Automatic Light Switch- for Better Home Efficiency

About: I like regular robotics and combat robotics. I also like just about anything that has to do with instructables.

This switches the lights on when you enter the room and turns them off when you exit. It is made using a nxt mindstorms kit. The video shows the lights switching on and off when I enter and exit. It can tell when someone walks in because it has an ultrasonic sensor. The program is the last file.

Step 1: Building the Mechanism

It is basically just a reciprocating mechanism. It is very simple and it is taped to the wall. Also the way that the bar keeps from falling is a piece of backwards tape, taped over by a piece of frontwards tape.

The ultrasonic sensor is mounted to the nxt brick.

If enough people show interest in this project I will probably make a lego digital designer file (that's kind of like cadd but for legos)



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    7 Discussions


    3 years ago on Introduction

    Good project, but might be improved if instead of turning off when you leave or if someone else walks in, just have it turn on when it detects movement, and then after so long of no movement, turn off.


    5 years ago on Introduction

    Its a nice project here. But, just asking, does the ultrasonic sensor has any harmful effect on us..?

    2 replies

    Reply 5 years ago on Introduction

    I don't think so. Ultrasonic sensors just uses sound waves that are at a frequency higher than the human ear can detect.


    8 years ago on Introduction

    If your going for efficiency wouldn't a simple relay work just as well.


    8 years ago on Introduction

    The idea is good. But the NXT has to be turned on all the time aswell... what uses more energy?

    1 reply

    I 'm not sure what uses more energy, but it was more of a "proof of concept" project.  There was also a logistics problem, if someone else walked in the room, then the lights would shut off.  It could be fixed by having two sensors, so you could tell if someone was leaving or coming in.  Also with a variable that stored how many people were in the room it would prevent the lights from shutting off on the people in the room when one person leaves.  So then the lights would only go out if everyone has left the room and the variable is equal to zero.

    Thanks for the comment