Hi,
Ive got a simple white LED Strip. It has a + and a - at the end, which where I can provide power and ground. How do I control the LED Strip? How can I make the Arduino choose when it is on and off, using an external power adapter that provides 12V?
Thanks!
so many results...
How fast do you want to turn it On and Off? For occasional switching, a relay control will do.
For highspeed switching, like for brightness/fading control, a transistor is needed. N-channel MOSFET is very good for that.
The length of the strip and how much current it needs will determine the size of the transistor needed. AOI514 from digikey.com is inexpensive (50 cents), can control quite a few amps, and can be driven from Arduino directly.
AOI514 Alpha & Omega Semiconductor Inc. | Discrete Semiconductor Products | DigiKey
CrossRoads:
How fast do you want to turn it On and Off? For occasional switching, a relay control will do.
For highspeed switching, like for brightness/fading control, a transistor is needed. N-channel MOSFET is very good for that.
The length of the strip and how much current it needs will determine the size of the transistor needed. AOI514 from digikey.com is inexpensive (50 cents), can control quite a few amps, and can be driven from Arduino directly.
AOI514 Alpha & Omega Semiconductor Inc. | Discrete Semiconductor Products | DigiKey
On/Off as fast as possible! 
I dont have a AOI514 but I have this:
Can I use any of theese?
I have sent you a PM as well.
Can you explain why those non-logic-level MOSFETs wouldn't work, Mike?
Like the IRF520N, data sheet says Gate Threshold Voltage being 2-4V @ 250μA, max being +/-20V.
He's just turning on and off a 12VDC line, really. No data involved.
Wonder if he means to PWM it when he wants to switch fast fast.
Like the IRF520N, data sheet says Gate Threshold Voltage being 2-4V @ 250μA, max being +/-20V.
The gate threshold is not the voltage when the FET is on. It is the voltage where the FET just starts to begin to turn on. The FET still has a high resistance at the gate threshold, it is not until the full gate voltage is applied that the FET is fully on. Any voltage between the gate threshold and the full on level puts the FET in the linear range where it is in effect only partially conducting. Thus it will have some voltage across it as well as current down it. Basically it will get as hot as hell very quickly if it is conducting any significant amount of current.
The figure to look at is the drain source resistance, this is given at a specific gate voltage. You must apply at least that voltage to fully turn on the FET. Voltages above this value normally do not decrease the drain source resistance to any great extent, if at all.
Would the TIP120 not require a heatsink (depending on required power)?
sterretje:
Would the TIP120 not require a heatsink (depending on required power)?
You said it, depending on the current it is switching. That goes for FETs as well. In fact any power circuit might involve a heat sink. Do you have problems with heat sinks?
Not really. Point was that depending on mosfet one might not need a heatsink while with the tip it is nearly guaranteed that one needs one when using ledstrips.
I would put the TIP120 together with the non-logic fets in the "almost useless" box.
1.5volt saturation at 1Amp (50 LEDs).
A 5meter strip could work at half brightness, with a stinking hot TIP120.
Leo..
sterretje:
Not really. Point was that depending on mosfet one might not need a heatsink while with the tip it is nearly guaranteed that one needs one when using ledstrips.
No you are not. It all depends on the load.
