Let's Make Robots!

List of good online shops for bot parts

I was wondering where online most of you go to shop for parts? Can we construct a master list of important websites here?

This list is from the URLs I've gathered from the various tutorials:

Reads the latest status from Twitter.com and then verbally speaks it with a couple different mood options.
Using a
UPDATED: I've added the video of Steve's reaction to the robot.  Also, here are more details about the robot, construction and … Read more
This is based off of the "First Robot" tutorial and uses the Arduino Decima board instead of Picaxe; it's also the first robot I've ever built. Read more

Picaxe 18 and Ping

I just picked up a Parallax Ping distance sensor from my local Radio Shack and am trying to figure out to how hook it into my Picaxe 18 project board.

The ping uses a single pin for both input and output.  It first requires a trigger pulse to be sent and then it responds with a variable length pulse that determines the distance.  Can a Picaxe pin be switched from output to input?  If not, can I connect 2 pins to the single Ping pin?  Normally I would jut go ahead and try it, but I don't want to fry my Picaxe or the sensor.

Where can I learn more about capacitors?

One of the things that still baffle me today is when to use and how to select the correct capacitor.

I've read through this chapter about capacitors: http://www.allaboutcircuits.com/vol_1/chpt_13/index.html

Afterwards I feel I undestand how they work, but still don't have the two most basic questions answered: 

Sharp Range Sensor gives inconsistent results

I'm trying to use a Sharp range sensor (http://www.pololu.com/catalog/product/136) on the Picaxe 18x project board but I seem to be getting bad results.  When the sensor is not facing anything within range, the analog input jumps around 95 - 110 in the debug window.  When an object gets closer the results seem to be more accurate, but still jumps around a little bit.

Not sure how to use the Picaxe 18x Project board

I just got my Pixaxe 18x starter pack in the mail (YAY http://www.sparkfun.com/commerce/product_info.php?products_id=8326) and the one thing that seems to be lacking is complete documentation. :)

All the output pins seem to go through the darlington driver and the pins coming from it are all negative (-) -- not positive (+).  Usually when you set a pin to "high" it goes positive, right?  This seems to reverse that.  I'm not exactly sure how to connect this to the motor driver or do serial output.   I hope this question makes sense.

This is my continuation of the comment thread started here: http://letsmakerobots.com/node/763#comment-2036 The goal is to come up with a gearbox transimission that … Read more

Which Battery Pack for the PICAXE 8 Pin Proto Kit? (9 volt?)

I just received the PICAXE 8 Pin Proto Kit from Sparkfun (yay) and it comes with what looks like a 9v battery snap clip but the datasheet says that I cannot use a 9v battery.  The text states:

"ONLY USE A 4.5V or 5V battery pack, not a 9V PP3 battery, as the power supply."

So what kind of a 4.5v or 5v battery packs uses the snap type connectors?