但是有一款反激电源(MIG机控制板电源),输出28V,但是工作电流才0.5MA.
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光藕是PC817C原理图上的标示没有改过来.
带负载0.5W时震荡波形不稳定,如图
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但是带载2.5W时波形正常
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当我把电压取样边的光藕电流调整时,波形异常,并且变压器有比较大的噪音.
R14改为510欧,R13改为100欧,理论上LED电流2.5MA,光藕传输比200%(PC817C)得5MA的电流在510欧上产生2.5V压降.实际上不能正常工作.
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如果不改1K电阻的话,电路能正常工作,但输出电压高于28V的要求.
哪位大侠帮我看看是怎么回事,这个电路如果不改的话能正常工作,已经是量产的.
