Instructables

Could I use a PIR sensor as a hands free on-off switch like in 1960s SciFi movies?

I like the idea of waving my hand over a little dome to turn on or turn off an a/c device. I know a PIR can be used to actuate a circuit for a time period, but don't want the thing to turn back off until I'm ready. I would like to use the PIR to toggle on or off switch for the circuit only when I wave my hand over the sensor bulb. I'm sure this can be done, but I am not skilled enough to figure it out without a little help. I want to turn on or turn off the light on my night stand next to my bed. I could build a battery powered LED night light, but I want to use the circuit to control the a/c powered lamp. I am guessing I'd need a solid state relay or something to handle the 110 volt a/c for the lamp. Any help?

iceng1 year ago
Yes you can.

Simply replace the lamp the with a Flip-flop that powers another light.

If you need a schematic, just provide the info or ckt of your PIR device.
Purphekt (author)  iceng12 months ago
I think you've got a real good idea of what I'm trying to accomplish. A schematic would be really helpful. I scored a PIR device from Adafruit. Here is the link to the PIR. http://www.adafruit.com/products/189#Description
I would assume your idea includes the solid state relay suggested by jduff54?
iceng Purphekt12 months ago
Here is a solid state circuit complete.
You could replace the opto and triac with a solid state relay.
The 4017 acts as a flilp-flop for the output of the PIR open collector.
PIR-017-OPTOISO-sw.JPG
ariwee iceng6 months ago

gooooooooooooooooooooooooood

iceng iceng12 months ago
BTW This control concept was first seen by me in the movie
Forbidden planet and had Robby the robot
You can get a DVD of that wonderful movie for under $8.
RobbyRobot.jpeg
Purphekt (author)  iceng12 months ago
Exactly! "Robby. I beamed you and beamed you. Where have you been?"
iceng Purphekt12 months ago
Click Click Clack ..... sorry sir ..... hoping to get best answer !
jduffy5412 months ago
toggling the lamp might be a little difficult if you want it to be analog. If you don't mind microcontrollers, then you can use an attiny, and a very basic arduino program to monitor the PIR sensor and switch a relay accordingly. You could use this relay, or something similar, as long as it can take 120VAC and maybe half an amp. You will need a transistor off of the logic output of the microcontroller in order to switch enough voltage and current for the relay.
jduffy54 jduffy5412 months ago
Sorry, forgot to put up the relay link: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2077378_-1
Purphekt (author)  jduffy5412 months ago
Thanks. I knew there had to be a way of doing this project. Just a matter of tapping on the shoulder of those with more experience. My wife doesn't see the cool facter, but then again she married me.