笔者参阅有关资料并加以改进 ,自制成一台正负电荷检验器 ,其特点是成本低 ,结构轻巧 ,具有直观、醒目的“ +”、“ -”字符显示功能 ,极大地提高了白天教室演示的可视度 ,效度好 .1　触发放大电路完整电路如图 1 .有关用ＮＥ5 5 5组成单稳态延时电路的工作原理请参阅有关资料 I refer to the relevant information and improve it, since the creation of a positive and negative charge tester, which is characterized by low cost, light structure, intuitive, eye-catching “+”, “-” character display, greatly improving the daytime classroom The visibility and validity of the demonstration is good. 1 The complete circuit of the trigger amplifier circuit is shown in Fig. 1. For the working principle of the monostable delay circuit composed of NE5 55, please refer to the related materials.