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Laser or IR beam alarm system

Discussion in 'Electronic Projects' started by zachtheterrible, Dec 13, 2004.

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  1. mrkedar_kyk

    mrkedar_kyk New Member

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    as..... ordinary

    your project was really amazing
    i like it very much.
    :)
     
  2. Amarr

    Amarr New Member

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  3. tmurali

    tmurali New Member

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    could you give the values of pnp and npn's
     
  4. dave

    Dave New Member

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  5. henok

    henok New Member

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    what is the value of the transistors
     
  6. henok

    henok New Member

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    hello

    hi how are you i am from ethiopia & i am electronics student .
    i really need to know the values of the transistors.
     
  7. slamslam123

    slamslam123 New Member

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    power line communication

    hi guys . if any person has information about the voice over power line, please give it to me
     
  8. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Page 2 of the thread.
     
  9. KlatuClassic

    KlatuClassic New Member

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    Hey Zach, I am in Temecula and would like to pick your brain about the beamed alarm idea. Are you still around? Jim
     
  10. DarkFel

    DarkFel New Member

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    Yes, sorry, I'm not English, But I try to speak my mind :
    I tested your circuit on my computer with the following program : crocodile physics, it works perfectly, but I don't know what's transistors I need to do it... 2N2222 and 2N3904 could be work ? Thanks :)
     
  11. Torben

    Torben Well-Known Member

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    Hey there,

    Look, you're welcome on the forum, but if you have a business to advertise then just but a nice discrete link in your .sig and only post relevant posts. This is not a place to advertise, it is a place to learn and to teach.

    Be polite, don't spam, and don't post in threads unless you have something to add to the discussion which is already happening. Don't start your own threads if the only point is to spam us.


    Torben
     
  12. elitesky

    elitesky New Member

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    Hi masters, can I ask something? What kind of laser is strong enough to trigger an LDR? Ive been thinking of a simple cheap laser pointer which is battery powered but I wonder if its strong enough to trigger an LDR placed about 2 feet away. And does anyone have an idea of a kind of laser that can be plugged to an outlet? because the battery-powered one cannot last long and becomes weaker. Because i also have a project, its an obstacle scanner. the LDR and laser is mounted on opposing conveyor belts, and the space is between is scanned for obstacles. thank you in advance :)
     
  13. Torben

    Torben Well-Known Member

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    Hi there and welcome to the forums,

    First off, I am a master of nothing except perhaps my own boots. :) That said, a cheap laser pointer will be more than enough to use with an LDR. It will depend a lot upon the circuit and the actual LDR in question, though.

    Can you post the schematic you intend to use?


    Cheers,

    Torben
     
  14. elitesky

    elitesky New Member

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    i still dont have schematics. we havent started doing it, since it is in proposal stage and we are deciding what materials to gather. and im no electronics practitioner, it is a part of our project in parallel port interfacing. the laser and LDR is moved horizontally on separate conveyor belts to scan a surface. so basically, the LDR and laser should be far apart about 2 or 1.5 feet. here's the setup in the attachment..
     

    Attached Files:

  15. Torben

    Torben Well-Known Member

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    LDR should work fine, although I'd probably use a phototransistor as a receiver instead of the LDR. LDRs are slow compared to phototransistors. Photodiodes are faster yet, but I have LDRs and phototransistors around and no photodiodes.

    You will need to account for ambient light rejection, so the receiver will need to be shielded and you might want to look at modulating the laser so that ambient light won't interfere. Shielding is easier if you're not that into electronics though.


    Torben
     
  16. elitesky

    elitesky New Member

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    yeah we are planning to remove as much ambient light as possible by shielding the LDR, or the whole setup itself. thank you for ur suggestion ^^
     
  17. ia123

    ia123 New Member

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    i know this is jind of stupid question. Im in year 10 and making several sequrity systems for my GCSE grade. How can i make the buzzer go on indefinetly untill the circut is reset?
     
  18. dead_man

    dead_man New Member

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    Laser Or Ir Beam

    wht is the number/name of the transisrte you used in the cicrut.plz let me now quick
     
  19. ia123

    ia123 New Member

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    fixed it

    I found if i just stuck a high value capistor there then it went on for virtually ever. well long enough for some one to hear. Thx anyway
     
  20. xanne0037

    xanne0037 New Member

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    i am a computer engineering student.. i need this kind of circuit too for my school project. is it possible to supply a laser pen by an AC power so it will be plugged in not worrying about it's battery?

    is LDR doesn't have any code description? i mean, do suppliers will give what i need by simply asking for an LDR?
     
  21. Dirka21

    Dirka21 New Member

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    Yes you can connect it up to a transformer, but first you need to check the ratings of the laser pointer, i.e. what the max amount of voltage is it can take. Than if you only have tranformer with a certain output which is not the output you want, you willl have to incorperate a step-up or a step-down circuit to get the voltage up or down.

    To the locals, sorry not trying to revive this thread or anything. I was just doing some research and looking into this thread since I also want to do this project. once I'm done with mine I'll post it here, may take a while so please be patiant. Just a word of respect for you guys for all your patiance. Hope you all have a great day.
     
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