Let's Make Robots!


basic obstacle avoidance, two LEDs blinking and otherwise,

*Complete* is not really the correct word for it.  While trying to set up the four pins with screw terminals on my high power project board, my buddy and I managed to completely ruin B.6 and B.7.  After throwing around a lot of ideas, we can only imagine throwing a 330 ohm resister array chip in where the L293 is and connecting a bunch of servos up to it to make it a walker... maybe.  It depends if the board is set up in a way where that is really feasible.  The other option being to buy ANOTHER high power 18m2 project board and move the chips over to it, but I don't like that idea.  If feel like the best idea would be to cut our losses and get ourselves a 28x like the start here robot, since it is so well represented in all of the projects here.





This robot may seem overly simple to most of the people on this site, but my friend and I have absolutely no experience with electronics or computer programming. We are having a few problems getting enough juice out of the cheap little motors I got at Radio Shack, but we are going to try using bigger motors and adding capacitors to cut down on noise.

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Tonight I am going to be fixing my engine issues, as well as trying out some new code.  My buddy and I have a few questions that I was wondering if I could put forth to the group.  We are considering turning this thing into a pseudo start here robot.

1.)  does it matter how small your servo is for mounting the sharp IR rangefinder?  The smallest ones I found were also the cheapest (which is backwards in a weird way to me)

2.)  Is there a reason that I won't be able to use my Picaxe 18m2 highpower project board in the start here robot?  I understand that it uses a 28x something or other, but for the amount of inputs and outputs I feel like I can make it work, but does it have some lack of computing strength that I am unaware of?  I am unfamiliar with how servos work and I could be missing something in regards to its use as well.

3.) On a totally tangential note, are there any robotics conventions in the midwest United States?

Thanks for reading even if you didn't reply.  I will post another picture if it all doesn't catch fire tonight.


To connect servo you have to solder pin to one of the holes between picaxe chip and motor driver. If you use motor driver chip use only b.0- b3 holes. Connect yellow or white cable of servo to a pin. Connect brown or black cable to ground and red one to power. (any place of power or ground is okay).

its very easy to use servo commands in picaxe, if you pin is in B.0

Servo 0, 150

pause 1000


150 is center, usually you can use values between 75 and 225, depends on servo. HXT900 and SG90 are quite nice cheap little servos found for example dealextreme.com and hobbyking.com

thanks for the info, since I ruined the output holes for B.6 and B.7, using the board with a few servos is my only real option besides throwing it out. 

Quick question, don't you have to put a 330 Ohm resistor between the picaxe and the servo?  Or is the noise negligible?

I have heard many people saying its ok without resistor and i have had no problems driving servos with picaxe without resistors. But its you choice, i don't know if it has any risks in it.


Is it sure that you really happened to ruin the holes. I think it shouldn't be  very easy :) Have you tried removing solder with desoldering bump and schratching it away? You can anyway drive motors with fet outputs and steer with a servo or anything or use continuous rotation servos or anything, there are much options what to do with your board anyway.

yeah, the little rivet pushed out when we tried to remove the screw terminals we were using.  I probably will just use the board for a different project.

Yes, we love videos :-) Mogul did already poit this out..."keep cost down" is also one of the main subjects here...

Your questions, my answers:

1. No, the smallest servo will do the job, any 9g micro servo is good.

2. I am not familiar with Picaxe but it should work. Processing power is not the issue, it will be enough.

3. This will answer one of the US guys here ;-) I just know that in NY is the makerfair and LMW will be there as well.


Regarding lumi's item 3, Maker Faire, which is not just about robots, but is definitely a cool event, has multiple locations. The big ones being Bay Area (California), Kansas City, Detroit, and NYC.

Cool, Detroit is only like 6 or 7 hours from where I live.  Thanks

I found myself a Tamiya twin motor gear box for about 8 bucks and picked up a sharp IR rangefinder while I was at it.  Expect updates when that comes in a week or two.  The actual coding in Basic will probably be the hardest part for us.  I think I have it working as is, but I might post the code after I test it out with the new gearbox. 

You might want to consider learning how to convert servos to continuous rotation. That would give you a geared motor and single pin control in one condensed enclosure and mounting tabs to boot. :)