Let's Make Robots!

DC motor control with Arduino

Ok, so i had this running just a few days ago, but then when i tried to assamble it didnt work out for me. Now I cant even get this simple DC motor running from the arduino, or to be more precise; the motor will run at a very low speed. Connecting it directly to my two 1.5 batteries it will run at full speed, but when trying to control it from the Arduino it wont work for me.

 Here is my setup:


and the code is dead simple: 

How do you get your bot to choose the right direction?

I have been trying everything to figure away to get my robot to choose the direction that have the greater distance.  I can't seem to figure out whats wrong.  I tried to figure something out.  One time I wrote it different and it would wait till it got to the last case and turn right no matter what. This is my code. 

How to Hook Up a Potentiometer

I googled it and I still cant measure the resistance of a pot using a multimeter. I put 4.5volts on the left pin and tried to measure using the middle pin and the right pin and nothing. What am I doing wrong?

Quick question about this simple circuit?


[yay, I got the image up!] 


 I know this is very very basic, but what the heck, I want to make sure that I put everything together correctly.



So would c and b be wired together and connected with a 10k resistor and then c goes to 0v and b goes to a 22k resistor then serial in?

Picaxe programming jack?

Anyone know of a place I could just buy the little jack to connect a picaxe microcontroller to my computer?


Thanks. :) 

Darlington driver switching different voltages??

 hi all i've just stumbled upon the joys of robotics in the last week

so i'm a little green, I've read some darlington threads already but i didn't find an answer.

darlington drivers

Hey all.

Calculon has a question about the uln2803 darlington driver. He has a datasheet that says "the darlington pairs may be connected in paralell for more current-carrying capacity."   Calculon wonders how this is done?

Would that be pair of darlington pairs? And if he wanted more current capacity than that, what transistors would he use to make his own d-pair?

Calculon thanks you.

Wiring a 3.5mm audio jack to an 8 pin picaxe?

Ok, I want to be able to easily make my boards programmable by wiring a 3.5 mm jack to an 8 pin picaxe microcontroller. However, I'm not completely sure which wire goes where to do this. The jack has 5 pins, anyone know which goes where to program a picaxe 8 pin and hook it up to a battery?


Thanks :) 

Sound Sensig

I want to find a simple, easy, small, solid circuiti to detect environment sound pressure level

can anyone post a  good schematic?


SR05 Help on first robot

Hey everyone,