RC Signal strength is weak..need solutions!

Discussion in 'Wireless & RF Design' started by tubachris85x, Feb 12, 2014.

  1. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1
    I really appreciated the help given to my on the other side of the forums for a basic servo project I've been working on, but this next issue is something I think is better suited here (I'm quite an amateur at these subject, so please, forgive me!)

    To the topic...

    I put together a mash up between a small servo and a scrapped RC toy car transmitter/receiver, so I can operate it wirelessly. Connections all work and it operates as far as function is concerned.

    My issue, is that the signal strength is considerably weak. I literally have to be within a few inches of the receiver's antenna wire for me to get it to operate. When the signal is close but not close enough, the servo will not operate smoothly

    I gutted the transmitter (RC controller) and simply removed the telescoping/non-wire antenna, but the wire that ran from it to the circuit board remains exactly how it was when I took it apart. Same for the receiver antenna wire, which is significantly longer.

    So, is there a way to fix this issue? It is not power, as I've swapped out new and old batteries during my tests. Fixing this will pretty much make or break the servo aspect of this project, so I am really in need of assistance from experts on the matter..

    Thank you for your time!

    -TC
     
  2. PRFGADGET

    Active Member

    Aug 8, 2011
    50
    7
    "I gutted the transmitter (RC controller) and simply removed the telescoping/non-wire antenna, but the wire that ran from it to the circuit board remains exactly how it was when I took it apart"
    Re connect the telescoping antenna or at least an equivalent length of wire to the transmitter, it was there for a reason !
    If you can measure the operating frequency of the transmitter , you might be able to build an "electrically equivalent" but physically shorter antenna which might serve your purpose.
    Keep in mind that shortened antennas are more critical about their tuning and as with any antenna they are effected by thing's around them and can "DE-TUNE" easily.
     
  3. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1

    I'll give this a shot. Given the application, I've been trying to avoid using the telescoping antenna.

    When you say building a "electrically equivalent but physically shorter antenna," how would I go about this method? I can get the frequency on the to car (can't remember off the top of my head)
     
  4. PRFGADGET

    Active Member

    Aug 8, 2011
    50
    7
    Not knowing what FREQUENCY the system is working at.
    The best example I can give you is to look at "CB" antennas, a 1/4 wave "FULL SIZE" cb antenna is 102 inches long.
    Then there are "LOADED" antennas that are physically shorter than a quarter wave but electrically are 1/2 wave or 5/8 wave but only around 48 or so inches long (some even shorter).
    You need first to determine the operating frequency of the transmitter , then do some research into antenna design ( take a look at ac6v.com).
     
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  5. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1

    Oh ok, I understand what you mean now.

    I'll get back to this when I get back home from work. I'll see what I can do.

    I have been getting mixed responses from others as well, saying that increasing the antenna length won't necessarily mean it will be stronger, and others have said (in reference to increasing antenna's length) that the signal will actually become weaker. And another mentioned an antenna "ground" wire as well!

    The application for this is for a replica costume, where the servo/receiver is placed inside of a mask, and the controller/transmitter is located inside of a sleeve/glove (hidden from view). As for operating the transmitter, the buttons are extended to the palm...think classic comic style spiderman webshooters, and that's how I designed it.

    So the signal needs to realistically only travel at least 2-3 feet.

    Thank you for your help and patience..!

    -TC
     
  6. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    use a piece of flexable wire the same length as the telescoping antenna was, that should work. and most toy rc stuff is on 49 mhz.
     
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  7. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1
    This entire costume project has much left to do, so it'll be interesting to do the testing on this between the sculpting and the molding....blah....
     
  8. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1
    I certainly hope this is a viable solution, as some of the other ones involve modifying the circuit board..I've already encased both transmitter and receiver boards in hot glue for protection...
     
  9. PRFGADGET

    Active Member

    Aug 8, 2011
    50
    7
    Depending on where you WANT to run the antenna wire ( I am going to assume you might run it up the sleeve from the glove ) you might want to make the wire just a bit longer ( your body will absorb some of the RF from the transmitter ) than the original antenna.
    You will also want a insulated "quick connector" of some sort for the glove to sleeve thing.
    Now that we have a better idea of what you are trying to accomplish we can be of a bit more help (maybe).
    Your RC transmitter is LOW power (as in millawatts) so you need to get as much of that as possable in the air as you can.
    You haven't said much about the receiver so I am guessing that you did not shorten that antenna as well.
    They both need to be kept as close as possible to the original length in order to work.
     
  10. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1

    Thank you!

    Here's a better breakdown of how I am using this whole thing:

    The sleeve is an arm-glove (it's all one piece), it's not a full on sleeve, as there will be open skin between the glove/sleeve and then the upper arm. If I had a full sleeve, I would have just said "screw it" and hard wired the antennas to each other.

    As for the RC car's frequency, it's 27.145 MHZs, just checked.

    For the receiver, yes, I simply detached it as it was internally wrapped around the outer edge of the toy car chassis.

    The glove itself is of a thin, flame-retarded material FYI. I'll post pics of the devices shortly
     
  11. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1
    Just some quick pics from when I first got things wired:

    Servo w/ power supply, and receiver board (I covered it in hot glue as you can see). The long black wire to the left w/ the white heat shrink is the antenna wire. I've since removed the outer protective wire material on the tip to expose the copper wire.

    [​IMG]

    Transmitter/controller board. Please forgive the rough appearance of it.

    [​IMG]

    other side (before coating it with hot glue)

    [​IMG]


    The white wire you see there is the antenna, again, as with the black wire on the receiver, I removed the tip of the protective wire coating.
     
    Last edited: Feb 13, 2014
  12. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1
    pics resized....
     
  13. PRFGADGET

    Active Member

    Aug 8, 2011
    50
    7
    If you can run a small wire from the transmitter antenna up one side of the "sleeve" and down the other ( folded dipole, sort of),you stand a fair chance.
    As to the mask, I would suggest hiding a wire from the receiver antenna around the outside edge of the mask if at all possible ( when it comes to low power, more antenna is your friend ) .
    "Radio Shaft" is your friend here, use "stranded" wire for "Flexibility" , last time I looked they had some #22 gauge insulated hook up wire (but don't hold me to that) .
    One other thought,,, BEWARE of HIGH POWER CB STATIONS near your operational area,,,you may get strange reactions from your mask ;-))) .
     
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  14. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1
    I'll give this a shot then. I've got a bunch of #22 gauge wire from there already.

    That was also my intent with the receiver wire in the mask! So I certainly hope this all works...thank you for your help!!
     
  15. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
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    post deleted
     
  16. tubachris85x

    Thread Starter Member

    Oct 25, 2013
    33
    1
    Alright, got it to work as needed...you were right, it was the need of adding a length of wire equal to the telescoping wire! Works way better then it ever has....thank you for your help!
     
  17. PRFGADGET

    Active Member

    Aug 8, 2011
    50
    7
    No need to thank me, you did the work !
    Trick was, to get you to realize that all transmitters and receivers need an antenna of some sort, the better the antenna ,,,,,the more efficient the system.
    If you are really interested in this sort of thing you might look into Amateur Radio, lot's of interesting thing's to do there.

    73 & have Fun !
     
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