Let's Make Robots!

AVR Interrupt Question

Hi all, here is my dilema:

I am attempting to fashion my own rotary encoder to detect wheel rotation speeds.  My approach is to use a disc with a slotted pattern cut into it and a photo interrupter.

This is the photo interrupter I have on hand: http://www.sparkfun.com/datasheets/Components/GP1A57HRJ00F.pdf 

Complete noob here


I just came across this website today and it looks like a vibrant community.  I'm interested in learning robotics as a hobby and have no idea where to start.  I'm a pretty good programmer, but I come from the web world - programming web and middleware in the enterprise - Java is my most proficient language. Although the languages may not be applicable in robotics, I'm hoping my experience in programming will give me a head start.  I have some experience with electronics from college, but that’s about it.  

Electronics questions

I'm pretty bad with electronics... I'm more about putting things together I guess. But I need a little help:

I don't understand how a power source (battery) has amps. Isn't current (amps) a function of voltage and resistance through ohm's law? Is it possible to blow something with too many amps like it is with volts?

While we're at it, what happens when you put a voltmeter behind a resistor? Where does that number come from?

Rovio on Woot for $99 today!

I just thought you all would like to know that woot has Rovios for $99 today.


 - Brian


Okay, I broke the rules. Yes, I'm ashamed. But I don't give up. Hopefully this is the right place for this article...

TSWLhexaPOC? Well, Two Servo Watt's Linkage hexapod Proof Of Concept would have been a bit too long for a name, wouldn't it? I stumbled over a few hexapods controlled by three servos. Well, it should be possible to walk over a plane with only two of them. If this is possible using some simple gear it would save money when building small robots. How did I find a solution?

Begginner robot Problems(yet again)

Alrite so I have my robot made (and hopefully the write way too) but when i go to do the first command in the "First robot how to" guide my computer tells me i need to hold the reset button and do PICAXE>run then let go of the reset button when i get a status bar to pop up.  what deos it mean when it says "PICAXE>run?

Blob Tracking on a Windows Based System

I was just wondering if anyone had experience with basic blob tracking on a windows system.

Robotics Studio/Visual programming language has a blob tracker service, but I haven't found any info on how to implement it..

Does anyone have any suggestions?

Reducing amp drawn on a dc motor

Hi there! 

Is there any easy way to limit the amps drawn by a electro motor? I ordered some good ones but am playing arround with a standard 360 one now. It comes of an rc plane, is small but rather amp hungry. Don't want to blow up the motorbee.

Best regards,


pretty cool fountain

Found this while surfing the interwebs. Thought it was interesting and I'd share it with ya's folks

It uses some common components(well, aside from the uv leds that aren't available at your local hobby shop)and a pic.

 Now just makes me wonder how to do something like this...code wise.