555定时器是一种模拟电路和数字电路相结合的中规模集成器件，它性能优良，适用范围很广，外部加接少量的阻容元件可以很方便地组成单稳态触发器和多谐振荡器，以及不需外接元件就可组成施密特触发器。因此集成555定时被广泛应用于脉冲波形的产生与变换、测量与控制等方面。-555 timer is a kind of analog circuits and digital circuits combined with the medium-scale Jicheng device, its excellent performance and broad scope of application, Waibu plus a small amount of resistance Yung Jie components 可以 easily Zucheng Shan steady trigger and multivibrator devices, and external components can be formed without Schmitt trigger. Therefore, time integration of 555 pulses are widely used in the production and transformation, measurement and control and so on.