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Very beginner with this.

I am powering an analog LED strip (10 sections, total 12 V, 200 mA required). I'm using a N-MOSFET and an arduino to fade in/out the lights. From my calculations I don't need a resistor, but I feel weird about this (I haven't seen a schematic without a resistor). Is it okay to not have a resistor?

There is 11V coming from the VIN pin on my arduino, and since I need a max of 12V then I wouldn't need a resistor? And you don't use a resistor for amps, since the device will only pull what it needs.

Here is a picture of my setup ( which works, I'm just worried there is something I'm missing)

my setup

Any advice would be tops!

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Those little black SMT components between the LEDs are current limiting resistors. There's no need to add your own.

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  • \$\begingroup\$ Thanks for that. If I get more than 12V, I'm assuming i will need a resistor to bring it down to 12? \$\endgroup\$ – Lango Jan 8 '13 at 10:10
  • \$\begingroup\$ Simply I think SMD resistor components suffice here. It's very important to have a current limiting resistor BTW, because 10mV rise of the input voltage will leads to double the current. So it heat and create a dynamic resistor inside the LED, don't let that to be happen, always keep it externally. \$\endgroup\$ – Standard Sandun Jan 8 '13 at 11:15
  • \$\begingroup\$ @Lango, yes, you would want 12v or lower (for less current draw, but that means less brightness too). You could power it from a higher voltage, but that means the resistors are dropping more voltage, a higher current draw, which leads to a shorter life for the leds. \$\endgroup\$ – Passerby Jan 8 '13 at 13:09

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