Let's Make Robots!

DIY not gate


i tried building a not gate (1 input only), not one i saw on the internet but i tried to make one myself. The problem is i didn't succeed. Now, i know there are loads of examples of how to make one on the net, but i opened this post because i'd like to know why mine doesn't work, so i can improve, hopefully :), my electronics skills.

Here it is:


CNC lead screws

Im looking to find some cheap lead screws ( http://en.wikipedia.org/wiki/Leadscrew) online . I was wondering if any one could point me in the right direction to find some cheap lead screws. I would guess that the CNC guys would know where to find them. If any one could give me a suggestion on which lead to use, i would appreciate it. I think i want a lead of about .500" per revelation. This is for my chess robot. I do not want it to be too slow.

Learning Electronics

Over the past weeks since I got my Arduino, I've learned a lot about circuitry. However, I still get headaches when I see schematics - and I'd like that to change.

What websites/books/PDFs/whatever would you recommend for somebody who's new to circuitry? 

ADXL335 vs MMA7260QT

Is the ADXL335 accelerometer better (faster, more precise, less noisy...) than the MMA7260QT sensor?

The ADXL335 based solution at my local robot shop is slightly more expensive, and judging from the product description it's "the holy grail". The MMA7260QT BoB on the other hand has a build in voltage regulator so it's usable with 5V which could come in handy. Though I'm primarily going to use it with an Arduino which seems to be able to provide 3.3V so that might not be a problem either way.

DC motor question

Is it possible to add position sensors to any dc motor? I want to buy 2 standard geared ones but am not sure if I would be better of buying a set of motors with postion sensor included. For now I don't really need them but it would be nice if would be able to use them in the future.


Getting Started

I want to get started, but I need help putting a decent started pack together. I know I need a board, download cable, etc, but what other toys should I start with?

 I want to be able to start off small: get a light to blink. Then move to getting several lights to blink in order or random order. Then I want to move onto attaching a motor and getting it to spin. Eventually I want to build a robot that will do all of my work, but baby steps right?

Serial transmission and when to initialise it


 I am trying to figure out how to transmit data from one atmega to another one via IR. Oh btw i am using arduino language.

First thing i though of was setting the serial communication by using serial.begin in the setup function. I tried that and i noticed that the LED connected to the TX pin on the arduino lights up as soon as i give power to the atmega. This is not really what i wanted, cause i'd like to have the LED off when not in use.

L293D question

I have build my own board with a PICAXE-18M and L293D motor driver.
The motor driver uses a seperate power source to power the motors.
When an output signal from the PIC is send to the L293D a LED shows the output is high.
All seems to work without problems; the motors do exactly what i tell them to do and so do the LEDs.

Accessing an array's size in C? (Arduino)


I'm doing a little series of flashing LEDS, sort of like the knight rider examples you see everywhere.


Anyway, I'm trying to make sure I've got clean code - and from what I understand of C, this is valid. However also from what I understand, the Arduino uses it's own form of C, so certain things are bound to be a bit different.

Here's the code I'm having trouble with.

How to hook up two serial outputs to one serial input

Hey all,

 So I'm working on a project where I'm using two processors and one of the things that I want to do is use one bluetooth device and have two microprocs communicate with it or send data through it. Of course this is not at the same time.

One chip would be the main com device, the other would send stored data when instructed to. I don't want to use one device as a passthrough as this would seem a little inefficient. so I came up with a schematic of what I think might work.