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Need help with Electronics....

  • 17-12-2005 1:33pm
    #1
    utilitarian
    Registered Users, Registered Users 2 Posts: 36 ✭


    hi there, i really hope that i do not step on anyones toes by asking this in the wrong section, i have an electronics question. this seems to be the closest thing to electronics that there is, am i not seeing it?

    Anyway, my question is, i want to make a little battery powered light come on when the lights go out. Something like like the opposite of an LDR (Light Dependant Resistor). With an LDR, if you block the light from the LDR the light will go off... i want the opposite to happen, not with an LDR obviously, but with whatever piece of electronics that can do it.

    Any brains out there could help me?

    Donal


Comments

  • #2
    ozt9vdujny3srf
    Closed Accounts Posts: 3,152 ✭✭✭ozt9vdujny3srf


    EDIT: What you need is an LDR and a 311 comparator. Both can be purchased at peats. Google for a detailed how-to or if you cant find one then PM me your mail address and I'll see if i can find an old lab i did on this.


  • #3
    utilitarian
    Registered Users, Registered Users 2 Posts: 36 ✭utilitarian


    tuckle, this sucks, i have googled the 311 comparator and LDR, but i still do not know much more than i did this morning. There was a seemingly excellent site but the link wasn't working.

    could you email any info to me, my gmail addy is

    donalod@gmail.com

    Yesterday i bought an LDR and connected it to a battery and an LED and to my disappointment i realised that when i covered the head of the LDR the LED would go off, and i was thinking, man this sucks.

    What i want to do is a thing where if the lights go off in the house, that this thing i want to build will come on and via a few batterys that a little bulb will light up... it will not be much light, but it will be a little, and that is all i want.

    Just to make sure that i have explained the whole thing properly. Thanks again, and if there is any sites you like, i would love to see them, i am just learning about electronics.... if your looking to take on a padwan style student, you just found one...

    Donal


  • #4
    smeggle
    Closed Accounts Posts: 519 ✭✭✭smeggle


    why not get one of those garden solar lights and canabalise that? They have the switch built in that does that. Though it charges a battery during the day just disconnect that bit for what you want and replace the battery with standard non chargables.

    Hook your light into the circut that would switch it on as soon as the light drops to a certain level (i.e. dark) and job done so to speak...

    What I would do anyway :)


  • #5
    Balfa
    Registered Users, Registered Users 2 Posts: 1,709 ✭✭✭Balfa


    http://www.google.com/search?q=light+dependent+resistor

    Have you ever thought googling for light dependent resistor? Because, y'know, the very first match tells you exactly what you need to do :rolleyes:


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