555 variable delay lighting auto off light circuit

Published:2011/5/21 7:58:00 Author:TaoXi | Keyword: variable, delay, lighting, auto off light | From:SeekIC

As the figure 17-36 shows, this circuit is composed of the step-down rectifier circuit, the boot timing circuit and the SCR control circuit, and it can be used in wide range of applications such as the floodlight of the staircases and corridors. The step-down rectifier circuit's VDD=+9V, it supplies the DC current to the controller. The boot delay circuit is composed of the IC (555) and R1 ~ R4, C1, the monostable time depends on the position of the timing switch K. The delay time td=1.1RC1. When the delay time is over, 555 resets, SRC cuts off, the light bulb H automatic turns off. The delay time is between one minute to ten minutes and it depends on the time constant RC1.



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