Let's Make Robots!

Luxeon Leds - what would be the simplest constant current driver for them


I have just bought 5 of these 3W High-Power LEDs 

I could drive them off batteries direct ....

...however i would prefer to feed them with a "constant" but adjustable (350mA-750mA) current.


What would be the simplest circuit i could use ?.....

.... and would there be a way to PWM them?. 


Specs :-

3W High-Power White (6000-7000K) 130 Lumens - 140 deg

my super ex-girlfriend robot

Hi, everybody!

Does anyone have "my super ex-girlfriend robot" movie in his collection? I remember there was an episode with little robot carrying a flower or something... I think of building a replica of it as a gift to my wife. Anyone can help with screenshoots from movie picturing it or maybe even little clip cut out of it?

Thanks :)

I got some trouble over the first project.

Hello I am trying to do the first project of the robots, http://letsmakerobots.com/start I bought all the things needed but I got some trouble I dont know how to connect the sensor, its exacly the same as the project uses. I am getting lost at the part that says that because he refers to some other kind of sensor and than there is no image to understand how.

fritsldr with arduino

hi guys.
ive been having some problem figuring out the code for a fritsldr in arduino.
so far i keep getting this error:

error: expected unqualified-id before numeric constant.:

 error: expected unqualified-id before numeric constant in function 'void loop()'

PICAXE editor

I put this into the PICAXE programming editor

servo 0,150
wait 2
servo 0,225
wait 1
goto main

then I hit F5. A window comes up, downloads the program, and says "Download was successful! Firmware version A.6, Memory used = 18 bytes out of 4096." But nothing happens. I unhooked the sero and when I hooked it back in, it slightly jerked. I did this about 4 times until it stopped doing it. Now nothing happens. Is this something wrong with the electronics? 

qrd1114&qrb1114 phototransistors

trying to build line follower anybody tell me if the 2 sensors can be interchanged trying with the qrb and having trouble getting the motor to shut off ir will emitt and motor will run. will buyqrd if have to but will like to use ones i have

   thanks for any help



Hye, Sorry to bother you, I have some questions about a hexapod. I want to make the same like this http://webx.dk/robot-crawler/robot-crawler.htm  for my college project, if you have time to have a look on it, I want to know the configuration of the pcb board, an electrical schematics electric parts needed, what cpu usses, what kind of servos (can I use weaker servos?) . If you can help me, I would be very pleased, if can't..no problem. Have a good day.

Mega cheap breadboard


$4 for a 400 contact breadboard. I just ordered one so I'll let you know how it is when I get it. 


anybody got any qrd1114 sensors they want to get rid of i need 2 but will take more .need them fast

Just bought a dual PC board... I feel dumb.

Hey guys.

I just got home from the rat shack with a few of these babies.


Nobody in my town has breadboards, so these have to do until I get one from the net. Anyway, I'm pretty sure I get the idea of how to use one, but I'm hoping to find a short tutorial on the basics of using it. I know they're cheap, so I can screw one up and it's a non-issue, but I'd like to avoid that if possible :)