500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/66/1079811212990212.gif');}" onmousewheel="return imgzoom(this);">请教一个关于振荡升压的电路
请教该电路的升压工作原理,12v_all经过L21后,通过Q21振荡,D57整流CA30滤波后变成33v输出,请教高手帮分析下Q21周围的电感L20,L23,C151,C155是起什么样的作用?与模电的电感反馈三端,或电容三端反馈振荡有什么样的关系,谢谢!500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/66/1079811212990212.gif');}" onmousewheel="return imgzoom(this);">
500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/66/1079811212990212.gif');}" onmousewheel="return imgzoom(this);">