CN107834999B - Single pulse and continuous pulse generator based on Schmitt trigger - Google Patents
Single pulse and continuous pulse generator based on Schmitt trigger Download PDFInfo
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- CN107834999B CN107834999B CN201711412563.1A CN201711412563A CN107834999B CN 107834999 B CN107834999 B CN 107834999B CN 201711412563 A CN201711412563 A CN 201711412563A CN 107834999 B CN107834999 B CN 107834999B
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- 239000003990 capacitor Substances 0.000 claims abstract description 21
- 238000007493 shaping process Methods 0.000 claims abstract description 18
- 230000010355 oscillation Effects 0.000 abstract description 8
- 238000010586 diagram Methods 0.000 description 6
- 238000013461 design Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000000630 rising effect Effects 0.000 description 4
- 238000007599 discharging Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
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- 238000005516 engineering process Methods 0.000 description 1
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- 238000005259 measurement Methods 0.000 description 1
- 208000001491 myopia Diseases 0.000 description 1
- 230000004379 myopia Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
- H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
- H03K3/027—Generators characterised by the type of circuit or by the means used for producing pulses by the use of logic circuits, with internal or external positive feedback
- H03K3/037—Bistable circuits
- H03K3/0377—Bistables with hysteresis, e.g. Schmitt trigger
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
- H03K3/64—Generators producing trains of pulses, i.e. finite sequences of pulses
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- Manipulation Of Pulses (AREA)
- Electrotherapy Devices (AREA)
Abstract
The invention discloses a single pulse and continuous pulse generator based on a Schmitt trigger, which comprises an anti-noise resistance-capacitance network circuit, a pulse shaper circuit, an oscillator circuit, a gating voltage generation circuit and an output shaping circuit formed by two Schmitt triggers. The noise-resistant resistance-capacitance network circuit consists of a resistor R 2 Capacitor C 1 The noise-resistant resistance-capacitance network is formed, so that possible interference can be eliminated. The pulse shaper circuit consists of a Schmitt trigger N 1 Resistance R 2 、R 1 Capacitance C 1 If the switch S is touched 1 Is pressed to pop up immediately, schmitt trigger N 1 A regular single pulse is output. The oscillator circuit, the schmitt trigger N 2 Oscillation capacitor C 3 Resistance R 5 Potentiometer P 2 Forming a multivibrator circuit. The gate voltage generation circuit, if the switch S is continuously turned on 1 ，N 1 The output keeps high level continuously, and N is supplied 2 As the gating voltage of the oscillator. The pulse output shaping circuit is composed of a trigger circuit N 3 、N 4 The composition is formed.
Description
Technical Field
The invention relates to a pulse generator technology, in particular to a generator capable of selectively generating single pulse or continuous pulse, which is based on a Schmitt trigger, so that small signal interference can be well avoided.
Background
The voltage or current with extremely short action time is called a pulse signal and can be periodically repeated or aperiodic or single-time. Pulse signals are widely used in the fields of computers, electrical equipment, measurement, control and the like, for example, in synchronous timing circuits, clock pulses control and coordinate the operation of the whole system, so that the characteristics of the clock pulses directly relate to whether the system can work normally or not and how.
The pulse signal generator is a generator capable of generating rectangular pulses with adjustable width, amplitude and repetition frequency, and two general approaches for obtaining rectangular pulse waveforms are adopted: 1) Directly generating a required rectangular pulse by using a multivibrator circuit, such as a multivibrator consisting of an NE555 timer; 2) The existing periodically varying waveforms are transformed by a shaping circuit into rectangular pulses meeting the requirements, but the latter is premised on the possibility of finding an existing voltage signal that meets both the requirements of frequency and amplitude.
The multivibrator formed by the NE555 timer can only output one continuous rectangular wave pulse, and is difficult to form a single pulse; the D-type flip-flop may form a single pulse flip-flop. Some industrial equipment, such as stepper motors, require flexible control of the working process, either in a single step or in a continuous process.
Designing a circuit with two working modes, if we press the button switch(s) only, then only one 'clean and single' pulse appears at the output end of the circuit, and the pulse can be positive pulse or negative pulse; if we short the switch, then several pulses will be generated at the output and the number of pulses will last until the switch is released.
Disclosure of Invention
The invention aims to provide equipment which has simple structure, low cost, reliable use and capability of selectively generating single pulse and continuous pulse generators.
In order to achieve the above object, the present invention provides a single pulse and continuous pulse generator based on schmitt trigger, which comprises an anti-noise rc network circuit, a pulse shaper circuit, an oscillator circuit, a gating voltage generating circuit, and an output shaping circuit composed of two schmitt triggers; switch S 1 The signal generated enters the pulse shaper circuit through the anti-noise resistive-capacitive network circuit if the switch button S is touched 1 Pulse shaper circuit N 1 Outputting a regular single pulse, directly entering an output shaping circuit formed by connecting two Schmitt triggers N3 and N4, and finally outputting a single pulse; if the switch button S is continuously pressed 1 Pulse shaper circuit N 1 The output is kept at a high level continuously, and is supplied to an oscillator circuit N2 as a gate voltage of the oscillator, and the oscillator circuit outputs continuous pulses through an output shaping circuit composed of two Schmitt triggers.
The noise-resistant resistance-capacitance network circuit consists of a resistor R 2 Connection capacitor C 1 The noise-resistant resistance-capacitance network is formed, so that possible interference can be eliminated.
The pulse shaper circuit consists of a Schmitt trigger N 1 Resistance R 2 、R 1 Capacitance C 1 If the switch S is touched 1 Is pressed to pop up immediately, schmitt trigger N 1 A regular single pulse is output.
The oscillator circuit is composed of a Schmitt trigger N 2 The input end 2 pin of (2) is connected with an oscillating capacitor C 3 The 3 pins of the output resistor N2 are sequentially connected with a potentiometer P 2 Resistance R 5 、N 2 Is connected to the input terminal 2 of the circuit to form a multivibrator circuit.
The gate voltage generation circuit, if the switch S is continuously turned on 1 ，N 1 The output continuously keeps a high level, the high level is connected with the 1 end of the oscillating circuit N2 through the resistor R4, the potentiometer P1 and the capacitor C2 in sequence, and the level is taken as the oscillating circuit N 2 Is set to the gate voltage of (a).
The output shaping circuit and the trigger N 3 Output negative pulse signal N 4 And outputting a positive pulse signal.
Drawings
Fig. 1, 2 and 3 are provided to provide a further understanding of the present invention, and fig. 1 is an electrical schematic diagram of a single and continuous pulse generator designed based on a schmitt trigger in accordance with the present invention, forming a part of the present application. Fig. 2 is a waveform diagram of a single pulse forming circuit test point. Fig. 3 is a waveform diagram of a continuous pulse generator test point.
Detailed Description
Fig. 1 is an electrical schematic diagram of a single and continuous pulse generator based on schmitt trigger designed according to the present invention, which includes an anti-noise rc network circuit, a pulse shaper circuit, an oscillator circuit, a gate voltage generating circuit, and an output shaping circuit composed of two schmitt triggers, and the present invention is described in detail below.
Since the design mainly uses the output characteristics specific to the schmitt trigger, it is necessary to understand the characteristics of the trigger.
Output characteristics of schmitt trigger circuit: schmitt trigger is a circuit often used in pulse waveform conversion and has two important characteristics in performance.
One is an input level corresponding to a transition of a circuit state during a rise of an input signal from a low level, and is different from an input transition level corresponding to a fall of the input signal from a high level.
And secondly, the edges of the output voltage waveform become very steep through a positive feedback process inside the circuit when the circuit state is switched. By utilizing the two characteristics, the signal waveform with slow edge change can be shaped into rectangular waves with steep edges, and noise superposed on the high and low levels of rectangular pulses can be effectively eliminated.
The "shaping" nature of conventional schmitt triggers shapes an irregular input signal into a standard pulse signal output.
Single pulse and multiple pulse electrical principle is generated by using a schmitt trigger: the electric schematic diagram for generating single pulse and continuous pulse by adopting Schmitt trigger is shown in figure 1, and comprises five modules of an anti-noise resistance-capacitance network circuit, a pulse shaper circuit, an oscillator circuit, a gating voltage generating circuit and an output shaping circuit formed by two Schmitt triggers.
Wherein IC 1 The integrated circuit is model 74LS132 and is formed of 4 Schmitt triggers, each having a 2-input NAND gate, which flip-flop toggles at different points when either a positive polarity (rising edge) or negative polarity (falling edge) signal is input. The difference between the positive and negative polarity voltages is determined by the hysteresis voltage. N in the circuit diagram 1 、N 2 、N 3 、N 4 Each belonging to one of the triggers is not described in detail below.
Switch anti-jitter and single pulse forming circuit: capacitor C at the moment of switching on the power supply of the circuit 1 The voltage cannot be suddenly changed, corresponding to short circuit, N 1 Input U N1-8 (8 or 9 feet) is 0, and the output end (10 feet) U N1-10 At high level, capacitor C 1 Through resistance R 2 Slowly charge when the input voltage exceeds the rising edge threshold U + When N 1 The output is inverted to a 0 level, and the initialization process of the circuit ends. As shown in fig. 2.
When the switch S is touched 1 When pressed, capacitor C 1 By R 1 (470 Ω) is greater than the supply through resistor R 2 (470 kΩ) to capacitor C 1 Charging current of charging, so C 1 The voltage at the two ends gradually decreases, when U C1 <U — (Schmitt trigger N) 1 Falling edge threshold voltage of (v), N 1 The output voltage is inverted to a high level "1", if the switch S is continuously turned on 1 ，N 1 The output keeps high level continuously, and N is supplied 2 Gating as an oscillatorA voltage; as shown in fig. 2.
If the switch S is touched 1 Immediately spring up, capacitor C 1 Continue to be powered through R 2 Slowly charge, when U C1 >U + (Schmitt trigger N) 1 Threshold voltage of rising) of the voltage sensor, N 1 The output is immediately inverted to a low level "0" to the schmitt trigger N 1 Outputting a regular pulse, as shown in FIG. 2, which pulse is to be triggered by the Schmitt trigger N 3 、N 4 The final output signal (single pulse) of the circuit is formed by further shaping, and can be positive pulse (A end) or negative pulse (B end).
From the resistance R 2 Capacitor C 1 The noise-resistant resistance-capacitance network is formed, so that possible interference such as switching noise or switching jitter can be eliminated.
Multivibrator circuit consisting of a schmitt trigger: schmitt trigger N 2 Oscillation capacitor C 3 Resistance R 5 Potentiometer P 2 Forms a multivibrator circuit, R 5 、P 2 Constitute schmitt trigger N 2 Is a hysteresis resistor which determines the schmitt trigger N 2 I.e. two threshold voltages (rising edge U + Falling edge U -- ) As shown in fig. 3.
Capacitor C at the moment of power on 3 Corresponding to short-circuiting, i.e. N 2 Input (1 foot) U N2-1 =0, at this time N 2 Output end (3 feet) U N2-3 At high level, U N2-3 Through resistor R 5 Potentiometer P 2 Give electric capacity C 3 Charging, as shown in U of FIG. 3 N2-1 The method comprises the steps of carrying out a first treatment on the surface of the When the capacitor C 3 The voltage on rises to N 2 When the threshold voltage is raised, the trigger is turned over, N 2 Output U N2-3 Jump to low level, at this time, capacitor C 3 And pass through resistor R 5 Potentiometer P 2 Discharging when the capacitor C 3 When the voltage on the circuit drops to the threshold voltage of the falling edge, the circuit is turned over again, U N2-3 And jump to low level, so that a continuous square pulse is outputAnd (5) punching. U as shown in figure 3 N2-3 。
Strictly speaking, N at this time 2 Outputting square wave pulses which are not standard, and finally passing through N 3 、N 4 The shaping circuit forms a standard square wave. Changing resistance R 5 Potentiometer P 2 Resistance or change capacitance C 3 The design is based on P 2 The oscillation frequency is adjusted.
The schmitt trigger with only one input end can oscillate continuously after being connected with the power supply when the multivibrator is formed, and the power supply must be cut off in order to stop oscillating. 74LS132 is a Schmitt trigger having two inputs, with the addition of a gating input, which can be used to conveniently control the oscillation or stop of the multivibrator. When the gating control end is low level 0, the output will keep high level unchanged, and the multivibrator cannot start vibrating; the multivibrator can generate oscillation only when the gating input terminal is in a high level 1, so that the multivibrator is flexible to be applied to practical circuits. N (N) 2 The other input terminal (2 pins) of the multi-resonant circuit is the gating input terminal, N 2 The voltage at the input end (2 pins) of (C) is represented by a capacitor 2 Is determined by the charging voltage of U of FIG. 3 N2-2 。
Generation of a gating voltage: if the button S is touched 1 The pressing time is longer, then from S 1 Press-to-multiple harmonic oscillation circuit N 2 Will have a delay time in operation, which is defined by resistor R 4 Potentiometer P 1 Capacitance C 2 The time constant of the formed RC network determines the delay time, so the potentiometer P 1 The delay time may be adjusted.
Capacitor C 2 Then pass through resistor R during this time 4 Potentiometer P 1 Charge to high level voltage, capacitor C 2 High level voltage at two ends as multi-harmonic oscillating circuit N 2 The oscillator starts to oscillate.
Up to this point, this gate N 2 The generation of a multi-pulse signal is started, and then the multi-pulse signal is passed through a shaping circuit N 3 、N 4 Shaping to formStandard pulse signal, output from output terminal, N 3 Output a negative pulse signal, such as U of FIG. 3 B ；N 4 Output positive pulse signal, such as U of FIG. 3 A Until the tact button pops up.
N 3 And D 1 Is used to ensure C 2 Rapidly discharging to avoid that we press or release the tact button S if it is repeatedly pressed or released 1 When the oscillator is started, the oscillator is prevented from vibrating.
Simulation software tests find that if P 1 Is adjusted too small, then C 2 May be charged to another value, easily causing false oscillations; p pair P 2 And C 3 As well as the oscillator N 2 The oscillation frequency of (2) can be determined from myopia as follows:
f=
wherein the frequency f is in hertz, the resistance is in ohms, and the capacitance is in Farad.
The actual frequency also depends on the integrated circuit IC used 1 Which may vary from manufacturer to manufacturer.
The total power consumption of the circuit is only a few milliamperes.
The pulse generator circuit has simple structure, ingenious thought and quite low manufacturing cost, and the microcomputer system can produce the same effect, but the microcomputer system has high manufacturing cost and complex design, and the design has better stability than the related products controlled by a computer, so that special applications in industrial control are well solved.
Claims (4)
1. The single pulse and continuous pulse generator based on the Schmitt trigger is characterized by comprising an anti-noise resistance-capacitance network circuit, a pulse shaper circuit, an oscillator circuit, a gating voltage generation circuit and an output shaping circuit formed by two Schmitt triggers; the noise-resistant resistance-capacitance network circuit consists of a resistor R 2 Connection capacitor C 1 Forming an anti-noise RC network for eliminating possible interference, said pulse shaper circuit consisting of a Schmitt trigger N 1 The two input ends are connected in short circuit, and the input end is connected with a resistor R 2 、R 1 Capacitance C 1 Constitution, resistance R 2 The other end is connected with a 5V power supply and a resistor R 1 The other end is connected with the tact switch S in turn 1 Capacitance C of working area 1 The other end is connected with a working place, a switch S 1 The signal generated enters the pulse shaper circuit through the anti-noise resistive-capacitive network circuit if the switch button S is touched 1 Pulse shaper circuit N 1 Outputting a regular single pulse, directly entering the circuit formed by two Schmitt triggers N 3 Connection N 4 The output shaping circuit is formed and outputs a single pulse finally; if the switch button S is continuously pressed 1 Pulse shaper circuit N 1 The output keeps high level continuously and is supplied to the oscillator circuit N 2 As a gate voltage of the oscillator, the oscillator circuit outputs a continuous pulse through an output shaping circuit constituted by two schmitt triggers.
2. The single and continuous pulse generator based on a schmitt trigger according to claim 1, characterized in that: the oscillator circuit is composed of a Schmitt trigger N 2 The input end 2 pin of (2) is connected with an oscillating capacitor C 3 ，N 2 The output resistor 3 pins of (2) are connected with the potentiometer P in turn 2 Resistance R 5 、N 2 Is connected to the input terminal 2 of the circuit to form a multivibrator circuit.
3. The single and continuous pulse generator based on a schmitt trigger according to claim 1, characterized in that: the gate voltage generation circuit, if the switch S is continuously turned on 1 ，N 1 The output continues to hold a high level which in turn passes through resistor R 4 Potentiometer P 1 Capacitance C 2 Connected with an oscillating circuit N 2 At 1 end of (1), this level is used as an oscillating circuit N 2 Is set to the gate voltage of (a).
4. The single and continuous pulse generator based on a schmitt trigger according to claim 1, characterized in that: the output shaping circuit and the trigger N 3 Output negative pulse signal N 4 And outputting a positive pulse signal.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711412563.1A CN107834999B (en) | 2017-12-24 | 2017-12-24 | Single pulse and continuous pulse generator based on Schmitt trigger |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711412563.1A CN107834999B (en) | 2017-12-24 | 2017-12-24 | Single pulse and continuous pulse generator based on Schmitt trigger |
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| CN107834999A CN107834999A (en) | 2018-03-23 |
| CN107834999B true CN107834999B (en) | 2023-12-22 |
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| CN116047938A (en) * | 2021-10-28 | 2023-05-02 | 华润微集成电路(无锡)有限公司 | Detection chip, temperature detection system and humidity detection system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20020025749A (en) * | 2000-09-28 | 2002-04-04 | 하이든 마틴 | On-chip optically triggered latch for ic time measurements |
| CN1502162A (en) * | 2001-01-26 | 2004-06-02 | ƶ��� | Self-oscillating circuit for driving high-side and low-side switching devices with variable width pulses |
| JP2012112871A (en) * | 2010-11-26 | 2012-06-14 | Mitsubishi Electric Corp | Pulse length measuring circuit |
| CN202939188U (en) * | 2012-11-23 | 2013-05-15 | 中国西电电气股份有限公司 | Signal conditioning circuit |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN207588824U (en) * | 2017-12-24 | 2018-07-06 | 山西工程技术学院 | Pulse and continuous impulse generator based on Schmitt trigger |
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- 2017-12-24 CN CN201711412563.1A patent/CN107834999B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20020025749A (en) * | 2000-09-28 | 2002-04-04 | 하이든 마틴 | On-chip optically triggered latch for ic time measurements |
| CN1502162A (en) * | 2001-01-26 | 2004-06-02 | ƶ��� | Self-oscillating circuit for driving high-side and low-side switching devices with variable width pulses |
| JP2012112871A (en) * | 2010-11-26 | 2012-06-14 | Mitsubishi Electric Corp | Pulse length measuring circuit |
| CN202939188U (en) * | 2012-11-23 | 2013-05-15 | 中国西电电气股份有限公司 | Signal conditioning circuit |
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