1. Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
    Dismiss Notice

Laser Burglar Alarm -- Need Help

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

  1. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    She's getting on now, nearly twenty years old.
    I tell her its white wine when i put her milk down,
    and i tell her its sparkling mineral water when i top up her water.

    She's not impressed.

    please refresh.
     
  2. Anonymous321

    Anonymous321 New Member

    Joined:
    May 2, 2008
    Messages:
    93
    Likes:
    0
    Those are the PNPs, since the emitter is going in. Yeah, mine are like that (they're shaped like the one with the straight leads). But the Collector-Base is 60V and the Emitter-Base is 6V on mine. Although I think you were just trying to verify the shape. Also, in my circuit, I was trying to use one of the NPN transistors that I have. Both types of transistors that I have are shaped the same way.

    And I'm trying to get a camera.
     
  3. Anonymous321

    Anonymous321 New Member

    Joined:
    May 2, 2008
    Messages:
    93
    Likes:
    0
    Lol, and I am refreshing. It's just I'm typing when you're telling me to refresh.
     
  4. dave

    Dave New Member

    Joined:
    Jan 12, 1997
    Messages:
    -
    Likes:
    0


     
  5. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW

    yes thats fine.
    1 emitter, 2 base, 3 collector,
    with the flat on top,
    and the pins pointing toward you,
    Ok.

    Have you tried the buzzer on the battery,
    is it Ok ?
     
  6. Anonymous321

    Anonymous321 New Member

    Joined:
    May 2, 2008
    Messages:
    93
    Likes:
    0
    Yes, it is ok.
     
  7. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    About the refresh,
    its just too easy to forget.
    But thanks, and i'm sure you already know that.

    John :)
     
  8. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    i dunno quite what these springs are about,
    so maybe i should draw a bit to try ...

    has this spring box thing got a name?
    could i find it on google ?
     
  9. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    I think that siren will only work one way round,
    i spose its marked, yes ?
     
  10. Anonymous321

    Anonymous321 New Member

    Joined:
    May 2, 2008
    Messages:
    93
    Likes:
    0
    The spring box is just a cardboard box. With holes in it. And small springs are inside it. They're just small steels springs and I decided to like crunch my wires in between the springs instead of taping my wires with duct tape.


    "I think that siren will only work one way round,
    i spose its marked, yes ?" I don't understand? Work one way round? Marked?

    http://www.thesource.ca/estore/Prod...nline&category=Chimes_Buzzers&product=2730059
    That is the link for my buzzer. I wrote the specifications earlier too.

    And I'm going to go buy a cheap $30 digital camera. Every one I called seems to have theirs "broken". What luck. Just more stress.

    But John, would you also happen to have Skype or something so we could talk as well? I dunno, it'd just be better for me to listen to what I have done wrong.

    But anyway, brb with the camera.
     
  11. crutschow

    crutschow Well-Known Member Most Helpful Member

    Joined:
    Mar 14, 2008
    Messages:
    10,623
    Likes:
    479
    Location:
    L.A., USA Zulu -8
    ONLINE
    If I understand correctly when the transistor is off, the siren is off. To turn the transistor off you apply less that about 0.6V to the base.

    To turn the transitor on requires a current into the base emitter junction (it looks like a forward biased diode). Thus the base emitter voltage will be about 0.7V when applying base current.

    Does that make sense?
     
  12. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    No, Sorry,
    I have no mike, i do intend to get one and fix up one of the voice systems.
    But it will have to wait.

    Also i think this sort of thing is best done in the open forums.

    Okay, i looked at the picture of your buzzer/siren.
    Yes, one lead is red, that is to indicate positive.

    The chances are if you tried it the other way round, that would bust it.

    Here is a little picture i have drawn.
    Before you put it together with springs, are the springs spaced decently apart?
    we dont want any of them touching each other.

    The wire you may be using ...
    is it insulated wire, which you bare the end a little way for the contact ?

    Its not just lengths of bare wire is it ?

    Do you reckon you could link up the siren and a transistor like that ?
    If you do so it should not operate the siren yet.

    John :)
     

    Attached Files:

  13. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    going to tend to my dinner now
    be right back
     
  14. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    I'm back.

    You there ... ?
     
  15. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    guessing you are 5 or 6 hours behind the time here ...
    so maybe you are having dinner ?

    thats Ok, i will just refresh every so often until i get fed up ...
     
  16. Anonymous321

    Anonymous321 New Member

    Joined:
    May 2, 2008
    Messages:
    93
    Likes:
    0
    I'm back with the camera. A little more expensive than I thought but if this works in the end, it'll be worth it. Have to install some drivers rather...-_-

    Insulated wire. Springs are spaced apart. I'll post a picture soon.
     
  17. Anonymous321

    Anonymous321 New Member

    Joined:
    May 2, 2008
    Messages:
    93
    Likes:
    0
    It's 7:58pm here as I post this. What is it in Hertfordshire? But I am about to have dinner. I'll just skip it though, so no worries.
     
  18. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    Its one in the morning here,
    you bought a camera just for this ?

    Maybe you were getting one anyway.
    Hope it wasn't too expensive.

    Anyway, i would like to see this spring arrangement ..

    John :)
     
  19. john1

    john1 Active Member

    Joined:
    Jan 26, 2003
    Messages:
    1,295
    Likes:
    6
    Location:
    RW
    No, dont skip dinner.
    you might fade away ...
     
  20. Torben

    Torben Well-Known Member

    Joined:
    Oct 6, 2006
    Messages:
    2,507
    Likes:
    34
    Location:
    B.C., Canada
    Sounds like it should do the trick. Same idea as the 30-in-1 or 100-in-1 electronic lab kits sold by Radio Shack back in the day.

    OK, here's a basic circuit. It's essentially the same thing that Hans (AKA Boncuk) posted earlier, except this one uses a Darlington pair instead of just one transistor.

    I've drawn this one running from 9V, on the hypothesis that you have a 9V battery and not a 12V battery handy. You can either replace R3 and the LED in my circuit with your buzzer (make sure the + lead goes to V+ and the - lead goes to the collector of the Darlington pair) or just wire it parallel to LED/R3 so that you get light and sound when the beam is broken.

    The buzzer should work fine at 9V; just won't be as loud as at 12V. If you want to run the thing at 12V just increase R3 to 680 ohms or so first to protect the LED. (Hm. You don't list 680 ohms in your parts list--so if you run it at 12V, try 1K for R3 and if that's too dim use 330 ohms in series with 470 ohms instead).

    When I built this last night it would make a godawful howl unless I kept my cheap laser pointer aimed right at the LDR.

    If you have any questions or problems lemme know. This should take about 5-10 minutes to wire together and test using your spring board.

    I assume you have an LDR and a laser pointer or similar? Your original post mentioned something about running a laser on 28.5V or so. . .? Cheap laser pointers often just run off of 3 1.5V button cells in series. What kind of laser are you using?


    Good luck!

    Torben
     

    Attached Files:

  21. audioguru

    audioguru Well-Known Member Most Helpful Member

    Joined:
    Mar 16, 2004
    Messages:
    32,573
    Likes:
    950
    Location:
    Canada, of course!
    ONLINE
    I hate seeing circuits with the batteries connected backwards.
    EDIT:
    I missed the last 3 pages of this thread.
     
    Last edited: May 5, 2008

Share This Page