Let's Make Robots!

Using PiFace but still using I2C

I got a PiFace Display in the mail not too long ago, and just cracked it open.
I got it as a tester to write a review, because I wanted the LED display and the infrared on it.

Making a PING sensor control a DC motor

Hi, guys. I'm kinda new to this robot-scene. I've been doing it for about 3 days i bought a arduino uno r3 and a few other odds and ends to make a simple robot. ive got 2 DC motors(3v), A PING sensor, and everything else to make a robot(don't feel like going into detail lol). I know how to run the motor and the sensor by themselves but i need some help making the sensor and the motor cooperate. Any ideas


P.S. i have programming knowledge so i dont need it (dumbed) down lol

Motor Arm Length Calculator

Below is a picture of what I'm trying to build. This is the motor that I'm using, which has plenty of torque.

Servo problems!

I'm having a lot of problems with the servos I'm using to build a quadruped robot. I should start by mentioning that I bought the servos from Dagu like 4 years ago, BUT most of them had never even been unpacked until recently.

The problems are the following:

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.

Parts Prices (In US Dollars)

Here is the analysis I have done so far. I didn't look everywhere, but I did learn 2 things.

  1. You can't buy everything from 1 place
  2. It is cheaper if you buy from outside of the US on some parts

Here goes my summary: (For all intents and purposes, when priced in £ double it for US dollars. It is a bit less than double, but after your credit card company charges a fee to convert the purchase it will be close to double given the current rate of exchange on 5/7/2008)

Starter Pack (Picaxe 28 with USB cable)

Servo problems

My Picaxe 228x1 arrived today with the servo upgrade pack. I have followed all instructions but can't get the servo command to work. It appears to be trying to turn clockwise past the stop - i.e. it turns all the way and then buzzes. I can get it to move ok with pulsout commands so I don't think that the servo or any connection is fundamentally broken. The following is my program - the servo 0,150 is the command that isn't working as expected (any position I give seems to give the same result)

Anybody got any ideas what I've missed?




The goal is to allow 2 PICAXE chips to speak with each other via IR.

What receiver and transmitter have you all had success with. Where can I purchase? (links?)

Thanks all.

Software PWM

I was hoping to avoid wrighting my own software pwm for the pic but it looks like i've arrived there.  the motors and tracks I hot glued toghther don't drive straigh so the only way I can think of fixing it is to use PWM to slow down one motor.  I know I could use the one hardware pwm to slow down just one motor but thats going to be used in the future for somthing else so I have to create the pwm myself in software.

Help with 555 circuit.

Well, I have got the 38khz distance sensor working in picaxe form.



Now I am trying to wire-up a stand-alone unit with a 556. Now I know this is a RTF(data sheet) moment and I know the resistor/resistor*cap/2 (or whatever) equation, but the final circuit is still above my head. Are there any of you circuit guys out there that can do a little drawing for me? Maybe with a couple pots for fine adjustment? I plan on the final output going into a picaxe using the pulse-in command.

Thanks in advance.


TENET TECHNETRONICS is now an official Distributor in INDIA for Arduino Boards

TENET TECHNETRONICS is now an official Distributor in INDIA for Arduino Boards an open source Electronic Prototyping/Development Board, an easy way to procure boards in INDIA. These boards will help your  electronic ideas to become a reality. We also host a range of electronic boards - Micro Controller, VLSI and Embedded boards. We host a wide range of electronic components to cater your needs.

Boards we currently distribute
    Arduino Mega
    Arduino USB/Arduino Duemilanove
Arduino Pro
Ethernet Shield for Ardunio

Picaxe PWM and servos

I have tried using picaxes PWM outputs on 2 robots now with limitted success. The biggest problem I have is that the PWM frequency although adjustable is very high (typically 16KHz with a 16MHz resonator). This causes the windings of the motor to have a much higher impedance resulting in poor torque. When I use the setfreq command to drop the clock speed very low (500KHz) then I get good torque even with a low dutycyle but the processor is so slow it is almost asleep.

Big choice of servos in Europe


I'm making a robot arm, and I need 1 shop to buy all my servos from (legal reasons).

Problem is, the shop has to have all the range from powerful and durable high-torque servos with full ball bearings (about 25 - 30 kg/cm), to lighter standard, to even some very lightweight mini servos.

So far the shop with the best choice is http://www.active-robots.com/products/motorsandwheels/servo-index.shtml, but I would be very happy if someone coined me some more or better options :)

Hello! I'm new here


Hi there. I have seen a few videos from this website. I've even been told a few time to sign up, so here I am! :) Glad to meet you all! Lots of fun projects on here. I've been looking through the Robots and Blog area, some real neat stuff.

I'm a robot builder also, sorta, kinda. I spit out new ones often, so I may not have time to post them in the Robots section. But I really like the active forum here! I'll probably be around often. 

Here's a few links to some of my robots if you're interested: