555 discoloration electronic brooch circuit

Published:2011/5/30 20:52:00 Author:TaoXi | Keyword: 555, discoloration, electronic, brooch | From:SeekIC

This electronic brooch circuit uses the double time base integrated circuit 556 as the core. It changes the color automaticly and has a lots of colours. The circuit is as shown in figure 15-47. The astable multivibrator is composed of the IC1-a(1/2 556) and R1，R2，C1, the oscillation frequency fc=1.44/(R1+2R2)C1, it is about 1Hz. The multivibrator is composed of the IC1-b(1/2 556) and R4，R5，C4, the oscillation frequency is the same as the IC1-a's oscillation frequency, the difference between the them is only 0.0027Hz. When IC1-a outputs the high electrical level, the LED1 issues the red light; if the IC1-b outputs the low electrical level, LED2 turns off, the whole glowing tube shows the red color.



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