近日接修了几台学生的台灯,经询问都是在换灯泡时损坏的台灯。经检测均为可控硅损坏,经分析电路(如图1),发现此电路设计有缺陷。它是利用 RC 移相网络,RW、C 来调节可控硅 VS的导通角以达到调光的目的。R1作为可控硅的限流电阻的同时,还与 R2串联为 C 提供放电通路。 Recently, a few students to take over the table lamp, after asking are the lamp in the damage when changing the lamp. After testing are SCR damage, the analysis of the circuit (Figure 1), found that the design of this circuit has flaws. It is the use of RC phase shift network, RW, C to adjust the conduction angle of SCR VS to achieve the purpose of dimming. R1 as a thyristor current limiting resistor at the same time, but also with R2 in series to provide discharge path C.