Let's Make Robots!


ComMotion Motor Controller Shield

Need help with the ComMotion Motor Controller Shield. Searching at this site for info on this shield leads to many pages with 404 errors.

Examples of broken links related to ComMotion are:

Need a good dc motor driver?

Hi all I have a quick question. I have a couple DC drill motors and gear boxes and I wont to make a robot. I am looking for a 20ish amp motor controller. I either need a dull one of two single ones. What do you all recommend? It needs to be able to plug into a regular receiver since I am going to be using a Dx7s and a simple dsmx receiver. I could be biger than 20 amps just I thought 20amps would be a good base line. I want to find something cheep like under $50.

Biped Howto: Moving servos

+++ UPDATE (12-march-2014): Rename title as "Biped Howto".

Hi, I will try to explain, in a very simplistic manner, the way in which servo motors can be controlled.

Servo motors are controlled by a PWM signal, in which the active part of the signal (known as duty cycle) define the amount of degrees the servo will rotate.

Controlling powerful motors

Hello guys,


I want to control a powerful motor not like the ones used (servo motor) I need something of the ones which work on 110\220


I am not sure if it is possible using picaxe, if so is there any tutorial or has anyone done this before?


Obvioiusly it should be powered externally and controlled by picaxe


If this is not possible what can the strongest servomotor provide me? Can it for example to move the steering wheel of a car?



How to Choose an Electric Motor

Finally I am sick of mowing my lawn, and am starting to plan a robotic lawn mower.

I would like to use one of these batteries (12V Li-ion) on the mower.

Suggestion arduino Motor Shield with Brakes



I have built my first robot (ultrasonic sensor, 2 wheels, 2 dc motors) using  he following motor shield(bought from ebay)

New V3 Arduino Driver Motor Controller Shield L298N 2A 2 Motors Module

Unfortunately my robot always bumps into walls. It turned out that I am not able to apply BRAKE.

Transistor based H-Bridge

Hello everyone I realised after burning through 6 L293D's that they were getting old. I hated them mostly due to the fact that they were fragile. I also burned 3 of them because of static electricity. So I decided to try and make a cheap H-Bridge from transistors. This is just a test circuit what I need to know is: is the circuit correct, can this type of H-Bridge handle more than 2 Amps depending on the transistors used, and do you guys have any suggested modifications if it is wrong.

As usual my design has to do with water and something that my brother asked me to have a look at. What he needed was a way to launch a probe with a controlled … Read more

Seeking Advice: Selecting Electric Motor and Power Source for Musical Robot

Hello All! This is my first post. I am a relative novice to electrical work and robotics. I have experience wiring my own guitars and putting together effects pedal kits, but that is essentially the end of it.

12mm output motorgearbox

Hi I am looking to build a 4WD robot with 4 independent motorgearboxes. I have some wheels that I would like to use that have a 12mm hex hub. I need a motogearbox with high torque, and a threaded bar or a tapped hole at the end of the output shaft. Has anyone seen/heard of a motogearbox with these specifications? 

Motor just buzzes, no movement

I'm trying to follow this tutorial:


Now, while I'm not too familiar with Breadboards, since I dont have one, and can't afford one right now, I've had to take it into my own hands to carefully solder wires between the points. I seem to have everything done, but when I start the program, the motor DOES start a buzzing sound (don't hear it when the program is NOT running) which indicates I'm at least partway right.


So my questions are,

Raspberry Pi Lego car

Hello all,

I'm making my first robot using Raspberry Pi. My robot looks like a car with three wheels. Two of them are in front and have connection to motors, The third one is behind and it's no connection to motors.

I'm planning to use 2 simple motors (for each front wheel one). For now my robot weight 260g, and i have to add two motors and battery and i little of more constuction for holding motors and battery. I'm already found which type of motor should i use:

Motraxx MOTOR X-FLY 400 or Moteaxx MOTOR X-FLY 280.

rover 5 w dagu 4 channel motor control hardware problem?

I am running the dagu Rover 5 (4 motor/4 encoder verion) using a Mega2560 and the Dagu 4 channel motor control.  This is my first attempt at a robot, but do have some experience using several models of Arduinos and motor controllers. 

The code I used is from this first message (by Nick Gammon) and wired exactly the same: http://forum.arduino.cc/index.php?topic=82618.0

Shaft coupling from 0.125 D to 0.25 square

Hi, hoping someone can help me with what I think is a pretty basic question:

I have 2 motors with a 0.125inch keyed (or D) shaft.  I need to connect it to a 0.25" square socket (vex tank tread driver).  I assume there's some sort of coupler or adaptor that could help with this?  I've been looking for most of the afternoon and haven't found any good solutions but I imagine it's largely due to me not knowing where to look...this is my first robot so I'm a bit new to the whole connnecting a shaft thing...  many thanks for any suggestions or thoughts.

motorcontroller board [FIXED]


I am trying to build a segway, I know how I am going to make it, but I have been struggling to get the motorcontroller to work for days now.

I attached an accelerometer and a motorcontroller to an arduino uno. When I tilt the accelerometer 2 indicatorlights on the motorcontroller change, so this signal must be right. But when I measure the voltage at the motor output I get only 10-60 mV.

I tried using more and using less Volt (5-15 V) on the m.c. board itself. (I attached it to an old model train transformator)

Please Help


My DC motor stopped turning fast


I am working on a car like robot that has two 4.8V DC motors, one on each side (Differential drive) , the two motors were working perfectly fine but suddenly one of them stopped turning fast as it used to be. i measured the voltage across the motor and to my surprise the voltage was even higher than the other motor that is still working. I am using L298 H bridge as a motor controller.

in addition, the motor does not even start until i give it a push by hand.

any help would be really appreciable.

Goes insanely fast for it's size.
Going Whole HOG (or GWH) is my first foray into building a Hemispherical Omnidirectional Gimbal drive type robot/RC device. I first encountered the HOG drive right … Read more
all in one robot control board
This project aims to create an all-in-one robot control board. Unlike the arduino platforms, this board will contain servo drivers, motor drivers, accelerometer, … Read more

Servomotor torque requirement for a quadruped robot


I'm planning to build a quadruped robot soon. My design is very similar to the design in the following link.


I'm not that good at mechanics. I like to calulate the torque required for each motor. Is it ok to use the formulas/procedure in the following link to design a quadruped shown in the above link?


photocell with motor, no programming

Hi, im new to the forums and I need some help running a dc motor with a photocell without any micro-controllers.

Heres the list of parts I have:

-Tip120 transistor

-1n4004 diode

-1k resistor


-solderless breadboard

-jumper wires

-9volt batter with battery connector thing

-a small dc motor (i dont have much information about it except that it seems to run on 3.3volts:( )

28BYJ-48 stepper motor

hello, I'm working on a new project and I'm using this small stepper motor from yourduino.com. I'm controlling the position of the stepper motor using a 10K potentiometer and it does rotates according to the pot, but it jitters at any position. What could be cousing this jittering?. I tried the knob code from arduino.cc and still jitters. I replaced the pot with a 1.2 kohms fix resistor and it does not jitters when stoped. Is the code missing something? HELP, no really HELP.

#include STEPS 100

Stepper stepper(STEPS,8,10,9,11);

int previous = 0;

void stup ()

L298 problem

I'm making a robot and I'm using an L298 to drive 2 DC hobby motors (specifically, the tamiya twin gearbox). For some reason, the L298 give out 3.4V on its outputs when applying logic low to the corresponding input. Does anyone know why this is? I am going by the example schematic in the datasheet, using 5V for logic power supply and 9V for motor power supply.

Artist, first time robot creator

Hi everyone. I'm an art student who's doing my instillation for my Advanced Drawing class on automated art and the creative power of robots. Needless to say I'm quite lost when it comes to the mechanics of it. I got ideas, but ideas don't mean shit if they're not backed up by knowledge. That's why I'm asking you guys for help, and hopefully I can take the advice and use it to make some really effective pieces.


Rotate a Shaft - 60-120 Seconds Per Revolution - Bidirectional

I need to rotate a shaft very slowly.  Somewhere between 1 and 0.5 RPM.  I need forward and reverse.  I don't need position sensing.  External control will be two buttons -- forward and reverse.

I'm aware I could use a stepper motor and a controller, but that seems overly complex for my application.  I need close to 360 degrees of rotation and I'd *prefer* that it rotate in either direction as long as power is supplied, so a servo motor seems like a poor match.

Custom Gearbox

Hey all I have built a few small scale bots and am now working on a larger 200lb bot. I was wondering if anyone had constructed their own gearbox for a DC motor. If so how did you do it and what kind of gears did you use?


Thank you for any direction you can supply.


Timer K2579RS Help

I recently got this:http://www.vellemanusa.com/products/view/?id=350494

My problem is that I need to attach a motor to the timer so that once the time ends, the motor turns. The problem is that I havn't been able to get that. Please help. I need this by tommarow!! Thanks!


Driving a ride on toy car motor

Hi folks,

As part of a project I'm building I need to create a rotating platform and I recently salvaged a DC motor and its gear train from a ride on toy car, so I thought if it can scoot a child around it should have enough torque for this application. The problem is that I'm not sure how to drive it.