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Remote operated security gate lets you phone it in

ring_detection_circuit

[Itay] has a friend who works in a rented office where the parking lot is secured by a remote-controlled gate. Unfortunately, while his friend shares an office with several people, they only received a single remote. To help his friends out, he built a small device that triggers the remote control whenever a phone call is received.

The remote modification was rather straightforward. He simply opened the device, adding a single wire to each button terminal. Rather than connect to the remote using wires, he decided to fit it with what looks like a scavenged DC power jack. The ring detector circuitry was constructed and stuffed in a small phone box, which is connected to the remote using a DC power plug. It’s a great solution to the problem, but let’s just hope no one gets a hold of the phone number they used for the trigger!

There are plenty of pictures on his site, as well as video of the ring detector being tested. Unfortunately [Itay] lost the original schematics for the circuit, so you will have to flesh that part out on your own if you wish to build a similar device.

Keep reading to see a few videos of the remote in testing and in use.

Comments

  1. Dangger says:

    So they have to pay for a dedicated phone for this hack? It cost $35 buck in our area just to have a land line active. Courtesy calls would be a problem.

    I wonder if they could’ve bought those universal garage door openers or the likes and just ‘learn’ transmitted signal to them. Or wireless remote light switches, wireless door bells. If range is a problem there are Spread Spectrum transceivers. Even an answering machine device that allows you to hit # and enter a pin to activate a signal.

    Thumbs up for effort, even if it doesn’t sound reasonably logical.

  2. itay says:

    dangger: it was connected to a fax line which was rarely used. this was done as a favor to a friend, quite a silly circuit actually, but served its purpose very well.

  3. CH says:

    I would have thought it easier to connect it to a computer (easier if there is a free parallel or serial port)?

  4. Lt bob says:

    I wonder if you can put like some lan line or something like italkbb which uses internet to make a phone line.. hookup a answering system and set up a password just for the extra security

  5. jeditalian says:

    lol. “[Itay] has a friend who works in a rented office where the parking lot is secured by a remote-controlled gate. ”
    no longer secured. now, stop renting, return the remote, and swing by whenever you want.
    now you can be their handyman and come fix that problem where everytime someone calls the fax line the gate opens :P

  6. Grayda says:

    How easy would it have been to answer the phone, but wait for a keycode before opening? That would solve your security issue there. All you’d need to do is build in a way to listen for the right code.

    Not being an electronics man myself, I’m not sure how easy that is, though..

  7. Frogz says:

    could always buy a pay as you go cell phone(t mobile is $10 per YEAR to keep the number)
    and as long as it didnt pick up, it would retain any minutes on it
    $10 per year for gate usage isnt bad at all

  8. oneshot719 says:

    why not use tropo.com and free phone number, integrate it with the API and run it on your local system, serial port to control the lock, all free and in the cloud.

  9. a_do_z says:

    Might the security be addressed sufficiently by using CallerID? A quick search turns up a number of microcontroller based CallerID circuits.

  10. biozz says:

    1) if it fails your screwed
    2) i think HaD already posted this

  11. itay says:

    grayda: more complicated, as it will require an mcu. here i used only a 555 and an optocoupler. no programming.

  12. SparkyGSX says:

    I wonder if the other residents and the landlord know about this security-by-obscurity gate opening device. If something ever happens in that parking lot, the insurance company might refuse to pay if they found out, and Itay and his friend might be liable.

    Not only would a cellphone be cheaper, it would also allow you to do caller screening, which would make it at least somewhat secure.

  13. Jim says:

    It should be possible without MCU to trigger the remote only if the phone rings 3 times then hangs up. This would filter out cold callers and wrong numbers who would typically keep it ringing for longer…

    That said, I suspect Itay already considered many of these constructive points.

    Known limitations, acceptable imperfections, for the operation and presentation are part of the charm of hacking. Hacks are often for a very personal set of requirements, cost and even skill set restrictions, rather than as a prototype for a commercial product!

  14. itay says:

    jim, thanks for the insightful comment. at the beginning i did want to do it with an mcu and various tricks, but the “clients” insisted it’ll be as simple as possible and said it’s enough. as said before, this gizmo proved very useful.

  15. Just make sure the phone number is on the Do-Not-Call list!

  16. Dangger says:

    Frogz: That is the best idea I’ve heard yet. I have never thought of using those pay as you go phone for hacks. I need to start brain storming! =]

  17. Ekaj says:

    Yeah, security fail. This number will be called by someone other than the employees, and the gate will open.

  18. Geter_Priffen says:

    Heh, I have to laugh at everyone screaming about security this, fail that. Did you even watch the video on the guy’s web site? The lot is “secured” by a simple arm that blocks the path of a car, much like you see in toll booths. It’s not as if this place is locked down like Fort Knox – the only requirement for entrance is the ability to duck!

  19. cpmike says:

    looks like a DSL line filter was used for the case.

  20. John Mac says:

    Awesome! this is so freakin cool. My apt comples at my university has a gate phone similar to this one, i’m so stoked to try this out for my buddies! You need a donate button good sir

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