I was tasked with creating a robot to do whatever I wanted it to do as a project for this class. I'm fixated on the idea of an RC Car, and was starting to formulate how I wanted to do it.
I intended to use an IR receiver to collect sensor data to be processed by the arduino, into an l239D motor controller, into two DC 100 rpm motors.
The thing is, I'd like this thing to be as fast as possible. From my limited knowledge of circuits, I thought, more voltage = more power = more speed (Bit more complicated than that, I know).
After research, I figured out there's a 5V supply required internally for the driver motor, and up to 36V (Maximum, I'd probably use between 9 and 18 (two 9v batteries in series)) to power the motor itself.
My question is
A) how feasible is this idea of using two different power sources, and if so
B) Can I ground them both together on a breadboard (if I used a 5V power supply for everything but the motor power, and then the 18V for a motor, can I wire them to the negative "grounding line", persay, on a breadboard, and wire that into the grounding port on the arduino without damaging anything?), Or do I need to wire the two grounds seperately (opposite sides on the breadboard) and then wired them into two different grounding pins, and if that's the case.. Can the arduino handle grounding 18 volts, or do I need to add a resistor beforehand?
Extra; I'm not very great with circuits, so if you could be very blunt and thorough that would be FANTASTIC.
Start by selecting the motors.
Then you will probably find out that the ancient/inefficient L293D is not capable to provide a lot of power.
And that it's equally ancient/inefficient bigger brother, the L298, has the same problems too.
They have one thing in common though. Cheap. Maybe that's why they are so popular.
Leo..
Wawa:
Start by selecting the motors.
Then you will probably find out that the ancient/inefficient L293D is not capable to provide a lot of power.
And that it's equally ancient/inefficient bigger brother, the L298, has the same problems too.
They have one thing in common though. Cheap. Maybe that's why they are so popular.
Leo..
What would you suggest I use instead?
I have a project requirement to stay under a fixed price, so I'm going for cheap, few day functionality rather than long term sustainability...
Is what I'm leaning towards. Plastic case, metal geared economy motors, advertised at 100 RPM, unless I should go lower or higher, I'm completely open to input... The object would be a lightweight (probably less than 2 pounds).
An L293 on a 12volt (max) motor supply would just be ok.
There are two of those chips on a v1 motor shield, if you want to go with a shield.
A v2 shield could squeeze a bit more speed out of the batteries, but you want cheap.
Leo..
Wawa:
An L293 on a 12volt (max) motor supply would just be ok.
There are two of those chips on a v1 motor shield, if you want to go with a shield.
A v2 shield could squeeze a bit more speed out of the batteries, but you want cheap.
Leo..
I guess my next question would be, should I use two power supplys, one for the Arduino and the 5V required for the internal functions of the l239D, or should I wire it all to a 12V battery.
I guess in my mind, wiring 12V to the Vmotor slot on the l293D, (I think it's Vcc2.. might be wrong) would squeeze more speed out of the battery, especially because there isn't current being taken up by everything else going on...?
Might just totally be wrong, I guess I'm just slightly confused
When considering how to route ground and power lines, realize this. Even wire has resistance. And, resistance * current = voltage [good ol' Ohm's Law].
So, consider that something like a motor is going to draw relatively large currents -- especially when starting up, and when a physical load is placed on the motor. So, the motor should have its own, separate power and ground lines. And, yes, connect the negative side of the motor's supply, to the negative side of the 5V supply, but do it as close to the power source [e.g. batteries], as possible. UNLESS, you wind up using something like a motor driver shield that uses optocouplers [also referred to as an optoisolator]. Then, wire the thing up per whatever instructions come with it [typically, the logic ground and the motor ground are NOT tied together].
But, if you think in terms of wires as resistors, that can guide your wiring decisions.
Have a look at the motors and speed controllers used in RC racing cars that you can buy - that will give you an idea of the type of set up you will need.
