The limitations of Schmitt toggle circuit, composed of 555 timing circuit, is discussed, a improved Schmitt toggle circuit is given, and proved by using theory and experiment.

• 摘要论述了常用555定时器构成的施密特触发器电路的局限性，给出了施密特触发器的改进电路，并用理论和实验加以证明和验证。