Just getting started, need help picking parts (motor and servo possibly?)

To start, I know nothing about electronics. I learned Ohm's Law and how to calculate resistance of a circuit diagram in high school, but I never touched a physical piece of electronics in my life. I know nothing.

I always wanted to though, so I got the Arduino starter kit, and the book (and I do know how to program), and I got through it in a day, and I love it. Blinking/fading lights, measuring ambient light, buttons, all great.

But I want to build a robot of some kind, which moves around, and my starter kit doesn't have those pieces. I bought the "Motor Shield" which I guess can control the pieces I need, but I don't know what exactly I need to get, and my budget is getting tighter.

So, what do I need to buy, for this? I have some cheap toy cars which could provide a base and some wheels, but they can't move on their own, so I doubt Arduino can convince them. I suppose I need a motor (which probably means something more specific than "thing that moves other things") and a servo (it turns? I saw a youtube video) but I don't understand what factors would make them compatible or not, and I'm worried about buying the wrong piece, and either wasting the money or burning out the parts I've already got.

Any part recommendations would be great, or more specific pages on how to figure this out myself, I'm just a bit overwhelmed.

Haha, I'm in exactly the same place as you, just a step or two ahead. First of all, a servo is the same thing as a motor. You can get a stepper or continueous motor. Steppers rotates to a specific point and a continuees motor keeps spinning at the speed you specify.

After I worked through everything imagineable with the starter kit and the parts I had originally bought, I looked online and found a kit called Parallax BoeBot for Arduino. It comes with a body to mount your arduino on, the Board of Education sheild (it has four servo connections, it's own breadboard, and it comes pre-assembled with the kit), two continueous servos, a little (but suprisingly loud) speaker, two infrared LEDs, two infrared recievers, two photoresistors, some wires, touch sensors, whiskers, resistors, and everything else you need to make a fully functioning autonomous(controlled on it's own) robot. Parallax has very good step-by step tutorials for the kit on their website. I finished all of the tutorials in about a week.

That should give you a bit of a kick-start to your learning curve. I think it cost me about $120 and you'll get a lot of really good parts and tons of experience by building it. I finished that kit a week or two ago and I'm using what I learned to make my robot controllable by the arrow keys on a computer with a GUI displaying the robot's stats.

You can use those toy cars as an "outer shell" for a robot. You can put your arduino and electronics in the toy car and attach the wheels to motors to make your own little RC cars.

by the way, Adafruit.com is a great place to buy Arduino-specific electronic parts and kits.

Good luck...

I have used steppers from a printer to do stuff. They are easy and cheap to get and work.

Find yourself a cheap "full-function" R/C car (something by New Bright or similar); it should be able to go forward, reverse and turn left and right, minimum. You don't say where you are, but if you have any thrift stores or such that sell old toys, you'll generally be able to find something there. Try to pick a car that originally used a 6, 7.2, or 9.6 volt rechargeable battery. Make sure the wheels turn properly, and that nothing is broken; if you rotate the rear wheels, they should rotate smoothly, with no wobble, and the meshing of the gears should be smooth, with no grinding or skipping. Also make sure the tires are "round" (sometimes when these toys sit, especially in the heat, the tires can get deformed). Make sure the steering mechanism seems like it is in good condition, and that the wheels return to "center" (after adjusting the centering mechanism on the bottom).

Once you have done this - you will likely have a good vehicle to hack with. You can then check the receiver PCB - if it the TX2/RX2 chipset, you are almost golden - check this long thread to learn how to hack it (to use the on-board motor drivers):


If not - then you'll have a couple of options: Figure out the h-bridges that control the motion and steering yourself (difficult but not impossible, but having some knowledge of electronics would help) - or completely remove the PCB and install your own motor driver system. I note that you don't say -which- motor shield you have; you won't be able to use just any old motor shield, you will first have to measure the current needs of the drive motor and steering actuator before purchasing the proper motor driver. Likely, though, a couple of L298-based driver boards would work (once converted to "bridged" mode). An L293 (or equivalent) based motor shield probably won't have the current capability (the L293 can only source approximately 1 amp per channel, and can't be bridged - the L298 can source 2 amps per channel, or in bridged mode, 4 amps).

Ok - I know that was a lot, and is probably over your head more than a bit. If so (if all of the above seems like a foreign language - says the American) - then STOP. You should get a beginners kit or the parts for such, and concentrate on the simple examples available in the various books and such on the web; otherwise, you'll be stuck in frustration-land in no time...

To B3nj1771:

Thanks for the recommendation! This site looks great, the writeups are helpful, and it's much cheaper than radioshack.

To compuslave:

Do you mean a 3D printer, as in made-to-order parts? Or from a disassembled office printer? That sounds promising.

To cr0sh:

What you're describing is something I want to do someday, but I'm not prepared for it yet. Too many things in there I don't understand! But I appreciate the long writeup, I'll be following it soon enough.