| 摘要 |
PURPOSE: An automatic flashing circuit for a security light is provided to achieve various types of figures and characters according to arrangement of light diodes. CONSTITUTION: An oscillation circuit(10) is multi vibrators to output a pulse wave having a predetermined cycle. A counter(20) receives an output of the oscillation circuit(10) on an input terminal, divides a counter output into output terminals(Ti-Tn) and outputs the counter output. A group of light diodes(D1-Dn) are directly connected to the output terminals(T1-Tn) of the counter(20) and turned on when there is the counter output. A switch part(30) is switched according to a condition of ambient ultraviolet rays detected and resets the counter(20). The oscillation circuit(10) includes transistors(Q1,Q2), resistances(R11-R14) and condensers(C1,C2). The transistors(Q1,Q2) are turned on by turns. The resistances(R11-R14) turn on the transistors(Q1,Q2) by performing a charge and discharge. The switch part(30) includes a photo-transistor(PT1) and a transistor(Q3). The photo-transistor(PT1) is a light receiving sensor and emits light when there are ultraviolet rays. The transistor(Q3) is switched on by being interlocked on a drive of the photo-transistor(PT1).
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