Bar code reading circuit

Published:2011/4/28 1:33:00 Author:Nicole | Keyword: Bar code, reading | From:SeekIC

This circuit is sensitive to edge, every change from black to white or white to black will output narrow pulse; the timing figure shows that it is in accordance with the bar code parrent output. Whatever temperature, environmental lighting or pattern background is, DC servo remain Q1 base's DC level comstant. It also can use photodiode and 2N2222 transistor as sensor to enlarge the width. The amplified differential signal produced by Q2 collector is magnified further by IC2, feeding it to double threshold value comparator. About each mutation, the comparator will output a narrow pulse, this narrow pulse is suitable for feeding to microprocessor.



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