That layout is fine, the 12V will run warm as it sourcing the 5v current also. Make sure to heatsink it.
I'd go with Logic Level N-channel Mosfet with Low Rds for the transistor, connecting LED Cathode's to ground.
WIll run cooler than NPN transistor at that current.
Maybe this one
You need capacitors on those regulators, see the data sheet for exact minimum values but I would put a 0.1uF across the input and output of both regulators plus put an additional 47uF capacitor on the input of the first regulator.
The FET needs to have the load connected to the 12V, so source to ground, drain to load, other end of load to +12V.
Grumpy_Mike:
You need capacitors on those regulators, see the data sheet for exact minimum values but I would put a 0.1uF across the input and output of both regulators plus put an additional 47uF capacitor on the input of the first regulator.
The FET needs to have the load connected to the 12V, so source to ground, drain to load, other end of load to +12V.
do i really need caps on the regulator. the 5v one i use to power my servo is doing fine with out them
ok one last thing, the data sheet for the voltage regulators call for a 0.1uF and a .22uF cap
i would like to know if i can use these 0.1uF, 0.22uF 35V Tag Tantalum Capacitor
i would like to know if i can use these 0.1uF, 0.22uF 35V Tag Tantalum Capacitor
Yes you can.
I wouldn't actually recommend it for a safety critical circuit because when tantalum capacitors fail they fail short circuit and could cause a fire but many people do use tantalums in this sort of circuit. I suspect a short would be protected by the power plug in your case.
Why not buy a 12v regulated wall wart, and power the Arduino from it as well as the lights, through either barrel jack or the Vin pin? That way, you don't need to mess around with regulators.
Your schematic isn't right. You need to connect the -ve side of the 15v input to Arduino ground and the source terminal of the mosfet (and the ground terminal of any regulators you may be using). The resistor goes between the mosfet gate terminal and the Arduino output pin.
dc42:
Why not buy a 12v regulated wall wart, and power the Arduino from it as well as the lights, through either barrel jack or the Vin pin? That way, you don't need to mess around with regulators.
Your schematic isn't right. You need to connect the -ve side of the 15v input to Arduino ground and the source terminal of the mosfet (and the ground terminal of any regulators you may be using). The resistor goes between the mosfet gate terminal and the Arduino output pin.
because the arduinos regulator can not supply enough current to run the LEDs and it would over heat
well i wont need the resistor between the LEDs and the mosfet because i am using a pre-made LED strip.
with the resistor between the arduino and the mosfet what value should it be and with the caps for the regulators will 50 Volt Ceramic Capacitors work well.