Let's Make Robots!

IR and ultrasound based positioning beacons

I have this idea for a positioning system based on IR+ultrasound beacons. It is very simple, and I'm surprised that I can't find anything like that already in use. I guess there are some problems that I can't see, so I wanted to ask you to point the flaws in my idea before I invest time and materials into chasing a pipe dream.

The goal is to get an accurate position of a robot inside a room that is decorated with some additional beacons. The positions of the beacons are known to the robot, so that it can position itself relative to them.

6WD Differential Turning issue



I have just completed building 6WD by follwoing the tutorial here.


1. 200rpm 12v DC motor Max stall current: 300milli amp and normal current :60milli amp and 2kg torque each.

2. 6X125mm Off road tyres

3. 12v battery with 4.5ah

4. L298N Motor Driver with Max 2amp output.

5. Aurdino Mega to control the drivers and aurdino UNO for transmitting wireless signels to Mega.

The issue:

what i notice is that the vehicle with PWM from 150 to 255 its able to move forward and reverse with out any issues.

The iPad of Dr. Moreau

Is anyone else getting weird renderings of the site on a tablet? Here's a screen cap I just landed:
ld5cWi8.jpgNever mind that johnnyalpha seems to be the logo out header, and that Duane's project picture is in the wrong box. What really disturbs me is

That ain't BDK.

How to sense the beginning and end of a ramp?

Hi guys,

I am a complete novice to building robots, yet have been


Im trying to use these module/shield to run 2 DC Motors it that simple ......i thought..... (at moment Arduino sketch only to run one to see if i can get to work) I have attached pictures of my set up and as much tech detail about Bridge as I have hop helps thanks a lot to any who can help/guide me in right direction

Connection to ardunio clone

enable A on pin 5 (needs to be a pwm pin)

enable B on pin 3 (needs to be a pwm pin)

N1 on pin 2 conrtols one side of bridge A

IN2 on pin 4 controls other side of A

not enough voltage for IR receiver to warrant high

Hi guys,

I bought a magician chassis from sparkfun that comes with the wheel encoder boards, but without the sensors. After doing a small amount of research, I thought I try it out making the encoder myself.

I bought a pair receiver and transmitter from a local shop, 2 pins each encased together side by side. I tied both the receiver and transmitter to the 5V output of the arduino board, and and the other end of the receiver to the input pin of the arduino.

Feedback on PopPet instructions

Hello all!

Firstly, just thought I'd let you all know that PopPet is going really well. Everything I need has arrived and I am now boxing up all the bits and pieces.

One thing that still needs finishing up is the PopPet build instructions. These aren't going to be included in the kit, but rather available on the website for viewing or download for offline use (due to costs of printing). A QR code is going to be in the kit to take them to the instructions.

Best way to extend LCD flex cables?

Hi All,

I'm in the process of acquring a CMOS camera, and I'm looking for a way to distance the camera from the circuit board that it is connected to.  I havent' counted the pins, but it looks like the LCD flex cable might have approx. 20 pins (+ or - 5 pins).

I don't yet know their spacing.  The options I'm thinking of are:

Parametric robot rover

Hi, I am just a beginner working on his little project, which is to:

create parametric design for robot rover ... (just rover), because I like a lot to programm the CAD model (actually written in Python which exports SCAD code that renders it)

and yeah, I want to try to 3d print everything (of course the "smallest" version possible to try it) at the start... (just because I don't have anything else ...). Final version should be made also from parts made on water/laser cutter

so here is what I have done so far (alias configuration I am working on):

FrankenCNCRouter: Re use electronics, or replace?

Ive pulled the back off the FrankenCNCRouter, and quite surprised by what ive found!

As far as i can tell, the box on the bed is just motor drivers, My knowledge of electronics leaves a lot to be desired, but as far as i can see this is a line of beefy transistors?, a line of VERY beefy resistors mounted on the bed to disperse heat, and a few other odds and sods (regular reistors, diodes and a big cap)

The 6 white terminal pins to the centre go directly onto the stepper motors (which are 8 wires each, but two are doubled up on the pins, pressumably common coil connections?)

Picaxe vs Arduino

Hey guys,   I only have experiance in visull programling like mindstorms.  I was gonna buy the starter robot to start figgureing out how to do real programing but in the box, several advised i go with Arduino  instead.  I certainly dont want to learn a dead language, so, what do I need so I can use the Arduino  instead to build the starter bot?  Is the voltage requierments the same?  Can it use the same yelloe chip and the same motor controler thingy.  Is the rest of the start here bot part compatible with the Arduino  board?  If not, c

PingServo.attach(6) causing DC Motors conected to L239D not to spin


I have a test circuit using an Arduino UNO that is wired to a L293D chip on a seperate breadboard. I followed the "Goduino II" schematic.

The L239D has two small DC motors connected to it.
I also have a PING ))) Sensor sitting on top of a Servo. The Servo is connected to pin 6 and the Sensor is on A4 on the Arduino. The sensor works fine. 

BRAND New Actobotics Mini Channel from ServoCity!

Now the versatility and strength of Actobotics channel on a smaller scale! 

Arduino MEGA2560 stopwatch using registers

Hi guys!

I'm trying to make a stopwatch with 4 separate 7 segment displays using timer register. I already have a functional circuit and I found a similiar code HERE  that uses this register.
BUT. This code is showing in MM:SS format. And I want SS:100/SS. What I need to change in the code to have this format?

Printing with trimmer line

As many of the shout box regulars have found out i have my printer up and running. when i finished it i had no material to print with and a massive desire to see my monstrosity work amd remembered something i had read online.People were experimenting with trimmer line (the stuff thats used in weed wackers/weed eaters etc...) but last i had looked into it deltas and bowdens were the new and most people were running 3mm filament. well after looking around i found .065 inch line which measures out to ~1.68mm.

Soldering tutorial

Hey there

When first starting out on electronics, I found soldering really frustrating, mainly because I was missing a few good tips and tricks that make it a breeze! So I've just finished off a video tutorial, and thought I'd post it here in case anyone finds it helpful :)



The robots we've always wanted

In a recent thread, some LMR members started listing robots they loved and which inspired them, either real or from sci-fi novels or movies. My interest in robotics also finds its origin in our great sci-fi canon, and people listed some really cool robots I'd never even heard of. I thought it may be interesting to split this off as a forum topic and hear about even more robots out there and how and why they inspired our fellow LMR members to build robots themselves?