Amplifying using tip31.

Discussion in 'The Projects Forum' started by ygobi, Jan 14, 2012.

  1. ygobi

    Thread Starter New Member

    Jan 14, 2012
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    Hi, I'm taking parts from an old toy RC helicopter and turning it into an little car which can't turn. I want to use the tail fan as a turbo/air brake thing using the right gyro stick on the controller. I cut the power leads for the fan and replaced it with another powerful and bigger fan to see it it will work. Then I took a tip31 , attached the power leads coming from the heli board and attached the positive on the right leg and negative on the left (It might be opposite :$). I took the negative from a 9V battery and hooked it up to the negative part of the tail fan power lead. I attached the middle leg from the tip31 and attached it to the motor and attached the positive from the 9V battery to the new motor. I tested it and it only worked as turbo, no brakes :(. (I think you get what i'm trying to do here. Amplify the tail fan power leads to be compatible with the new motor.). I forgot about the reverse. Anyone got ideas? I have 6 tip31's in my box and I will use them if I have to :).
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
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    Did your dog eat your schematic?

    We really need somewhere to start.

    Show us in schematic form how it was originally wired, and then what you tried which did not work.

    Without a schematic, the process will take far longer, and will be much more prone to errors. Besides, you won't know how you got from one state to another.
     
    DerStrom8 likes this.
  3. ygobi

    Thread Starter New Member

    Jan 14, 2012
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    I'm 13, I really don't have time to make some advanced schematic and I don't even know anything about the board that's controlling this. On the controller if you push a stick up the car will move forward faster and if you push down the car goes slower. I want to amplify that line where it makes the car faster and slower. I hooked it up to a tip31 and with a 9V battery but it can only go forward and cannot go backwards because the transistor cannot accept reversed polarity.
     
  4. PaulEE

    Member

    Dec 23, 2011
    423
    32
    So, you've got the TIP31, two biasing resistors, an emitter and collector resistor, and maybe a filter or bypass cap somewhere...maybe. That's what, six components? That's six different components and positions; 6! = 720 right and wrong combinations - and we haven't gotten to the actual RC car yet - nor do we know whether this TIP31 scheme will do any good for you.

    RC cars work by on/off signals triggering motor drive circuits. How they do this depends on what car/truck/helicopter/boat you have, who made it, and how good a device it is.

    I assume that you want to beef up the power to the motor so you can drive this thing through more aggressive terrain than a tile floor.

    This implies testing the current circuit. Where is the control signal? What does it look like? What circuit does it drive?

    An ideal (educated guess) circuit for you would probably be an H-bridge and beefier batteries.

    The H-bridge is a subject within itself and beefier batteries imply higher voltages and currents everywhere else - which you'd have to be sure are compatible with the control circuitry, or you'll blow the thing up.

    We need more info, bud. Can you find your device on the internet? Maybe someone has hacked a schematic together to take a few guesses with.
     
    Last edited: Jan 16, 2012
  5. ygobi

    Thread Starter New Member

    Jan 14, 2012
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    0
    Well, all I did was take the R/C helicopter apart, took 2 motors from it, attached a wheel on those motors, made a frame, glued a motor holder, placed the 2 motors, took out the board, taped it to the frame, cut off the tail motor, attached the tail motor power leads to a high power motor, put 2 more wheels on the back of the frame and their you go. All i want to do is amplify the tail motor power leads so the now high power motor could have more power. I've tried with one TIP31 and it works but when i reverse the original tail motor power lead polarity the motor stops working. What can I do to make the motor work on both polarity with the transistor.
     
  6. PaulEE

    Member

    Dec 23, 2011
    423
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    On the original helicopter, what did the "tail motor" lead do? From what I can tell, it simply ran a motor on the back end of the helicopter. Was this motor able to spin both clockwise as well as counter-clockwise? Was it able to be off?

    I need to understand what sort of signals this lead uses to make the motor do what it does. From there, I can suggest a boost circuit (as well as everyone else).
     
  7. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    We're not asking for "some advanced schematic". We're only looking for a basic design of what you're trying to do. If you don't have time to give us the information we need to help you, then I guess we don't "have the time" to help you. Any diagram of what you're trying to do would help here.

    In your description, you said you connected the "power wires" to the opposite pins of the TIP31. If I'm understanding you correctly (this is where a diagram would come in handy), you're connecting it completely wrong. However, since you refuse to post a schematic, I'm not entirely sure.

    Regards
     
    spider87 likes this.
  8. ygobi

    Thread Starter New Member

    Jan 14, 2012
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    Those power leads is just a basic DC signal. When the helicopter was assembled, the tail motor would spin clockwise when the controller stick faces up and would spin counter-clockwise when the stick faces down. How can I amplify this DC signal with both polaritys so the new motor can also spin both ways on the R/C car i'm making?
     
  9. DerStrom8

    Well-Known Member

    Feb 20, 2011
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    To be honest, that really isn't any help whatsoever. We really need a simple diagram of what you're doing (doesn't have to be a schematic, necessarily), even if it's just a basic drawing of the setup. If you refuse to give us that, then I don't see how we can help you further.

    Remember, weak questions get weak answers. If you aren't happy about the answers you're getting, it should tell you something about the questions you are asking.
     
    spider87 likes this.
  10. PaulEE

    Member

    Dec 23, 2011
    423
    32
    If you're able to spin the motor one way or the other by toggling the remote, one option would be to do the following.

    Instead of a motor, hook up a resistor. Say, 10,000 ohm or so. We can use this as our new circuit's control signal.

    Depending upon what voltage results across the resistor, we might need to level-shift it. With one meter lead connected to one side of the resistor and the other meter lead connected to the remaining side, you'll probably get +/- some voltage. Let us know what that voltage ends up being to continue the motor buffer design.
     
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