Photo sensor for PC

Question

This may be strange request but still..

We have timeout in office lights system where they switch off after period of inactivity.When it happens, I have to interrupt my work, get up and wave my hands at stupid ligths in the ceiling to get them switched on.This is especially annoying (and looks stupid too) in early hours when it it still dark in the office.I have already asked building management to switch off the timers during the office hours but they are not interested.

My idea is to put the small old pc on the top of the cupboard , then attach one side of thin thread to the ceeling next to the sensor and another one to the cd tray.Then stick little bit of hard paper to the ceiling end.Write short script that opens/closes CD tray. When CD tray open/closes, piece of paper moves and switches lights on.

Then I need to get some device that can be attached to the PC and it would start the script whenever it detects light.

What should I look for on ebay? 'photo relay'? 'photo swithch'?

Answer 1

WOW.... so much work just because the building-mamagement doesn't want to change this? Do they have a reason for this? But anyway:

You could just use a webcam but you will need a program which starts a script, when it detects light-change / tun off.

Or would it also work, if the computer opens or closes its dvd-drive for example every 10 minutes (depending on the light-off-settings. I think this solution - to just change the dvd-drive-open-state periodically will be easier and cheaper then the react to light-idea ;-) If you want I can write you a little application which does exactly this tomorrow /in ~ 17 hours.

Also I think this question should be on stackoverflow.com or superuser.com, and not here.

Answer 2

the sensors usually are IR light sensitive. get yourself a flash led device (toy or whatever you can buy and that flashes at least one led) and replace normal led with IR led. attach it close to the sensor. see what happens :)

Answer 3

You don't need anything as complicated as a photo-relay or webcam! Work out how long the delay required for the lights to shut off by timing it and then add a slightly shorter timer to your program. Open the program when you want the lights to stay on/put it on a shedule and job done.

Sometimes when you start thinking about a complicated solution, it is easy to miss the obvious.

Answer 4

The problem with the delay idea is that time periods are not the same.Sometimes people do walk by , especially during the daytime and this resets timer to zero.

Answer 5

A small gear motor with a slow rotation and an arm at right angles to the shaft could pull the thread as it constantly rotates. You could power it with a wall transformer and it would draw less power than running a PC. It would also be less jarring than having the noise of the CD tray interrupt your concentration every few minutes.