The design and construction based on the reflection of the infrared alarm circuit, a total of two lines, when there are objects near and block infrared can send out sound and light alarm, So long as the principle diagram!!!!! Crab crab!!!!! Requirements (1) reflex of effective detection range & gt; 20 cm, (2) the system USES a single 5 v power supply, (3) as long as the target block a infrared leds only intermittent flash warning (flicker frequency definition), (4) when the target and the two infrared leds blink faster, at the same time a buzzer alarm, (using infrared tube, cannot use single chip microcomputer)
