Let's Make Robots!

Controlling lot of LEDs in parallel with Arduino & transistor

Hi all,

Got some questions about using trnasistor and resistor with lots of LED all together. I am not good in electronic planning but only drawing sketch out as image below.

Try to using as less resistor as possible so I only plan to use one and I know Arduino couldn't handle that many LEDs so transistor will be used as I know. However, I am not sure how to connect these points as identify in image below from A~G. Can anyone help me or sugeestion how this should be connected and what type of transistors, resistor should be used?

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Grownups only

"Gigahoes."  I've only watched the first one.  Not Citizen Kane but there are a few good laughs.  (5yr+ LMRians will know how my tastes run.)

Trex Motor Controller i2c read while using rc

I am starting to put together a rover using Wiild Thumper and the TRex motor controller.

I am having some difficulties getting i2c working reliably from a Raspberry Pi 2 running Ubuntu 14.04

While I am continuing to research my issues (possible future post coming) I decided to give the RC connection a try.

My question is if it is possible to access the i2c read only while using the RC as I would like to try out code for monitoring the current draw and battery voltage.

GY-521 and motion in a straight line

Hello all

I have a few questions about using GY-521 MPU-6050 gyro. If you have experience - please, help. 

1) Different sources indicate different allowable voltage - 3.3V or 3.3 / 5V. Can I use it with my 5V Arduino?

2) Is GY-521 enought for motion in a straight line of such platforms as dagu 4wd/6wd wild thumper?

Many thanks in advance.




cooling fan 2

Hi LMR wizards,

I'm wiring a cooling fan into my robot, it's a 5v fan and will be blowing air across my voltage regulator's heatsink. The regulator is used to supply power to my servos, some LEDs, etc.

As far as my knowledge extends, a DC motor shouldn't be powered from the Arduino, without using a motor driving circuit, as a motor can feed back electrical power and damage the chip. I don't know if this is still the case, if it's just running from the Arduino power, or only if running from a pin?

Servos maxing out

Hi, I recently got some servos online with intention on making a spider bot controlled by an arduino. I've connected them up to a seperate power source (4x AA) to the board and with the first set of 3 no problems. But as i've gone to add more they started acting rather strange. When I apply power to the servos they sometimes all max out try to go beond their limits, if I disconnect the power from the servos and board and restart they sometime works, but only for a short amount of time before going back to maxing out.

How to build a Arduino room to care a flagging tree scientifically?

Here is a flagging tree in our office, but due the busy work and the room are not suitable for the tree’ s growth, it is flagging now. I read a short elecrow blog about a project making use of kinds of crowtail modules that aims to collect the data of the tree such as light strength, soil moisture, temperature and humidity of this tree. In this way, people can know the current situation of the tree and then take actions accordingly. 


Dagu Rover 5 PWM Settings

Hey All,

So I've been building a rover using a (Dagu) Rover 5 Chassis, a Rover 5 Driver Board and an Arduino Uno.

It's wired up fine and I can send instructions back and fourth to the motors no problem but what seems to be an issue is the speeds which the motors are turning at. If I can set the speed at 100 (i.e.

Adding a Raspberry Pi Camera to Elf the Robot

Robots are a lot of fun.

Robots that stream video over WiFi are even more fun!

Elf Raspberry Pi Robot @ http://Mikronauts.com

(click on image for larger version)