audio frequency；
Left speaker switch and right speaker switch are closed at, left speaker and right speaker are sent by a left side
The frequency that side oscillator and right side oscillator are produced is ω1And ω2The audio frequency of superposition, produces and claps phenomenon；
Left side connector, right side connector are connected into oscillographic X, Y passage respectively, is fitted, you can by oscillography
Phenomenon is clapped in device observation, so as to further simulating, analyzing.
As shown in figure 3, RC bridge-type sine-wave oscillator circuit theory diagrams,
The Main Function of RC oscillating circuits is that vibration frequency is close, amplitude is equal, phase place identical simple harmonic quantity for generation two
Vibration, is that the synthesis for clapping phenomenon is laid the groundwork.The frequency of RC connection in series-parallel oscillators is easy to adjust, and adjustable range is also wider, and which is one
Plant positive feedback formula oscillator, R1、C1、R2、C2, the frequency selection circuit of composition, for easy analysis, takes R1=R2=R, C1=C2=C,
R1、C1Series impedance Z1=R1+1/jωC1,R2、C2Parallel impedance Z2=R2/ (1+j ω R2C2), the transmission system in the frequency-selective network
Number Fu：
Fu=UF/U0=Z2/(Z1+Z2)
=1/ [(1+R1/R2+C1/C2)+j(ωR1C2-1/ωR2C1)] (1)
Work as ω0=1/RC, ω=ω0When, can release transmission coefficient Fu by above formula with angle phi F occurrence is：
Fu=1/sqrt [(9-j (ω/ω0-ω0/ ω))]=1/3 (2)
φ F=-arctan [(ω/ω0-ω0/ ω)/3]=0 (3)
At this moment output frequency f is vibrated in RC connection in series-parallel0=1/2 π RC, by the value for changing R, C in RC backfeed loops, can obtain
To different frequency output signals.
RC series-parallel circuits maintain self-oscillation condition：
(1) amplitude conditions：AF=1 represents that feedback signal is equal in magnitude with input signal.
(2) phase condition：ψ=2n π (n is integer), represent feedback signal and input signal homophase.
When circuit starts starting of oscillation, pumping signal is very weak, and at this moment circuit needs positive feedback, i.e. AF>1, circuit could starting of oscillation.
After starting of oscillation, the amplitude of output signal slowly increases, when setting value is reached, it is necessary to AF=1, amplitude output signal is stablized
Get off.In main vibration circuit, if C1=C2=C, R1For constant, R2=R2X, changes output signal frequency, output frequency by adjusting Rx
Rate is：
f0=1/ [2 π C sqrt (R1R2x)] (4)
If RX>>R1, Fu=1/ (2+R can be obtained by (1) formula1/R2X) ≈ 1/2, by starting condition for oscillation | A*Fu |>1 A=1+ (RT+
RP)/R>2, i.e. circuit meet RT+RP>R, you can starting of oscillation.After starting of oscillation, output is when reaching setting value, allows RT+RPFixed ampllitude by=R, electricity
R in roadTTwo diode of a positive and a negative in parallel, according to volt-ampere of characteristic diode, subtracts with backfeed loop electric current increase resistance during starting of oscillation
Little, two diodes make the automatic starting of oscillation amplitude stubilization of circuit.
The Main Function of power amplifier is will to produce signal by RC oscillating circuits to be amplified, before clapping phenomenon generation
Carry.Due to RC oscillating circuits output signal be not enough to drive the speaker, so need to by its power amplification, with drive the speaker,
Realize clapping the synthesis and generation of phenomenon.
8002A is an audio frequency power amplifier with shutdown mode.8002A functional characteristics：
(1) without the need for output coupling capacitor or external buffer circuit.
(2) stable gain output.
(3) outside gain is arranged.
When working under 5V input voltages, it is 3W to load the mean power on (3 Ω), and the distortion factor is less than 5%.And it is right
For portable equipment, when VDD acts on shut-off end, 8002A will enter shutdown mode, and power consumption now is extremely low, IQOnly
For 0.6uA.8002A is the audio frequency power amplifier designed by the application scenario for aiming at high-power, high-fidelity.Required peripheral cell is few, and
Can work under the input voltage of 2.0V～5.5V.
Produce in demonstrator in this beat frequency,
R is set2、R3、R5、R6、R7For fixed value resistance；
R2=10K Ω, R3=15K Ω, R5=2.4K Ω, R6=10K Ω, R7=10K Ω；
R1、R4For variable resistor：R1=0～100K Ω, R4=0～100K Ω；
C1For variable condenser：C1=0.01～0.10uF；C2For fixed capacitor：C2=0.01uF.
The operation principle of left side oscillator and right side oscillator：
The circular frequency of two harmonic motions is respectively ω1And ω2, and ω1>ω2, for the sake of simplicity, make amplitude A1=A2=A,
Initial phase φ1=φ2=0.Then its vibration equation is respectively:
y1=Acos ω1t (5)
y2=Acos ω2t (6)
Closing vibration is
In above formulaIt is considered as closing the amplitude of vibration, it makees cyclically-varying with the time；And
BelowPart be then withFor the simple harmonic oscillation of circular frequency.
By analysis, clap phenomenon and there are following features：
(1) amplitude makees cyclically-varying with the time, and constant period, once strong and weak change turn to a bat.
(2) time (cycle clapped) of each bat be：
(3) closing the circular frequency vibrated is：
As shown in figure 4, a and b represent " displacement time " curve of two points of vibrations respectively, as seen from the figure, in t1Moment,
The phase place of two points of vibrations is identical；In t2Moment, the opposite in phase of two points of vibrations close amplitude minimum；In t3Moment, two points of vibrations
Phase place is again identical, and it is maximum again to close amplitude, in c, dotted line represent and the amplitude that vibrate to make periodicity with the time slowly varying, i.e.,
" bat " phenomenon.
Certainly, described above is not limitation of the present invention, and the present invention is also not limited to the example above, this technology neck
Change, remodeling, addition or replacement that the technical staff in domain is made in the essential scope of the present invention, should also belong to the present invention's
Protection domain.
Claims (6)
1. a kind of beat frequency produces demonstrator, it is characterised in that connect including power supply, oscillator, power amplifier, loudspeaker and connection
Head, oscillator include left side oscillator and right side oscillator, and loudspeaker includes left speaker and right speaker, connector bag
Left side connector and right side connector are included, oscillator produces the little sinusoidal signal of two class frequency differences, sinusoidal signal ingoing power
Amplifier is amplified, and the signal difference input loudspeaker after amplification produces audio frequency, and sound more clearly " is clapped " in formation, and left side connects
Joint and right side connector are connected with external equipment, and external equipment " will be clapped " sound and be converted into oscillogram output.
2. a kind of beat frequency as claimed in claim 1 produces demonstrator, it is characterised in that the power supply is provided with power supply and always opens
Close, left speaker is provided with left speaker switch, right speaker is provided with right speaker switch.
3. a kind of beat frequency as claimed in claim 2 produces demonstrator, it is characterised in that the battery main switch, left side are raised one's voice
Device is switched and right speaker switch is single knife switch.
4. a kind of beat frequency as claimed in claim 1 produces demonstrator, it is characterised in that the left side oscillator and right side vibration
Device is RC bridge-type sine-wave oscillators.
5. a kind of beat frequency as claimed in claim 1 produces demonstrator, it is characterised in that starts beat frequency and produces demonstrator：
Closure battery main switch, left side oscillator, right side oscillator and power amplifier are powered, in running order；
Closure right speaker switch, disconnect left speaker switch, right speaker send by right side oscillator produce it is right
Frequency is answered to be ω1Audio frequency；
Closure left speaker switch, disconnect right speaker switch, left speaker send by left side oscillator produce it is right
Frequency is answered to be ω2Audio frequency；
Left speaker switch and right speaker switch are closed at, left speaker and right speaker send and shaken by left side
The frequency for swinging device and the generation of right side oscillator is ω1And ω2The audio frequency of superposition, produces and claps phenomenon；
Left side connector, right side connector are connected into oscillographic X, Y passage respectively, is fitted, you can seen by oscillograph
Bat phenomenon is examined, so as to further simulating, analyzing.
6. a kind of beat frequency as claimed in claim 1 produces demonstrator, it is characterised in that the power supply is 5V～12V direct currents
Source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710044889.7A CN106530909A (en) | 2017-01-20 | 2017-01-20 | Beat frequency generating demonstrating instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710044889.7A CN106530909A (en) | 2017-01-20 | 2017-01-20 | Beat frequency generating demonstrating instrument |
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| Publication Number | Publication Date |
|---|---|
| CN106530909A true CN106530909A (en) | 2017-03-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710044889.7A Pending CN106530909A (en) | 2017-01-20 | 2017-01-20 | Beat frequency generating demonstrating instrument |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2804993Y (en) * | 2004-12-24 | 2006-08-09 | 南京师范大学 | Resonance caused by sound demonstration apparatus |
| RU103957U1 (en) * | 2010-12-24 | 2011-04-27 | Рагозин Сергей Владимирович | DEMONSTRATION SYSTEM FOR THE STUDY OF PHYSICAL PHENOMENA "UNIVERSAL" |
| CN105206145A (en) * | 2015-10-27 | 2015-12-30 | 新乡医学院 | Beat generator |
-
2017
- 2017-01-20 CN CN201710044889.7A patent/CN106530909A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2804993Y (en) * | 2004-12-24 | 2006-08-09 | 南京师范大学 | Resonance caused by sound demonstration apparatus |
| RU103957U1 (en) * | 2010-12-24 | 2011-04-27 | Рагозин Сергей Владимирович | DEMONSTRATION SYSTEM FOR THE STUDY OF PHYSICAL PHENOMENA "UNIVERSAL" |
| CN105206145A (en) * | 2015-10-27 | 2015-12-30 | 新乡医学院 | Beat generator |
Non-Patent Citations (2)
| Title |
|---|
| 冯容士 等: "《教学示波器》", 30 September 1979, 上海教育出版社 * |
| 张洪: ""拍"现象演示实验仪", 《大学物理实验》 * |
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Application publication date: 20170322 |