Let's Make Robots!

True Roomba Hacking?

Hi, All!

How many LED's can you control?

Hi All!

I've got in mind a project that will involve a couple hundred LEDs that have to be independently controlled. I want to  make a clock where the individual seconds, minutes, hours, days of the month, and months of the year are represented by a lit LED. As the LED's representing seconds passes 60 seconds and goes to the next minute, all the "second" LED's go out, one "minute" LED turns on, and the seconds start over with all of them being dark. The process repeats indefinitely and cascades into hours, days, months. 

Unbalanced motor output

Ok, so I've got these cheap motors in the DFRobots 2WD chasis that are so unbalanced that the thing almost spins in a circle! I've been searching the forums and it seems like everybody's using PWM to adjust the motor output, so I've been trying to adjust mine that way. Problem is, I can get it just about balanced at a higher speed but then it's totally off at a lower speed. And it got me thinking about "why" the motors are unbalanced. Is there some kind of electrical imbalance within the motor that's causing it to run at different speeds with (presumably) the same input voltage?

Arduino motorshield problem

Ok, maybe someone with more Arduino experience can help me out with this, because it's making me crazy! I've attached two sketches. The one called MotorTest comes from the ADAFruit website and functions perfectly with by robot. It ramps up the speed of both motors going forward, then slows them down to a stop. Then it does it again, but this time in reverse. As I said, no problems with that. The sketch called navigation is the beginning of my navigation program for my new robot (see http://letsmakerobots.com/node/22697).

Battery charger?

Hey! I want to be able to put rechargeable batteries in my robot and then plug it into the wall to recharge...in other words, I don't want to pull the batteries out to recharge them. Can anybody give me some pointers on that?