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!

| improve this question | | | | |

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

| improve this answer | | | | |
  • \$\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

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.