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Inexpensive transmitter and receiver?

Discussion in 'Electronic Basics' started by David, Jan 12, 2008.

  1. David

    David Guest

    I need an inexpensive receiver to hook up to a high intensity speaker (I'm
    thinking a smoke alarm speaker). I'm going to place it in another device
    (dvd player maybe) and mail it to myself in an attempt to figure out what
    unit in my apartment building is stealing my packages (the common area is
    locked and this has happened a few times now, once within hours of drop
    off).

    Can anyone recommend a receiver that will run for a week or so without
    draining its batteries?

    I'm thinking about just picking up an inexpensive R/C toy and pulling the
    receiver out of that but I need at least a few rooms worth of range and I am
    unsure how much power the receiver itself requires. Anyone know?

    Thanks,

    Dave
     
  2. Chuck

    Chuck Guest

    Interesting, Dave.

    You could also plant a transmitter into the device and use crude
    direction finding techniques to locate it. It could be powered by the
    DVD power supply, or by its own battery.

    To increase battery life, key the transmitter with a timer so it is on
    only a few minutes each hour. Battery should last a long time.

    Chuck
     
  3. Bob Monsen

    Bob Monsen Guest

    They sell direction finders for finding lost model airplanes. The
    transmitter is very light, and they are cheap. search the web for 'rc
    airplane locator'.

    The other possibility would be to put an airhorn in the package, triggered
    to go off when it is opened. That would wake up the entire building. If you
    rigged it properly, s/he wouldn't be able to quiet it for a few minutes.
    Maybe the painfully loud noise would be enough punishment to make them stop.

    However, suppose you figure out who is doing it. What then? The cops won't
    take your word for it and arrest the creep. You can't break into their
    apartment. You could confront them, but that might lead to violence.
    Instead, why not use general delivery?

    Regards,
    Bob Monsen
     
  4. David

    David Guest

    Hi Chuck,

    I wouldn't know exactly how to proceed with the direction finding- I'm
    hoping for a rather simple solution. Plus there's no gurantee that they'll
    be plugging the DVD player in.

    I like the timer idea if a typical receiver would drain its batteries in
    less than a week but otherwise I would like the option to turn on the buzzer
    at any time.

    I suppose I could pulse the transmitter once a minute and then latch the
    buzzer on after a signal is received but my goal is to keep everything as
    simple as possible. The less I need to order the better, since my orders
    are being stolen in the first place, LOL.

    Dave
     
  5. terryS

    terryS Guest

    Suggestion: A battery operated baby monitor; mail the transmitter
    switched on with extra battery/batteries hooked up for longer life.
    The receiver could be mains powered and left on all the time in your
    apartment until you hear the package being opened.
    I bought one recently for $20 and presently use it to transmit a house
    alarm across the street to a neighbours when I'm not home.
     
  6. David

    David Guest

    Bob, I love the air-horn idea. Won't be quite as simple to set up, but I
    love the idea.

    I don't expect the police to arrest the person based on my word but I plan
    to call to file a report on the previous mail loses the day the package goes
    missing. At that point I will tell the officer what I did and if s/he isn't
    interested in pursuing it further, that's their choice. I expect they would
    be willing to knock on the creep's door. The creep would be confused and
    flustered and if the police are excellent at intimidating- if they asked
    what the noise was and if they could come in and take a look around, they'd
    be busted. A few years ago when I had a problem with a neighbor the police
    were happy to go knocking on doors, I don't see why they would respond
    differently in this case. I believe it is the same neighbor but I would
    like to be certain before throwing accusations around.
     
  7. default

    default Guest

    Or just a cmos long delay counter and timer to sound the alarm after a
    predetermined time.

    Awhile back I looked into using a timer counter to check the time
    between maintenance intervals on some equipment - using a large cap to
    keep it happy when it was unplugged. Ultra low current drain - months
    on a few AA batteries - and maybe a separate alarm battery?

    You have another option - put the transmitter in the DVD player and
    have it send out a chirp when the DVD is plugged in, or taken from the
    box - assuming the thief will use the player himself . . .
    --
     
  8. John Larkin

    John Larkin Guest

    How about some really serious red dye?

    John
     
  9. David

    David Guest

    There are a lot of good and creative ideas but I want a solution that will:

    - not destroy someone else's property
    - function "on demand," regardless of if the dvd player has been plugged in
    or removed from the box
    - will clearly identify which apartment unit the dvd player is in

    I always like hearing more ideas but aside from battery life and transmitter
    range, what are the downsides to the r/c buzzer idea? I will ensure the
    transmitter range is sufficient but the battery life is the one variable I
    have to investigate more.

    David
     
  10. Vince Morgan

    Vince Morgan Guest

    That puts my plastic explosive idea to rest I guess.
     
  11. Sparkfish1

    Sparkfish1 Guest

    Why not just run a webcam from your door to see wh is doing it and
    then you have proof to go to the police


    I recently bought a web cam ( labtech) for about ^gbp and it has a
    motion detector that runs a video recording only when movement is
    detected OR it can be set to record everything over a set period of
    time

    It is quite small and , above eye level it would not be noticed

    I admit you would have to have some sort of extension lead but I would
    have thought that woudld be easy to do
     
  12. Sparkfish1

    Sparkfish1 Guest

    HOW ABOUT AN old mobile phone ?
    coupled to your speaker alarm
     
  13. gearhead

    gearhead Guest

    Why do the responses to your post mention "the police" instead of
    postal inspectors? Postal insprctors have the power to make arrests,
    you know.
    Someone has stolen your mail (a federal offense), and you should
    contact the post office immediately if not sooner, as the saying goes.
     
  14. Nemo

    Nemo Guest

    As a backup idea...

    in case the other ideas fail, wrap the DVD player in very bright,
    noticeable gift wrap paper and check the trash after it's been stolen.
    It should be mixed in with the culprit's trash. It's not legal proof,
    and if the guy's bright he'll put it in someone else's trash, but it'll
    help *you* zero in on the perp.

    The mail service may take exception to posting anything dodgy through it
    (like active radio transmitters or chemical dye bombs) so, have you
    considered faking a box that has gone through the mail and putting it
    there yourself, maybe re-using an old box with stamps etc on it. Would
    be cheaper too!

    The police probably won't accept any evidence except video surveillance.
     
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