Electronics Turn Your PC on when you walk into your machine room....

I'm working on a project to turn my machine ON when i walk into my machine room. I can walk freely in and out when its ON without fear of it turning OFF.

When I want to turn it off i just stand in my doorway for about 4 secs until i hear my pc power down (walking pausing a moment then continuing).

I intend to use this design:

I had a moment of ispiration and ran a few tests and it worked.

The LASER MODULEs are obtainable from RAPID and MAPLIN or can be obtained from an old laser pointer (most of us have got one we never use laying about).
The Laser projects light on to the LDR; when a person breaks the beam the MoBo Power header is triggered through an opto isolator.
The red filter stops 'white light' getting to the LDR and preventing its proper operation.

I had this idea weeks ago but only just got round to testing it; i should have pics in a week or two.

(You may want to disable some power settings in power management in windows if you down want your PC to suspent evrytime you leave the room. I indent to add an overide button that you can hit as you pass the sensor to stop the PC from powering up in case i'm just nipping into my room for a print-out or pen or something.)

 

"White Light" is composed of the entire spectrum, there will be red in it, your best bet might be IR.

Cool Idea though, having said that if I had a room for my PC's they would prolly only ever enter suspend mode so what bout using a keyboard and wiring it up to the suspend key? that way it would power save whenever you left the room (ok 30 second might be a bit silly but thr ideas sound)

 

COOL !!!!!

GeeK!

 

but do u really want your computer 2 turn off if your just getting a drink or something cuz pressing an override button would be annoying

 

no he said you wont have to overide when leaving, but if yous tand in the doorway for more than 4 seconds it powers down

on the subject of the white light/ir issue if you encased the parts in pvc pipe sprayed matte black and left a few inches of pipe protruding over the sensor, then only light from a specific angle would set it off, right?

 

The amount of red in 'white light' is neglagable as the transistor circuit is not sensitive enough for it to make a difference.

On the suspend thing; you can set windows to enter suspend mode when a momentary pulse is sent to the power header (i.e. pressing the power switch once or just walking past the sensor)

 

A small amount of sunlight shining through the red filter will be brighter than the laser diode. I think infra-red would be better too. Even more reliable if you set it at a given frequency.

 

Very simple, Mount the sensor in a small 2 inch tube.
Use the red filter also if you wish.

 

I was thinking of doing something like this except until I realised that since I left my pc on 24/7 it would be wasted
I was thinking about using a pressure sensitive mat which would have worked in a very similar way to your laser module.
It would be even cooler if the laser was visible in daylight

 

the sunlight will give you just as much IR trouble as Red... We were doing an IR following robot that would get screwed up if the sun was shining too hard in the room and the sensors were too far from the surface...

As people have said use a little tubing to put the sensor in a shadow...

and for DaSuperFly, add a low volume fog generator

 

Another way

Take a look at this company:

http://www.greenweld.co.uk/

They do surplus electronics. Last time I checked, they had some cheap pressure sensitive mats in, the kind used for security systems. Place one under your carpet or doormat (yeah, my room has a doormat ) and away you go.

As for wake-up methods, maybe wake-on-ring would be easiest since it just required control of one line on an RS232 port, AIUI.

I was maybe gonna try the pressure mats to turn my light on when I enter my room.

MoJo

 

ultra sonic perhaps. have a US range finder and if the range suddenly decreases turn on/suspend. if it decreases for x amount of time turn off. Would have no problems with light and probably none with sound, unless you have bats or mice or something. but you could probably get around that by narrowing the frequency.

 

Just a suggestion: use the wake on LAN header instead of power. That way you don't accidentally turn it off.

 

Hey acrimonious, Hows things??

Just refering to you Lazer switch and the question I asked about weather it could be hooked to say a rooms lighting socket, well i have some more querys


Could it be possible to hook up some design that would be able to recognise if a person was enetering or leaveing the room, so if a person entered the room then 5 mins later some one else did it wouldnt turn off the light.

And could you make it some how count the amount of people entered the room so as to turn off the light when all person has left the room

Russ

 

to solve all the above: you could have a dual sensor arangement (one in front of the other) to sense if someone was leaving or entering with a couple of latch circuits. I suppose you could set it up so the system would only switch off when the room was vacated by counting the no. of people in the room.

But for all that effort isn't it easier to use the light switch?

 

A light switch, in this day and age....nah, bring on the funky stuff. Dont think they would be anyone else in my street (in the town in fact) with lazer switched light

Who da man, who da man lol

 

So then, I take it you would use the circuit you made but double it so it dual senses. And you would need to add a counting device and memory circuit.....any circuit ideas there.

Also, your light circuit runs at some funky current, so you would need a relay that was able to be activeated by the small power from the sensors, and turn on the 20 amps (or is it 40amps) of the lighting circut. Also you would the sensors to have an over ride switch some where (say for parties or something, you dont want the poor circuit counting loads of people going in and out of the room!!!!)

 

The best idea could possibly be using a small ultrasound detector/reciever combo and an opamp to boost the signal. A small latch shouldn't be that difficult or if you have the use of a pic programmer then making it do the counting for 4 seconds shouldn't be hard either. The hardest bit would be making your own PCB and getting the resistor values right

 

Imagine if someone is keeping 4 seconds in your computer room door when you're working on something important

 

My TV used to turn on early in the morning durring the summer if the curtains were open.

It was never realy a problem, but it took us a while to realize why the TV was turning on... Ghosts? Or maybe... The SUN!