Let's Make Robots!


Batteries Got Exhausted in Few Seconds

I am building myself a simple robot car.

Simply, an A10 Olinuxino board  (my first false start because of the hard work of interfacing the ultrasmall 0.05'' pins header) interfaced with a Pololu Dual Motor Driver (https://www.pololu.com/product/2130)

To move forward, backward, left an right, I use a simple Web Interface which sends Ajax commands to a Python Web Server I wrote.

Finds you the perfect Led for your project in a fun way
The Fun Led Checker Tester was something I needed for my workbench for a long time. Whenever you have an idea you start by going through your parts. Leds are in … Read more

Calibrating current sensor Wild Thumper Controller

Hi guys,

I have tried to follow the instructions regarding calibrating the current sensors of the Wild Thumper Controller, but I would like some clarification.

question about arduino and supply current

hi guys, I just bought a ucam ttl jpeg camera for my arduino and have some very basic questions.

Reading the dataset it says that to power the camera it require 3.0V to 3.6V DC range nominal 3.3V. So I plug it into the 3.3V pin from my arduino mega, setted it up and it worked.

However, im a little confused about the specifications from the datasheet.Namely it says that

Supply Current (ICC) VCC =   3.3V    58(min) 62(typical) 76(max)   mA

But the current draw from the 3.3v pin, according to the website is only 50mA.

QRD1114 Resistor Values

Hi all,

I'm using a QRD1114 sensor for a line-follower. Datasheet: http://www.fairchildsemi.com/ds/QR/QRD1114.pdf

Im hooking it up with this schematic:

However, I'm unsure how the value for the 10K resistor was calculated? It's acting as a potential divider, right?

For the LED im guessing that the value of 220 was taken from doing:

R=(Input Voltage - Max Forward Voltage)/(Optimum forward current)

Turning on a motor using a transistor (question)

I'm building a fire-fighting robot for a science expo and everything is fine so far (at least the electronic part is!) but I`m stuck with the fan motor. I`ve already fried a N3906 (don`t know what I expected).

Power Screwdriver Motor

So I bought a few power screwdrivers for the main drive motors for my new robot project. I have started creating a rocker bogie suspension system out of PVC pipe. This suspension will require 6 drive motors. The power screwdrivers run on 4 AA batteries. So the motors are 6 volt. By browsing the interwebs I figured out that one AA battery supplies about 2.4A. So I figured that each motor would require 9.6A. But since I have 6 motors I would need 57.6A. This would require a huge SLA which would weigh about 20lbs and cost around $100.

Can this breadboard handle 2A?

I plan to use 5V at 2A (10W) with this breadboard. It`s pretty small and cheap but I`m afraid it might not be able to handle 10W. 


constant 4.5 V supply using batteries?

how may i get a constant power supply of 4.5 Volt

using batteries?


Stepper motor holds at full current and makes noise, smooth otherwise


I have the following:

EasyDriver stepper motor driver

Bi-Polar stepper motor 6 wire

I am using Red/White and Yellow/Black, which means I'm using half coil.  My understanding is this allows me to use the full current (and presumably have more holding strength).

i dont know what this LED is ... any ideas ?

ok i have a few of these LEDs and i dont know what they are for i think they might be IR LED, i have tried putting a power source through them from 3-9V and it does nothing. any ideas at all i have about 500 of these my friend gave me and not a clue what they do... 

ESC says dont use above 3500mah battery

My ESC on the AGV says do not use a battery above 3500mah (something like that maybe a bit greater. I peeled the sticker off already)  with it. Well this limits my driving time, and i would like more. So i am wondering why would there be a limit like this on it? i thought current was asked for, why would there be a limit for how much could be supplied? I want to wire my batteries in parallel to get longer driving time, but am afraid to with this warning. Can i raise my current and lower my maximum speed?

Introduction Sometimes it is necessary or at least ingesting to know how much current your circuit is drawing when connected to the USB port. You could detach it … Read more

(Solved!) Low current from Arduino Output (Arduino Start Here robot)


EDIT: LED problem solved thanks to RobotFreak. I forgot to set the pins to output mode using the pinMode command. As RobotFreak points out, the Arduino sets all pins as inputs by default. I added a For loop to set all the pins to outputs, and everything worked great.

void setup() {
  pinMode(13, OUTPUT);  
  for (int pinindex = 0; pinindex < 14; pinindex++) {
     pinMode(pinindex, OUTPUT);  // set pins 0 to 13 as outputs

Motor drivers?

Does anyone know of high current ( 2.5 Amps per motor) motor drivers which are compatible with Picaxe AND PWM? I need to drive 2 motors.

Common Electronics Knowledge Questions

Hi LMR. I have already made a robot, as you may know, but all I did (on the physical/electrical side of things) was plug a few cables into the pre-made servo ports on the Board of Education, as my copy of Electronics for Dummies told me to do. I read the entire thing, but they explained a few things in a way I didn't understand. Like the names for stuff, and what each means. Until now, I thought voltage was a measure of battery capacity. I FAIL, I know. I've sorted it out, so now I know about amps and volts, but I have a couple technical questions regarding electricity.