555 disabled person three-purpose electronic circuit

Published:2011/5/25 4:05:00 Author:TaoXi | Keyword: 555, disabled person, three-purpose, electronic circuit | From:SeekIC

As the figure 16-4 shows, the three-purpose electronic circuit uses the 555 as the core, it has the following functions: Wake-up function: X connects to the electronic alarm clock chip, in peacetime X is the opening circuit, K3 is in the position of contact point a. When the timing time is up, X adds the voltage to pin-4, so 555 starts working, the oscillation frequency f1=1.44/(R2+2R3)C2. Eyesight exercise: if you close K1 and K2, then move K3 to the b contact point, so 555 forms the multivibrator which has the frequency of 1Hz, the figure parameter's oscillation frequency is about 1Hz. The blind man water detection alarm: if you disconnect K1 and K2, and move K3 to the C port, then install A, B at the bottom of the cane, when you are working, if the bottom of the cane contacts the water, pin-4 has the high electric potential to make 555 in the oscillation state.



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