555 brightness adjustable indicator light circuit

Published:2011/5/21 9:33:00 Author:TaoXi | Keyword: brightness, adjustable, indicator light | From:SeekIC

In some conditions we need the brightness adjustable indicator light, if we uses the resistance step-down method, the power consumption is large. This circuit uses the variable duty cycle oscillation square-wave to supply power, this method can adjust the brightness of the light, and can save the power. As the figure 17-42 shows, the astable multivibrator is composed of the 555 and R1，R2，RP1，C1. The oscillation periods are: T=0.0693(R1+R2+RP1)C1t(charging)=0.693R2C1t(discharging)=0.0693(R1+RP1)C1 By adjusting RP1, we can change the t(discharging) which means the lighting time of the lamp.



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