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Radio-controlled devices

Discussion in 'Safety' started by jwl868, Dec 18, 2008.

  1. jwl868

    jwl868 Active Member

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    Location:
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    Does anyone know what signals or devices can activate radio-controlled toys?

    For the studio’s production of The Nutcracker, we use a couple of radio-controlled devices for a couple effects. These are off-the-store-shelf “toy” remote control units. (One is remote control mouse. The other is a remote control car that is used to speed the hands of a prop grandfather clock.) The clock has been used for years, but this was the first time for the mouse. [Turns out they run on the same frequency, either 25 or 27 MHz, but that wasn’t the problem.]

    Just prior to and during the first show, something activated both units. Not just once, but many times and often for a few seconds each time. (I had noticed the mouse running before the show started, so it was safely on its back. The clock moved early and I had to slip on stage during a dark scene and reset it.) The stray signals occurred only a couple times during the second show. But there were no stray signals during the dress rehearsal, and as far as I can remember, never in the years before.

    This was a new venue for us. The venue is a separate building, though it is connected by passageways to other classroom buildings. We were the only group in the venue building. It was a Saturday, so there were few people on the campus.


    Joe
     
  2. TheSwami

    TheSwami Member

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    Location:
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    Most off the shelf radio-controlled devices operate around the 27 MHz (26.96-27.54MHz) or 49 MHz ( 49-49.6 MHz); the toy should specify which on the product itself. Some modern RC cars have a small switch on the transmitter and receiver to switch between the two, so that two of the same model car can operate in proximity (one on each band).

    There 10-meter and 6-meter amateur radio bands range from 28-29.7 MHz and 50-54MHz, respectively. It's possibly that a nearby ham is operating improperly or at high power, causing interference on your system. If you manage to identify and contact the source, he or she is required to take action to avoid interference with other electric or electronic equipment.

    Other than that, any computer/antenna/wiring could be giving off stray signals that the RC units could be picking up. There isn't a whole lot you can do, other than upgrading the RF systems themselves. You might try finding a PCM transmitter/reciever (pulse coded modulation) instead of the typical FM, as these typically have fewer problems with interference. Also, finding a RC car that operates at 72 or 75 MHz can help, as there are fewer consumer electronic devices that specifically transmit on those frequencies.

    Best of Luck!

    73
     
  3. RGJones

    RGJones Member

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    Hello,

    Not trying to be a pain, but as a ham radio operator myself, i would like to provide some insight. If it is a ham operator causing your interference then they could be a major help to you. Although they are not required to help, or stop their interference (we have priority on most bands), most hams are very very helpful, and will be glad to help in any way they can. Even if that means going above and beyond and helping you solve your problems even if it is not the ham operator. Also check the ARRL website, they are the main amature radio organization and they are very helpful. There is much information on the site about interference and how to fix it.

    I myself would be helping in any way I could, especially since I also do theater and I know how much a pain this must be.

    Hopefully I can be of help. Again I am in no way trying to cause a stir.

    Rob
     
  4. TheSwami

    TheSwami Member

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    No worries RG, you're always welcome to voice your concerns and help. As it turns out, I was misremembering the FCC guidelines on interference. As a ham myself, I had always thought we were required to solve our own interference problems. And while it turns out that that's not quite the case, you're definitely right in saying that hams on the whole are very helpful in solving problems in going above and beyond to help out others. So while I was wrong in saying that, if it was a ham, he'd be required to solve the problem, I'd eat my hat if he wasn't at least willing to help. Thanks for the correction RG. :)

    73
     
  5. Van

    Van CBMod CB Mods Premium Member

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    As Someone who has cobbled together many a stage trick with "off the shelf" R/C stuff, I'm sorry to say that this is a problem you may not be able to correct. Using a PWM R/C or other digitally regulated signal may be your only answer. Unfortunately there are so many potential interference sources; Hams, CBer's operating on "the Funnies", Harmonics from other "legitamate" sources, you might never be able to identify the source. Fortunately, for you, non of these effects are Life/Safety issues, but as a way informing youngsters I think this is an excellent oppurtunity to bring up the point that R/C control for things like revolves, flying systems, any type of pyro or other effect must be handled with an eye towards worst case scenerio.
    You can obtain a relatively cheap solution for your clock by scrounging the innards of a garage door opener. Using the transmitter and receiver from that will at least allow you to set the "security" code so that only that remote, or one set to exactly the same security code will operate the clock. For the mouse, your best bet is to obtain a "real" R/C setup from a hobby shop < yes the big expensive kind> as those frequencies are much less prone to interference.
     
  6. Anonymous067

    Anonymous067 BANNED USER

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    Too bad the same can't be said for me in other forums in this site.
     
  7. Anonymous067

    Anonymous067 BANNED USER

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    An RC controlled revolve? I'd laugh my ass off if I saw a kid in the audience with a remote control car.....
     
  8. RGJones

    RGJones Member

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    Location:
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    Thanks Swami! Its nice to know theres a place i can be welcome, and its nice to meet other hams. I completely missed your 73 when i posted, thats a dead giveaway. Anyway, i hope this problem gets worked out, whatever the cause.

    Rob
     

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