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Speed trap DIY

Discussion in 'Electronic Design' started by Old Man, Aug 18, 2004.

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  1. Old Man

    Old Man Guest

    I live on a country type road with a posted limit of 40mph - and I enjoy
    evening walks. Problem is that some of the cars go far in excess of the
    posted speed, and it is quite terrifying to have to brave the slipstream of
    a car doing 80+.

    I want to build a simple (inexpensive) way to clock the speed of cars going
    past the front of my house. what i envisioned was a couple of light beams
    pointed at reflectors and a simple (basic stamp?) controller.

    off the top of my head it seems that I could canibilize an old remote
    control for led's and radio shack(or the ilk) to get the little receiver to
    "see" the transmitted beam. modulate the beam so the sun doesn't interfere
    and put a couple a know distance apart, run a cable up to the house and a
    computer or two...

    If i get it to work, a camera figures into the future plans. But first a
    BIG speed indicator would be nice to let them know that i really care....

    I really do not want to design build all this myself - i cant believe that
    someone hasnt published plans for something that i can adapt to my desires.
    A kit for the led/receiver would be stellar.

    Any Ideas?
  2. Joerg

    Joerg Guest

    Hi Old Man,

    Here is another idea: Get a good camera with software that detects
    objects coming into range, takes two pictures and measures progress
    between the two. This software ought to be standard by now. I don't know
    but I designed something like this about 20 years ago on a 68K
    processor. Then print out one shot, with the speed on there and the face
    of the driver, then for those where you can find out where they live
    send it to him/her. Now that'll embarrass folks.

    Regards, Joerg
  3. Si Ballenger

    Si Ballenger Guest

    A speed gun kit below that might be of interest.
  4. Rileyesi

    Rileyesi Guest

    I live on a country type road with a posted limit of 40mph - and I enjoy
    I don't know if the geometry of youru road will allow this, but...

    How about putting up two large markers (like two poles driven into the ground
    painted white) that are a known distance apart. Take a video of a car speeding
    and measure the time it takes for the car to travel between the poles. That
    will give you the car's speed. If possible, set it up to record the car's
    liscense plate. Show the tape to the cops. They might not be able to do
    anything with your tape, but it might convince them to put a speed trap up from
    time to time.

    Good luck.
  5. Fred Bloggs

    Fred Bloggs Guest

    Yeah- take a PIC and extract Doppler from digitized microphone input....
  6. Old Man

    Old Man Guest

  7. Wouldn't work in the UK - "Human Rights Act" does not look favourably on
    printing of pictures of offenders.

    Why not make up a speed readout on a pole outside your house. Use a Doppler
    radar module to find the speed. I wonder how long it would take for the
    police and local council to tell you to take it down?

    Graham Holloway.
  8. Richard

    Richard Guest

    Consider human behavior - this may actually encourage speeding. ("How
    high can I make it register?")

    Now, the radar gun idea is a good one. If they get conditioned to
    ignore their radar detector in your area, they'll get nailed the one
    time it's a real cop.
  9. nospam

    nospam Guest

    Campaign to have the speed limit increased then - that will solve the
  10. The police department here will lend (for free) a radar with a big
    electronic display board to homeowners who want to operate it on their
    property for a day or two. Maybe yours will too.

    Best regards,
    Spehro Pefhany
  11. logized

    logized Guest

    If you are in the UK,then you need to consider that any sign visible to a
    driver would be illegal and may get you into serious trouble if someone
    claims it caused an accident.
    Also, for the speeding driver to actually see the speed indicator, it would
    need to be some distance down the road which adds to the technical problems.
    Why not just stand near the road for a few hours, wearing a high visibility
    jacket and video any car you see speeding and give the tape to your local
    authority to justify some official speed measurements.

  12. Guest

    You could get some 2 foot long 2x4s, paint them to match the pavement,
    and place them at random positions at random times. At 40mph they are
    an annoying bump. At 80mph they get thown ou by the front wheel and hit
    the undercarriage of the car... For 25mph residential roads, use 4x4s.
  13. Wim Ton

    Wim Ton Guest

    If you are in the UK,then you need to consider that any sign visible to a
    In the UK speed cameras have to be painted bright red and yellow, as they
    only want to catch people who are speeding and not paying attention to the
    road. (Or the petrolheads have the majority in parliament ;-)
    I suppose an empy box of the right size and colours will do the trick

  14. Rich Grise

    Rich Grise Guest

    Set up a sawhorse with a cardboard sign: "Speed Trap Ahead."

    Good Luck!
  15. This kit is a piece of junk, don't buy it. Very limited in function,
    extremely short range, barely works, hard to calibrate. And it will not set
    off radar detectors because it is not in the X, K, or KA bands.

    You can get a used, commercial, police radar unit off of EPay. Simply look
    for "police radar". There are some deals to be had for some older X and
    early K band units. Most are calibrated and come with a certificate of
    calibration. Naturally, these puppies WILL set off radar detectors. Hunt
    around, some units have a "serial" port on them, which feeds readings to
    that port. From there you can feed to other devices (camera, computer,
    etc.) Once in a great while, a used speed display sign shows up.

    But stay away from the kit. junk.

  16. You'd be bending a few rules if you did this but:

    real Gunn diode cores:

    or theres this:

    10 Ghz and 24 Ghz are ham bands, right next to the radar bands, and
    the UK hams really belive in keeping their licensed spectrum clean, so
    you'd need to keep the power down to a milliwatt or two and use a no
    gain antenna, but for ~80$ US or so you have your own radar core right
    where the detectors are. The Ramsey unit has a very short range,
    maybe 20=50 feet, and its 1.2 Ghz, so it wont trip the radar detector,
    but a gunn module would.

    If you want a legal solution, aim a UK equvalent of a US part 15
    compliant license free microwave door opener module down the road and
    watch them hit the brakes. This might get you accused of jamming the
    cops,who have radar detector detectors.

    I too live on a back country road and understand :) It helps if
    its on some days and off others, they dont get used to it and ignore
    it. Just standing out in my yard and pointing the Ramsey kit about 10
    years ago caused people to totally STOP about three car lengths away
    from me,scared of the "cantenna" aimed at them.

    Steve Roberts
  17. Si Ballenger

    Si Ballenger Guest

    Other versions not much more than the kit, and probably actually
    work. A coffee can epoxied on the top of a plastic water gun and
    painted black (add a couple of wires too) would probably get the
    idea across if pointed at the traffic.
  18. Barry Lennox

    Barry Lennox Guest

    Do a Google search for "Trolling for tailights" Was a bit of an
    Internet classic in the early days. It's a real laugh, and it may give
    you a few ideas as well.

    Barry Lennox
  19. Any details, even a description, of how you did this would be welcome. I
    have a project in mind ( but not for vehicle speeds ) which could use
    processing like this.

    Reply to adrianjansen at internode dot net dot au


    Adrian Jansen
    J & K MicroSystems
    Microcomputer solutions for industrial control
  20. Tim Shoppa

    Tim Shoppa Guest

    A life-size cardboard cutout of a cop pointing a radar gun is much
    less techno but probably much more effective :).

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