Let's Make Robots!

DC motor question

I was walking through Lowes the other day, and found this great trash can that looked like a robot to me. I was able to pick it up for super cheap!! What I want to do is add two DC motors to the bottom and a caster wheel. I want to make this robot carry my books around school for me. I am lugging more text book weight than I ever did in the Army with my ruck sac. My physics book alone is killer.

Trash Can

High-End Radio Gear

My remote control car met the end of its life last week. (smashed into a wall...) So, i salvaged everything i could, and found some interesting stuff:

A Motor Controller

Transmitter/Reciever (can control 2 servos)

5 batteries, ranging from 1500 to 2000 mAh

I also had lying around:

2 radio transmitters

a second switch for the motor controller


I need:

-arduino proto shield

-lots and lots and lots of polymorph. like a shoebox full. a shoebox from someone with canoes for feet.

Windscreen wiper motor

Hi All,

Got my hands on 4 new windscreen wiper motors for 40 euro in total. Which should get me started with building something nice. The seller told me it is one for a VW Golf which I checked on other sites and they look the same.

Of course I opened it up and it has a couple of metal connections (see picture 'inside') on the gear wheel which connect to wires going to the outside (to make the wipers go left and right I presume. That would make a nice rudimentary odometer don't you think?

My PROBLEM (if it is...) NO SPECS

H-Bridge NPN vs. PNP

I usually make a H-bridge with 2 NPN and 2 PNP transistors but I recently noticed that there´s allot of schematics on the net showing it with 4 NPN transistors and I started wondering what´s the right/best way to do it??



I was wondering...

Can you controll an electromagnet with a PICAXE?

if so how?

Many thanx in advance :)

Totally Lost. Totally, totally lost.

What I need is a wheeled, remote controled machine that can go into crawlspaces as little as 4" high and as tight as 4" wide, grab a line securely, and allow me to drag the line out. Estimate that the maximum the wieght should ever be is about 5lbs, with forward and aft cameras and lights (assume the microscopic "spy" type cameras and only a few inches of veiwing area for the light).

Arduino questions


i'm from germany and i'm trying to build my first Robot with the arduino Platform.

I've desided to build my own shild for the arduino.

It should be able to drive two motors and to connect 4 -5 servos to the arduino.

The first problems with the L293D Motordriver are solved and I've done that it works and avoids objects.

Today my servos arrived and i tested my shield with the servos.

and then the first problem:

Confusing Motor selection topic, 12V DC reversible Gearhead YG-2732 vs. 6V electric YM2712


Aren't all DC motors reversible? Why is this gear head motor YG-2732 getting praise for being reversible while this normal 6V DC motor does not get the reversble praise?

I never heard of a store bought DC motor that can only go in one direction.

Which one should I get? Value or Performance?

I'm building a holonomic drive robot platform and jaycar is the only place I can find to find the proper motors.

If there is another place, tell me.

Or should I just use hobby motors?

Can you help me decide?

DAGU parts price list for LMR members only

I have now removed the pricelist as we now have distributors in Europe and America.

European customers can buy from: Arexx Engineering or Conrad.

American customers can now buy from Robot Shop.

Fun books for Backyard Shenanigans

Not really robot related, but sometimes I get so frustrated with work I need to blow off some steam. Enter Backyard Ballistics, a great book that teaches you how to make spudguns, mini-catapults, and smallest of all, matchstick rockets.

This, and a few more books are written by William Gurstell, the man who had a website called backyard-ballistics.com, that sparked my brain into more research into amateury-ness.

Hello! I was wondering if anybody could help me determine compatibility issues :(

Dear Robot enthusiasts,

Hello all!  This is my first question on here so please feel free to critique my writing style.  

Controlling a bots turning movements

Im thinking of implementing something like whats shown below. The bot scans from left to right, in increments of say 20 degrees, storing each value recorded. Then based on these readings, moves in the direction where there is no obstacle. Now here lies my problem. I cant figure out how to get near precise control of the bots turning movements. I can, say make it turn 90 degree left or right; but how do i make it turn to an arbitrary angle from a halted position? Is this possible, or am i being over enthusiastic?

Swap: Looking for GM10 motor and wheel

Im looking for somebody who wants to trade me a GM10 geared pagermotor for something that I have. I have a lot of stuff, so if you have the GM10 motor and wheel, and want to trade me it for something, let me know.

Controlling a DC Motor (Mabuchi FA-130)


I'm trying to run a Mabuchi FA-130 (#18100) DC Motor, it uses 3V and 2.1A when stalled. However, I did some measures and when I forced the motor to stall it consumed nearly 4A, but I think this was some sort of coincidence since It has never happened again.

I'm using a circuit similar to this one posted by Simon Z in his post:


(By Simon Z and taken from http://letsmakerobots.com/node/7990)

Reading USB mouse data in linux - somebody else C app and my python

Here is a slightly modified (added in hs and vs) c utility, and my python version. they will read the linux /dev/input/mouse data and convert it into status and x/y deltas

i noticed my python app seems quite different to the c app. not quite sure - default int()  types in c must be signed, i dont know... my second two bytes for x,y have MSB set if they are negative, but this value is also set in bits 5 and 6 of byte 1 from what my python tells me..


comments welcome!

What distance sensors are better and best?

I am working on a much faster & stronger version of Robot Wall Racers, using quite fast RC-cars

I want to use lasers as distance sensors, but I think they will be a little over budget, altough this is a paid for job :)

Yes, SRF05's clai, they can detect a broomstick on 3 meters.. but in reality they are not stable before say 1.5 meters.

1.5 meters when you are traveling at 25km/h is NOT a lot, when you even are set up with drifting tyres.

Programming help, sharp IR mounted on servo


I am trying to control my bot using a sharp IR sensor mounted on hitec servo with arduino mega. The pseudocode i have so far is as follows:

1. Set servo at 90deg and read IR sensor value
2. If val > 200, then stop the bot for a second
  a. Turn servo 0 deg completely and read ir val
  b. if val < 200 then turn bot left
  c. else turn servo 180 deg and read ir val
  d. if val < 200 then turn bot right
  e. else if cant turn right or left, reverse a bit and then turn the bot 180 degree and go straight.

360 Range Finder

I just received my SRF05 and I can't wait to start using it.  While I was thinking about it, it occurred to me that I always see the SRF05 mounted on a servo, which allows maybe a 180 degree field of view for a robot. I wondered if anyone ever mounted a range finding sensor on a motor so a robot could see in every direction. 

I think I may try to build a 360 degree range finder, but I wanted to open this as a topic and get some ideas. Here's what I'm planning. Let me know what you think.