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Author Topic: rc servo/gearmotor questions...  (Read 4283 times)

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Offline PrinceOfFlameTopic starter

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rc servo/gearmotor questions...
« on: May 01, 2007, 10:38:25 PM »
how would i connect a normal dc motor to a servo pin on an rc receiver? can i just connect the positive/negative wires to the red/black wires respectively, or would this not work? this is my first experience with servos, and any help is appreciated. Thanx in advance
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Offline nanob0t

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Re: rc servo/gearmotor questions...
« Reply #1 on: May 02, 2007, 04:12:23 AM »
If you're working with a servo there should be three wires.  The red/black wires are your power for the servo itself.  Then there should be a yellow or white wire, which is your signal wire.  This recieves pulses from a source and in turn it moves.

To connect the DC motor then, you want to avoid the signal pin, because all it does is recieve the commands.  You would connect the motor to the red/black pins.  Make sure the DC motor is capable of the power that it gives.

Offline dunk

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Re: rc servo/gearmotor questions...
« Reply #2 on: May 02, 2007, 04:30:40 AM »
Quote
To connect the DC motor then, you want to avoid the signal pin, because all it does is receive the commands.  You would connect the motor to the red/black pins.  Make sure the DC motor is capable of the power that it gives.
while nanob0t is correct, i'm not sure if that's what you meant.
that wouldn't give you any controll of the motor.
the motor would just turn continuously.
if you want to controll the motor using the R/C then you will need a motor controller.
try searching the R/C sites for a motor controller if this is what you want to do.

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Offline ed1380

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Re: rc servo/gearmotor questions...
« Reply #3 on: May 02, 2007, 05:25:00 AM »
I believe they're called ESC (electric speed controller) or electronic
« Last Edit: May 02, 2007, 05:25:43 AM by ed1380 »
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Offline hazzer123

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Re: rc servo/gearmotor questions...
« Reply #4 on: May 02, 2007, 09:37:30 AM »
Hmmm....

Couldn't you use the outputted PWM signal from the RC receiver to control the speed of the motor. Since it will output different duty cycles, won't this mean that the average power applied to the motor will be variable.

My idea for a circuit for this is connect the signal pin on the RC receiver to a NPN transistor. Then wire the collector and emitter to motor and the power source (all in series). You wont have direction control, but you will have speed control, though i dont know if the range will be large enough.
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Offline nanob0t

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Re: rc servo/gearmotor questions...
« Reply #5 on: May 02, 2007, 11:03:27 AM »
while nanob0t is correct, i'm not sure if that's what you meant.
that wouldn't give you any controll of the motor.
the motor would just turn continuously.
if you want to controll the motor using the R/C then you will need a motor controller.
try searching the R/C sites for a motor controller if this is what you want to do.

dunk.


Yeah, I realized that.  I think you would need a motor controller or something to recieve the pulse.  Without a pulse pin or anything, your motor is going to continually rotate in one direction.  It's worth a try though.

If not, you are going to need something to pick up the pulse from the RC reciever and be able to convert that into a signal for a DC motor.  You could apply this to a microcontroller or a motor controller, because it acts similar to a PWM.  The pulses could be interpreted and turned into a different signal.

I am not peticularly sure how to.  I'm in Business Law right now  ::)

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Re: rc servo/gearmotor questions...
« Reply #6 on: May 02, 2007, 05:27:45 PM »
this is a recommended dual motor driver that accepts low powered PWM from a servo reciever and outputs a high powered PWM to your DC motors:
http://www.dimensionengineering.com/Sabertooth2X5.htm
http://www.dimensionengineering.com/Sabertooth2X10.htm

RC hobbyists have many other types too called ESC, as ed1380 mentioned

Offline PrinceOfFlameTopic starter

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Re: rc servo/gearmotor questions...
« Reply #7 on: May 03, 2007, 12:39:06 AM »
wow you guys respond fast.. :o.it's going to control the motor for an automatic airsoft gun, so i'm fine with it only rotating continuously in one direction and speed. I knew what each of the wires were for, but wasn't sure if the red/black provided power for the servo electronics, and the signal line told the electronics what to do with that power, or if it was the way you explained. All cleared up now. Will post pics of finished 'bot when i get my camera working. Thank you for the help. ;D
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