555定时器功能与应用特点

归纳了555定时器的功能,给出了一种易于记忆的简化模型,同时就其构成的无稳态触发器、单稳态触发器及双稳态触发器等应用电路的特点进行了探讨.     

Multivibrator operation in plasma-coupled semiconductor devices

A multivibrator operation based on the plasma-coupled concept is described. A triggering voltage applied to an ohmic gate located between two negative resistance elements switches the "on" state from one element to the other. Astable, monostable, and bistable multivibrator operations have been achieved by varying several circuit parameters.     

Switch-controllable dual-hysteresis mode bistable multivibrator employing single differential voltage current conveyor

This paper introduces a simple switch-controllable bistable multivibrator with dual hysteresis modes. The proposed configuration comprises a single differential voltage current conveyor (DVCC) as a main active building block with two external resistors. Both clockwise and counter-clockwise hysteresis operations can be performed using the same topology. The upper and lower threshold voltages of the bistable multivibrator can be adjusted using external passive elements. The operation of the circuit is described in detail with a discussion of the non-ideal effects and other considerations in the design of the proposed circuit. To demonstrate the feasibility of the circuit, researchers built a prototype using commercially available ICs and discrete components. Simulation results and experimental records are presented to confirm the theoretical analysis.     

Hybrid electro-optical multivibrator operating by finite feedback delay

A new type of hybrid electro-optical multivibrator is investigated. The operation principle is based on the finite delay time of the feedback circuit and the nonlinear characteristic of the light modulator. The system is analysed by a diagram technique and realised experimentally by using an integrated interferometer modulator.     

A Bistable Multivibrator as a Phase and Frequency Detector

It is very important to obtain a good noise-limiting performance and wide catching region by phase locked oscillators. In order to obtain these characteristics, a phase detector must operate simultaneously as a frequency detector. In this report it is shown how a bistable multivibrator modified for phase detector operation operates as a frequency detector as well.     

Integrated bistable optical multivibrator using electrooptically controlled directional coupler switches

An integrated bistable optical multivibrator based on two electro-optical directional coupler switches has been realised for the first time using Ti: LiNbO3 waveguides with two crossed feedback loops. The analysis and operation of the basic optical flip-flop are presented, and different feedback conditions and loops should provide other types of optical multivibrators, e.g. monostable and astable.     

声光双稳系统周期微扰反馈混沌控制研究

利用周期微扰反馈的方法,数值研究了声光双稳系统的混沌控制,通过对混沌态施加一定幅值和频率的周期微扰信号,可以将混沌态控制到不动点和周期轨道上。并用实验证明了这种方法的有效性。     

Analysis of a source-coupled MOS multivibrator with resistive drain loads

The determinant of the system of nodal equations of a source-coupled MOS multivibrator is calculated. Equating this determinant to zero, one can obtain the condition of transition from one quasistable state to another. This condition is used to calculate the currents in the multivibrator transistors at the instant of transition. Then the voltage amplitude at the coupling capacitor is calculated and the oscillation frequency is found. The oscillation frequency in this multivibrator depends on the value of currents supplied to the circuit and the power supply voltage. The results were verified experimentally.     

Stability of oscillation frequency of ECL-based multivibrator

The stability (with temperature and power supply voltage variations) of the oscillation frequency f₀ of an ECL-based multivibrator is considered. This circuit is a non-saturated multivibrator. Its operation is revised and an exact expression for calculation of f₀ is obtained. Then the temperature coefficient and sensitivity to the power supply voltage are derived. The results were verified experimentally. Some recommendations on the choice of the external timing components are given.     

Green biomass bistable transistor multivibrator

For the first time a biomass bistable transistor multivibrator using an NPN Philips transistor as the active device and freshly plucked green Champo (Plumaria rubra) leaf cuttings as electrical components (resistance R and capacitance C) has been realized. The frequency and other parameters of the generated pulses, along with the circuit configuration, are presented. The development envisages a novel march towards a green revolution in electronic circuitry.     

Dynamic performance of a tunnel-diode monostable trigger with nonlinear load

The performance of a tunnel-diode monostable multivibrator with a nonlinear load is studied both theoretically and experimentally. Analytic closed-form expressions for the pulsewidth and recovery time are obtained, and it is seen that the present results markedly differ from those obtained using simple approximations for the tunnel-diode characteristic.     

Optical bistability in semiconductor periodic structures

A theoretical demonstration of optical bistability in periodic layered media, particularly in long-period GaAs/AlAs superlattices is presented. The proposed structure consists of a periodic multilayer system, as opposed to previously demonstrated nonlinear bistable devices which employed Fabry-Perot etalons. The optical resonance effect which is essential for bistable devices is, in this case, induced by a refractive index modulation. The nonlinear active medium is distributed in the whole structure rather than placed between the two mirrors of a Fabry-Perot cavity. It is shown by a complete calculation of wave propagation in the periodic nonlinear medium that a multiple valued feature appears in the structure's nonlinear reflectivity spectrum. The input/output characteristics of the structure exhibit bistable hysteresis similar to that of a nonlinear Fabry-Perot etalon     

并联驱动声光双稳模型的超混沌控制

本文用变量反馈方法研究并联驱动声光双稳模型的超混沌控制,通过对系统的两个变量引直入相同形式的反馈项,在一定的反馈系数下,将系统的超混沌态的相空间进行了分割,压缩或控制到若干周期态,且系统各变量均可被控制到相同的周期数目。     

A matrix addressable bistable nematic liquid-crystal display with electric field writing and thermal erasure

We describe the fabrication and performance of a 20 × 40 element bistable liquid-crystal display using a dye guest in a nematic host. The bistable configuration ensures the long term memory of the written display. The electrical writing procedure together with the use of segmented subpels produces sharp, uniform switching thresholds resulting in clearly written displays with good contrast. Both 2:1 and 3:1 matrix addressing schemes are possible. The thermal erasure scheme is discussed in detail and the influence of the boundary aligning material and the resulting nematic director tilt angle is investigated both theoretically and experimentally. Results are presented for both reflection and transmission displays.     

Switching characteristics and maximum repetitive frequency ofInGaAsP/InP bistable injection lasers

Switching characteristics of nonuniformly pumped InGaAsP/InP buried-heterostructure bistable lasers are investigated both experimentally and theoretically. The automatic turn-on phenomenon, which is a random process, was observed. For repetitive operation, turn-on delay time and the necessary duration of the switch-off pulse practically limited the maximum repetitive frequency. For switch-on, triggering the saturable absorption region is more effective. For reducing the minimum switch-off pulse width, either higher doping of reverse biasing at the absorption region is recommended. The tradeoff of OFF pulse width with threshold current, and stable operation are discussed. With some improvements in device parameters, bistable operation at a repetitive frequency over 1 GHz is expected     

Integrated astable optical multivibrator using Mach-Zehnder interferometric optical switches

An integrated astable optical multivibrator has been analysed and demonstrated experimentally for the first time using a couple of Mach-Zehnder interferometric optical switches with crossed and straight electronic feedback. Fairly good agreement is found between experimental and analytical results.     

切换式双波长激发在掺镱和铒镱共掺复合式光纤激光器中的实现

抽运旁通腔型的掺镱光纤(YDF)激光器内剩余的抽运光功率随着入射抽运功率的变化呈现出光学双稳特性,这导致了用它来抽运另一个分叉腔的铒镱共掺光纤(EYDF)增益介质可获得第二个信号波长激发的可能性。根据这一原理,从实验上获得了1040 nm和1537 nm两个激发线的可切换振荡,这表明基于掺镱光纤激光器光学双稳态的复合腔结构(掺镱光纤激光器的抽运旁通腔和铒镱共掺光纤分叉腔)是实现切换式双波长光纤激光器光源的一个简单有效的方法。     

考虑几何非线性时双稳态压电悬臂梁响应分析

针对双稳态压电振子产生大挠度振动现象,利用哈密顿原理建立了其大变形动力学方程,再用Galerkin法将其离散为模态坐标方程。对无量纲化方程进行数值分析可知:在激励一定下,存在最优阻抗使输出功率最大;在相同的激励水平下,大幅周期运动发电能力优于大幅混沌运动;通过对比发现几何非线性使系统产生更多的混沌窗口,改变梁长可使系统处在大幅周期运动中,从而提升压电发电能力。     

LD/PIN光学双稳半导体激光器的临界慢变效应和临界指数

一、引言 当光学双稳系统靠近临界输入光强时，开关时间会趋向无穷大，这就是临界慢变效应，它不但在理