Let's Make Robots!

The future of hobby robotics?

Hello dear LMRers! Not long ago I launched a blog at ohmnivore.co.nr . For a start, I wrote about an idea I had in mind for a long time and that has me wondering; why are there so little RaspberryPi-powered robots? I post this to stimulate a discussion about the RPi (I'm aware a lot more people will see it here, not at my blog). I'm too lazy to edit all the links, so the original version with working links is here.


Sonar RADAR GUI Windows APP (SensorVal,Degree)

UPDATED 3 Sonar Sensors 360 Degree - 120 Degree Servo Rotation

Improved for multi sensing. You can now use THREE Sonar sensors to display on a graph.

Improved Serial port handling, Wire-Tension is coming soon, Serial Port Availability[Menu Item] is also coming soon.

Cutting Acrylic sheet

I've been asked how to cut acrylic with a hot wire cutter - I made my own and there are a few plans for how to do this on instructables etc. This was my take on the idea which I find works OK for me... - see the file attached

Interface Arduino w/ Sharp IR sensor

I have a Sharp GP2Y0A700K0F IR sensor that I want to connect to an Arduino decimilia. The data sheet says to use (3) wires for connection (pin 1 to ground, pin 2 to voltage, and pin 4 to analog pin) but the sensor has a 5-pin housing. Should I find a 5-pin female to connect with? or is there a better way to make the connection. Please help! I have been searching for how do this interface for a while with no success....my first robot. Thank you.

2 Wheel Drift

I have a 2 wheeled robot - 2 GM10's with little thin wheels.  I've hooked them up to an arduino with an L293.  I have it going forwards, backwards & turning well enough.  The problem is when going forward, it seems to drift to the right slightly.  Any suggestions as to what the problem might be?  Do I need wider wheels?  A proper castor?  (ATM, the front of the chassis rests on the ground). 

Basically, what I'm asking is, with 2 small motors and thin wheels, can I expect a bot to go in a perfectly straight line?



Hi guys. I have to admit i do not know much about these kinds of transistors... i mean, their difference.

I have to get a large current pass through a wire, but after having read articles on wikipedia about mosfet i don't really know why i see them on, say, motor drivers instead of BJT transistors. One thing i don't know about is whether you can find logic-level high-power BJTs but i know there are logic-level FETs, like the IRLD series. But again, if you want to switch a BJT on fully then maybe you could just arrange them into a Darlington i guess.

Why am I an idiot and IR transistors...

Here's the encoder part http://www.sparkfun.com/datasheets/Sensors/QRB1114.pdf


This should be simple... resistor pulls the input pin high, transistor clicks and pulls it to ground.

What am I missing?!?!?



Animatronic NIN

Uh, yeah. Nothing like taking a happy fun memory and turning it to Nine Inch Nails :

FYI, the Rockafire Explosion was an animatronic band that played in a kids pizza chain, Showbiz Pizza, in the 80s. Kooky, happy, family songs, played Beatles Happy Birthday song for kids, etc. Now only in collectors and inventors hands. 

And now, after the Showbiz's have closed, this.  Wonder if they'll cover Pantera?

UART level translation, what type of translation IC is required?

I have two devices, and need to figure out how to translate between them for 2 wire UART.

U-Blox NEO-5G, 1.8V
Input low:  0.22V (MAX)
Input high: 0.91V (MIN)
Output low:  0.4V (MAX)
Output high: 1.4V (MIN)

Telit GC864
Input low:  0 - 0.5V
Input high: 2.1 - 3.3V
Output low:   0 - 0.35V
Output high: 2.2 - 3.0V

UBlox -> Telit
LOW: .4V (MAX) -> 0-0.5V   (WORKS)
HIGH: 1.4V (MIN) -> 2.1-3.3V (DOES NOT WORK)

Tips for making a robot multi-task

I have a robot, and my robot has a brain. However, my robot's brain can only think about one thing at a time. I can set I/O pins high or low, and they will stay there until I change them, but that isn't going to work. Here's the deal:

Oh_Oh Robots


Hello Everyone. This is a news flash from Mexico. David Cuartielles is now  here spending the summer in Mexico, given workshops about creating small robots. The Oh_Oh robot was introduced at the Faro de Oriente. This small bot is
commissioned by the Spaniard Cultural Centre and The Faro de Oriente. This bot is an open source  project created by Cuartielles and Yang from the Physical Prototyping Laboratory from the University of Malmo, Sweden.

Here you can see a few pictures of the bots. Cool, aren´t they?


The circuit I am using is attached.  I know the circuit works because it will move the motor forward and reverse on 9V.

When I apply 9V DC to it, things work as they should.  I can use my transmitter to forward and reverse the motor.

When I apply 12V DC from a lawn and garden tractor battery, the TIP 127s begin to smoke.  I have already burned one out.

After replacing the burned TIP 127 again it works on 9V but again apply 12V DC and more smoke.

Voltage regulators in parallel

Hi guys, i'm planning to make a robot which requires 12V,5V and 3.3V power lines regulated from a approx. 15V battery.Would it work if i used 3 voltage regulators(one from 15 to 12V,one from 15 to 5V and another one from 15 to 3.3V) connected in parallel? Or is there another way of getting 3 different regulated voltages from one power source (the 15V battery) thanks. 

Not Robot but still awesome video.

If you have ever flown an RC Helicopter, you will love this.