应友人邀请为其设计制作了《印放像感光定时器》,制成后经试用效果甚佳,友人十分满意,现介绍如下。本定时器感光时间从1至40秒连续可调、定时准确,可根据胶卷薄厚确定感光时间,保证同一底片印放的几张照片感光量一致。并且感光灯(白)与安全灯(红)交替点亮。电路原理 At the invitation of a friend, he designed and produced a “printed image sensor”. After the trial was made, the effect was very good and his friends were very satisfied. Now we introduce the following. The timer photosensitive time continuously adjustable from 1 to 40 seconds, timing accurate, according to the film thickness to determine the photosensitive time, to ensure that the same film printed a few photos the same amount of light. And the light (white) and safety lights (red) alternately lit. Circuit theory