Let's Make Robots!

Arduino EMF detector

Arduino EMF detector !!!

Interesting Sensor project from makezine

Does UART require a pullup resistor?

I am trying to understand how UART communication works.

I have not read anything stating that pullup resistors are required for UART, but conceptually some type of pullup is in fact required because otherwise there would be an unknown state.

Is it part of the UART standard that each device on the bus must have it's own pull-up resistor?  If so how can this be because if the pull-ups are of different voltage then the state is again unknown.


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)

Picaxe28x1 kit and those ribbons..

*warning* Extreme newbie questions below..

I have the 28x1 starter pack and it includes 3 ribbons but I'm not sure of the correct/best way to use them..

Is the red stripe at the top of the ribbon supposed to indicate something? 

My First Robot - Motor control for tracks

Hello all

So, I've been lurking this forum for a while now and finally decided to make my first robot.

I started out reading the "Start here" guide - and it's a really cool guide by the way :)

Motors and Arduino

   Hello, is it possible to control regular small DC motors with an arduino board? If yes what limitations do I have?  can I use the PWM feature to increase decrease their speed?+

what about servos, do I need a motor driver or can I control them with just an arduino? 


How Should I Make My Robot Remote Controlled?

Hey all!

So I'm working on a robot that I will enter in to a state wide competetion and it has to be remote controlled.  I have no experience with making a remote controlled robot so I was wondering if ayone could suggest a good receiver and sender for a robot with 4 outputs.  Also I would like some tips on how to hook it up.  Thanks!


Salvaging an old motion triggered light

The other day I found this in our local garbage dump:




I have been trying to figure out its wiring diagram using a multimeter.


Using Frisls "Clean navigation" with a Sharp GP2D120 IR Sensor?

Greetings from Finland.

1) Is it possible to use frisls "clean navigation"- code with a sharp GP2D120 IR sensor? I know after looking at his code that the distanse readings are backwards (on a sharp closer distanses are greater), but if I changed them would I be able to use his brilliant code as a base? 

2) what is the differenses on SRF05 and sharp GP2D120 other than one is a
ultra sonic and the other is a infrared.Idon't meen number of conections but speed as in using themto almost constantly return the range


step-up or joule thief or.. ?

I`m trying to convert the wireless doorbell outside from battery to a renewable source such as solar or wind. My problem lies in that the battery required is a 9v.

My first thought was to produce a high enough voltage to charge the 9v but that might require more solar panels than I have. The 2nd idea was to use a lower voltage battery or super-cap as replacement and stepping up the voltage to 9v. I haven`t taken any measurements of current usage but I don`t imagine it could be more than a couple hundred mA while pushing the button and much lower in idle.