Let's Make Robots!

LMR Planned Downtime

LMR will be down Wednesday 11 Nov. 2009 at 9pm PST (Pacific Standard Time, GMT -8) for some updates. Expected downtime is about half an hour.

Yes, this has been changed already ;) Due to the

Mr. Basic Challenge 2 ( autumn 2009)

challenge ending tonight, I don't want to mess up anybody's contest entry.


Sharp GP2D120 vs SRF05

Hi everyone,

I just completed the "Start Here" robot. I used a Sharp GP2D120 for the eyes and I used Fritsl's programming for the "Start Here" robot. I do not have any experience with programming but once I get this robot done then I will be able to learn more.

I have noticed that the robot is very slow, i.e.: It drives a little forward, then stops, and takes a reading, repeat. I assume this is because the robot is stopping to take a reading. If that is correct, then the SRF05 is better because it can take readings without having to stop the motors?

Where to put clamp diodes in a SN754410 motor controller circuit?

After a quick Google search, I couldn't find a schematic for the SN754410 with the clamping diodes. Instead I found this document which uses the L293. Could I use it to build the motor controller with the SN754410? What changes would I need to do to use one motor per IC to double the max continuous current? I have some 1N4006 diodes, could I use them in this circuit?




Salvage from a CRT TV and its remote.

A TV has just died (too dramatic a wording?) in my family where it went funny colours leading up to its not turning on. I'll need to check the plug fuse for them but it sounds like the CRT died after many years use. Rip it open time!

How can i measure the thickness of ice

How can i measure the thickness of ice.

Is there an easy way either with IR or Laser to do this.

Why :-  It would be far safer to send a robotic car across an ice lake to test if the ice is thick enough for skating - or even in a rescue type operation.

Any answers however lateral and crazy welcome.......

Encoders for servo mounted wheels

I have 2 questions, 
- First, when using a C-stamp (programmed using MPlab) is it possible to track the movement of a continus rotating servo so that I dont need to add encoders to know how  much the wheel has turned?  
This is an example of coding that makes 2 servos turn(if it helps):
void goforth(BYTE lp, BYTE rp, WORD t)
  WORD i;

Conflict with PWM2 output and osc input (PIC)

this is some data i got from the datasheet of the 18f252:



Digital I/O. 

Power toool motors - worth scavenging?

It's been a while since I spent any serious time at LMR, or indeed building robots. A pressing need to totoally renovate a Victorian house has taken priority so that I can generate enough money top pay the mortgage interest when rates rise again !

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. 

how to make a robot with the help of U.S ROBOTICS PCI I-Modern USR91-11 E466987. 1 0349


As a child

OK im new so didnt no what topic sorry for that.so the title says most of it as a kid 10-18-ish were you interested in electronics did you make anything?or did you just start robotics as an adult?

 (edit) i ask this because i am only a child so i wondere if there was any hope for me :] thanks for the feedback guys.

perhaps il just wait till i can actually buy some basic stuff but il still read up on stuff so hen i do get materials il be ready to start using my hands instead of my eyes

Picaxe and sound…

Anyone out there has experience with Picaxe and sound…
I am building a robot with a picaxe 28x2 and want to have some sound effects.
I can use the sound command for the bleep bleeps but I want to be able to have others like purr, ‘hello’ and fart noises. Anyone got any prewritten Basic sound code that emulates different effects?
And/Or a way to convert other sound format files so I can use in the Basic Tune command.
Hope this makes sense.

my first circuit

Hello everyone. any help would be great. I am trying to build this sound sensor circuit for my first robot useing a picaxe 28x2 - here- http://www.rev-ed.co.uk/docs/picaxe_sound.pdf but I am having trouble finding a couple of the components:

Capacitor value 1n0
Capacitor value 470n

Advice on accelerometers

Some questions about accerometers:

1) Which would be a good buy? I am putting together an order at seeedstudio cause they seem to have all the stuff I need at good prices. I'm thinking of throwing in this accelerometer, but I don't know if it's any good? I also saw that polulo has this cheaper model. So which would be the better buy? Or perhaps a 3rd option?

Interesting YDM sound clip found in the wild

Okay, so I'm looking at various videos for the wowwee Joebot today, and came across this one.

 Give it a good listen from about 0:09 to 0:15. Sound familiar?

arduino robot questions

hi will i have being wanting to make a robot for a long time and finally got the cash together to get the parts and whatnot so i have an arduino duemilanove micro controller, 4 full rotation servos and 2 sharp ir range finders one 4cm to 30cm range and one 10cm to 80cm i want to make a 3 legged walking bot a bit like swashbot2 but autonomes but being that this is my first bot i thort i would start with a simple 2 wheel ir range finder sort of thing anyway i have a few things i would like explained to me 

RC car controlled by PC or PDA using wireless communication

Hallo Everybody !

This is my very first post ! ))

I am doing the robo-project in the university. The main task is to build a robot using wireless technology that can be able to perform number of tasks that are sent from the PC.