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rc car controled by the boe bot — Parallax Forums

rc car controled by the boe bot

andy11667andy11667 Posts: 26
edited 2005-07-19 03:48 in Robotics
i hove a traxxas rustler controled by a boe bot but im having some problems with parts of the car heating up and smelling bad can somebody help me

ps the car is electric and the speed control is a servo

Comments

  • steve_bsteve_b Posts: 1,563
    edited 2005-07-13 11:08
    What parts are heating up?
    Motors/Servo's??
    Or other parts like the battery's?

    Just a tip....mellow out the font, you don't need to type huge to get ppl's attention!! [noparse];)[/noparse]

    And the "PROJECTS" forum is more for finished projects as opposed to problems.

    See if you can move this to the Sandbox or Basic Stamp forum!

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    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • andy11667andy11667 Posts: 26
    edited 2005-07-13 15:40
    the arrow points to the part that heats up
    352 x 288 - 53K
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 15:47
    Its hard to understand what the device in your picture is, do you know? Can you tell us where the wires it is connected to go (motor, stamp, etc)? It looks like it maybe the motor controller, but its hard to tell from the picture.

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  • andy11667andy11667 Posts: 26
    edited 2005-07-13 15:58
    it is connected to the speed controler servo
  • steve_bsteve_b Posts: 1,563
    edited 2005-07-13 17:59
    Hmmm....does this heat up after prolonged use? Does it heat up on powerup?
    How hot is hot!? (sounds dumb...but everything heats up as it's used!).

    What voltage does it require? and how much are you pumping in to it?
    Maybe your wheels are too big for the servo's....requiring them to draw more current in order to turn big meats like those....

    The more you give us...the more we can give you back!

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • Steve JoblinSteve Joblin Posts: 784
    edited 2005-07-13 18:17
    I have built a few RC cars a while back... If I remember,they used a ceramic resistor to reduce the flow of electricity to the motor as a way to change the speed.· I remember that they usually had a metal "cage" around them because they got so hot.· I wonder if that is what are pointing to in your picture.· If so, it may be "normal" for it to get hot.
  • andy11667andy11667 Posts: 26
    edited 2005-07-13 18:56
    that is what im pointing to but it never got that hot (3rd degree burn hot)
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 19:00
    I am still trying to grasp exactly what this device that is heat up is, you state that the device is connected to the speed controller, Traxxas describes the speed controller as a "precise rotary mechanical speed control", there is a noticble absence of other manufacturers using any similar technique except in this link.·I am guessing it is a potentiometer which is coupled to a servo? The device that is heating up is only connected to the speed controller? There·is absolutely nothing else connected to the module which is heating up? (Like say your motor?) It is really hard to say what is causing the module to heat up if you don't know what it does to begin with.

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 19:03
    That big copper colored cable connected to the motor, is that also connected to the module heating up? If so that module is your power control module for your motors, they should be heating up, you should only become concerned if you get a blister from touching it.

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  • andy11667andy11667 Posts: 26
    edited 2005-07-13 19:05
    no it only heats up when i connect the board of education
  • andy11667andy11667 Posts: 26
    edited 2005-07-13 19:05
    im just woried about a fire or damage to the car or the board
  • andy11667andy11667 Posts: 26
    edited 2005-07-13 19:07
    it is a ceramic resistor to reduce the flow of electricity to the motor as a way to change the speed. I remember that they usually had a metal "cage" around them (steve joblin)
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 19:11
    I assume by quoting Steve that you are confirming this is what the module does. Since the resistor has a metal cage around it, it is clear that the designers knew that this part would give off excess heat, the cage is there to prevent you or a cable from coming in contact with it and burning. You shouldn't be concerned about the heat issues other than keeping electrical wires from resting on the cage, if the resistor is indeed ceramic it will stay intact even up to temperatures get hot enough to melt metal, just dont cause any strong temperature differentials on the resistor, such as pouring cold water on it, that will cause it to crack.

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    Post Edited (Paul Baker) : 7/13/2005 7:17:18 PM GMT
  • andy11667andy11667 Posts: 26
    edited 2005-07-13 19:15
    yes but it never got that hot
  • andy11667andy11667 Posts: 26
    edited 2005-07-13 19:16
    im just worried about damage to the car and board
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 19:20
    Dont worry about it, the metal contacts on the resistor will melt before the ceramic is damaged. Just dont pour cold liquids on it, that will crack it. Those motors are heavy duty, they likely require alot of current to run. this will cause the resistor to heat up significantly, this is why the designers chose a ceramic resistor. Just keep all wires and loose objects from resting on the cage.

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 19:22
    If you are concerned about damage to your stamp place a 220 Ω resistor between each of the output pins and the device they are connected to, the rest of the truck should have been designed to handle the heat from the resistor.

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 19:26
    I just re-read the post, the "smelling bad" is actually an ominous sign. So forget my advice about "don't worry about it". Smoke and/or acrid smell is a bad sign. Im stepping out of this thread because I feel I can't really help you any further without getting my hands on your truck.

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  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 21:21
    Steve you seem better equiped to help him.

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  • steve_bsteve_b Posts: 1,563
    edited 2005-07-13 21:26
    I assume you mean Steve Joblin! tongue.gif

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-13 21:28
    heheh, yeah sorry, I just scrolled back to his post, I forgot you responded as well.smile.gif
  • andy11667andy11667 Posts: 26
    edited 2005-07-14 01:44
    thanks for all your help
    ill just switch to a cheaper car
  • Steve JoblinSteve Joblin Posts: 784
    edited 2005-07-14 14:18
    The ceramic resistor should be hot when used, and may give off a slight odor when new.· Make sure all wires and anything else that is flamable is as far away from the resistor as possible.· I am not quite sure what your design is, but I wonder if you should be replacing the speed controller/resistor with a better electronic unit that works on PWM rather than slowing a motor by resisting the flow of power.
  • steve_bsteve_b Posts: 1,563
    edited 2005-07-14 15:07
    also note that if your car sits about, when you finally start it up, the dust will give off a bit of an odour too!

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    ·

    Steve

    "Inside each and every one of us is our one, true authentic swing. Something we was born with. Something that's ours and ours alone. Something that can't be learned... something that's got to be remembered."
  • DiablodeMorteDiablodeMorte Posts: 238
    edited 2005-07-18 14:25
    Hello, I realize this tread may be alittle old. But. Anywho. This "smelling bad" sign may not be good. As the guy above me said it may just be from the dust or it may be serious. I know that the last time my RC Traxxas Card "smelled bad" I had cause a transistor inside it to explode which cause it to complety nukify(ie brun to a crisp) all parts around the transistor. IF you could maybe get me a better picture and/or a schematic of the setup that would be nice
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-07-18 15:43
    Yes I think posting a schematic of how you have interfaced with the car is nessesary to further diagnose·your problem. I know you are presently looking for alternatives to the servo/ceramic resistor motor control, but if your fundamental connections from the BS to the car are wrong, there is a chance you'll have problems regardless of your motor control method.
  • DiablodeMorteDiablodeMorte Posts: 238
    edited 2005-07-19 03:48
    oh, And Just to show that i am qualified for Traxxas-Basic Stamp Interaction :P I'll post a few pics of what i did:

    Picture010.jpg

    Picture009.jpg

    Picture011.jpg

    And yes it does move. If y'all want it i'll post a movie
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