Let's Make Robots!

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.


Tunes for Picaxe

Zjink the file, unzip it, make tunes with your picaxe.

(Oh yeah, this file is 100 or so different "tunes" for picaxe. All are .bas files, cut-and-paste ready)

Nichrome wire

I'm working on a project (shh, don't tell) and I need a little coil of nichrome wire. Some research tells me that a big roll can be bought for like $15 USD but I honestly don't need that much. It's the heating element used in those car cigarette lighters (the kind you plug into the socket...you know what I mean) and (i think) toasters. If anyone has a roll laying around or an old toaster or lighter, would you mind mailing me a little bit, like three or four inches? I can give you a dollar or so or stamps or something, and I have some salvaged parts I could trade you.

Basic Triagulation Positioning System

3 Friends and I are building an autonomous tennis ball collecting robot for a 4th year design project for our undergrad.

We need a way for the robot to keep track of its position on the tennis court (in doors) and we are thinking of using 2 beacons to emit signals with a receiver on the robot. Has anybody done something like this before? Has anyone heard of pre-packaged solutions that do just this? A USB module would be ideal (we are using a netbook to control the robot), but we are not at all opposed to building the positioning system from scratch. 

Arduino Motor Control

I have just purchased a new robot chassis for future projects to be built on. Heres a link...



i am unable to find very much info on the motors in the chassis, but i am wandering what sort of motor controler i will need. all i know is that it uses  2 x 9Vdc motors  that are run of 6AA cells. im using an Arduino as a controller and would like somthing thats relitivly easy to code for.

Problem with I2C mode of 16f877a

I am having problem with I2C mode of 16f877a. I wrote a code for I2C ranging mode of the SRF02 sensors. At first I thought the problem was with the code, but then I debugged the circuit a little; the code is as below:

Building a Universal RF Remote - Questions

More Recent UPDATE: the competed remote can be found here. Thanks to fritsl and rik for their respective helpfulness.

UPDATE: Attached (and blurrily pictured below) is my schematic that i think will work for this remote. Yes I drew it in paint, Yes it took too long:

*The "To Breadboard" leads are included so that the remote may also serve as a portable power supply.




SRF02 and 16f877a in I2C mode ranging


I am trying to test SRF02 ultrasonic rangers I just bought and to do that I connected them as required, and wrote a program in MIKROC for I2C transmission. My problem is that everytime I power up the curcuit my PIC burns. I connected pull up resistors to each of SDA and SCL lines; could it be that these resistors impose too much current into SCL and SDA pins of the PIC? Maybe I have to use a buffer between bus and 5V? The code is below. I am new to embedded programming so any of your comments would be of much use to me.

Thank you,


The Code:

Best...Arduino products help?

Hey everyone I'm new and everything but wanted to know:

What Arduino board thing (Nano, Mega, etc) should I use as a beginner. Before I get answers, I need to specify my question with another inquiry: HOW would I get this project on the road? My project plan is to make a swarm of robots that follow instructions given by the "QUEEN" of such, which is simply a moving computer. Would there be a way for my robots to wirelessly get instructions from the queen? And if so, does this affect what Arduino product I go with. I await your answers.