controlling 12v LED with arduino -- pwr supply question

hey, i'm looking to do something similar to this:

using a RBBB arduino and a salvaged PCB full of bright LEDs in parallel. i tested the LED array with a 12v battery and it lit up beautifully.

i intend to use the infrared camera extracted from a wiimote to read the position of a vertical infrared signal, and to adjust the PWM to the LED array accordingly.

here's my question -- can i power the arduino and the LEDs from the same 12v power supply? in the above link, the arduino and the LED strip are receiving power from distinct sources -- his arduino is powered via usb, not the 12v that is also powering his LED strip. is that a necessity?

thank you for your time

As long as the supply has the power requirement, why not?
I would use external LM7805 to step down voltage to 5V and then supply arduino. I dont like Arduino own regulator unless power adapter is 9V or less.

thanks mart -- just CMA

i'm referencing an instructable, where the fellow has done this:

here he's got a 7805 providing the arduino 5v via VIN ... "The 7805 will output a steady 5V to the microcontroller and dissipate quite a bit of heat. I like to do this because I don't trust the Arduino SMD voltage regulator"

is this worth doing? i know that rbbb has a less robust voltage regulator on its power supply input...

hahah i think you edited as i was replying. thanks for the confirmation!

Don't forget 270 ohm resistors between arduino pins and base of transistor. As Arduino goes high, the transistor looks like a diode to Gnd, need to limit current to not burn out the arduino pin. (5V - 0.7V)/270 ohm = 16mA. Maybe lower resistor to achieve 20, 25mA tops.

Funny that the guy doesnt trust arduino regulator neither.

Well, providing 5volt to Vin is safer than connecting it to vcc. Altough I dont know if arduino regulator can accept less than 6 volt, I guess it does. External regulator is safer IMO it is worth doing.

About the led power, ive never used that module so I dont know about its regulator.

If the 7805 is feeding into vin, the regulator must be supplying around 3v to Arduino..

The 7805 should go to 5v....

The 7805 also needs capacitors on the input and output.

Instructables circuits are normally crap and this one is no exception.