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Laser Burglar Alarm -- Need Help

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by Anonymous321, May 4, 2008.

  1. john1

    john1 Active Member

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    do you have some transistors to choose one ?
    please describe, thank you.
     
  2. john1

    john1 Active Member

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    do you have a camera or webcam,
    so we can see your layout, ?

    John :)
     
  3. john1

    john1 Active Member

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    You have to 'Refresh' or come back to the page to see the replies.
    (you may know that)

    John :)
     
  4. dave

    Dave New Member

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  5. Torben

    Torben Well-Known Member

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    Sorry, anon. 'LDR' means light-dependent resistor; it's just a resistor which changes value depending on the amount of light falling on it. Also referred to as 'CdS cells'.

    'Vcc' is just another way of saying 'V+' or 'the positive supply voltage'.

    You got the 'pot' in one. :)

    You can get Darlingtons either as a single component (looks just like an ordinary transistor) or you can make your own with two transistors. Google 'Darlington wikipedia' for more information.

    Mmm....I am away from my gear right now so I can't test that, but I have a feeling it won't work as well as you might hope.

    Ah, gotcha. OK, skip the output timer. The inverter is just one transistor and a resistor configured so that the output is the inverse of the input, and a 555 is just an 8-pin timer chip which is ridiculously useful. ;) If you just need to prove the concept of causing your buzzer to buzz, no matter how briefly, when the beam is broken, you can safely ignore the inverter/555 thing I mentioned.

    What town are you in? There may be something besides The Source (even worse than Radio Shack if that is possible). Heck, in a pinch you might be able to give a local TV repairman $10 for a few bits and pieces; you never know.

    Is the purpose of the exercise to show that you can design the actual circuit, or just to show that such circuits *can* be built from plans? If the latter I could just post a link or a schematic for you.


    Good luck,

    Torben
     
  6. john1

    john1 Active Member

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    Are you assembling this on one of those 'breadboard' kit things,
    with rows of holes that you poke the bits into ?

    John :)
     
  7. john1

    john1 Active Member

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    please refresh
     
  8. Anonymous321

    Anonymous321 New Member

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    Yes, I have a multimeter. It's a Mastercraft Pocket Analog Multimeter.
    Specifications:
    DCV...............10 V/250 V/500 V (2 K:eek:hm:/V)
    ACV...............10 V/250 V/500 V (2 K:eek:hm:/V)
    DCA...............500:mu:A/10mA/250mA
    :eek:hm:.............2K:eek:hm:/200K:eek:hm: (centre 3.6 K:eek:hm:)

    Yes, I also have resistors. 3 packs.
    1st pack:
    1/4-watt, 5% Carbon resistors, 2-pcs of each
    10, 22, 33, 47, 220, 330, 470, 1k, 2.2k, 3.3k, 4.7k, 10k, 22k, 33k, 47k, 100k, 220k, 330k, 470k, 1m ohm

    2nd pack:
    1/4-watt, 5% Carbon resistors, 5-pcs of each
    100, 220, 330, 470 ohm

    3rd pack:
    1/8-watt, 5% Carbon resistors, 5-pcs of each
    10, 22, 33, 47, 220, 330, 470, 1k, 2.2k, 3.3k, 4.7k, 10k, 22k, 33k, 47k, 100k, 220k, 330k, 470k, 1m ohm

    So obviously lots of the same ones. I bought pack 1 and pack 3 b/c they were different watts. I didn't (and don't) know which one would be best.

    Yes, I have transistors to choose. 2 packs.

    1st pack:
    On the front of the pack, it says NPN-Type Switching Transistors.
    On the back:

    Silicon..........NPN
    Typical hFE...200

    Maximum ratings
    VCE.............30V
    IC................800mA
    Dissipation.....1.8W
    Then it tells me that these are designed for high-speed, medium power switching and general purpose amplifier applications. And then it tells me which leads are the B, C, and E.

    2nd pack:
    On the front of the pack, it says PNP Transistors and that they're "Similar to type 2N3906".
    On the back:

    This 2761604 is designed as a general purpose amplifier and switch. The useful dynamic range extends to 100mA as a switch and to 100 MHz as an amplifier.
    Collector-Base Voltage........60V
    Collector-Emitter Voltage.....40V
    Emitter-Base Voltage..........6V
    Dissipation........................350MW
    Then it describes which pin is the B, C, E.

    And, unfortunately I do not have a camera or a webcam. My cousin has them and I suppose he may be able to lend one of them to me...What about skype?

    And sorry for the late reply.
     
    Last edited: May 5, 2008
  9. john1

    john1 Active Member

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    thats Ok.

    I'm thinking now.
     
  10. john1

    john1 Active Member

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    are you using one of those 'breadboard' kit things,
    with rows of holes that you poke the bits into ?
     
  11. john1

    john1 Active Member

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    Can you tell which pins are which on the transistor(s)
    This is necessary.
     
  12. john1

    john1 Active Member

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    please refresh
     
  13. Anonymous321

    Anonymous321 New Member

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    No, none of the Sources had them. They had PC and IC boards but I believe I'd need to solder and I don't even have soldering material let alone know how to solder anyway.

    But I am using steel springs to connect my wires. It's just this cardboard box with small holes that many small steel springs are inserted in. And I just put my wires on those springs.
     
  14. Anonymous321

    Anonymous321 New Member

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    Torben -- "Is the purpose of the exercise to show that you can design the actual circuit, or just to show that such circuits *can* be built from plans?"
    Not even any of those. It's just to do a research project and build any model. It's not even related to circuits. It's an open project and I wanted to do mine on alarm detection methods. Like, some girl in my class today presented and she did her project on quarks. Her model was just like a sock with two styrofoam balls in it. Of course, she did get pretty much destroyed by the teacher though..

    John -- Which pins are on the transistors? Well um, Pin 1-Emitter, Pin 2-Base, Pin 3-Collector. Is that what you mean?
     
  15. john1

    john1 Active Member

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    Okaay ...

    got to feed my cat, she's actually rattling her dish.
    Back v soon
     
  16. Anonymous321

    Anonymous321 New Member

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    Torben--Well it's a small town near Lake Huron in Ontario. And it really doesn't have much. Anything useful has probably already closed by 6pm (atleast The Source and our local internet provider store, which I believe closes at 5).
     
  17. Anonymous321

    Anonymous321 New Member

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    If it's really needed, I can try to get a camera. One of my friends may be able to lend me one. But also, what about msn messenger or skype?
     
  18. john1

    john1 Active Member

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    are they like this ?
     

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  19. john1

    john1 Active Member

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    If you can borrow a camera,
    it would help,
    but i think we'll struggle through.

    John :)
     
  20. john1

    john1 Active Member

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    refresh .....
     
  21. blueroomelectronics

    blueroomelectronics Well-Known Member

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    Mastercraft? You must be Canadian.

    How about taking apart one of those solar lamps, cheap and have most of the parts you'll need.
     

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