Which MOSFET to use? As we’re dealing with to220 package here, they’re all pretty powerful. Now you can control the LED strip the same way you blinked a LED on a breadboard. A resistor of 220 Ohm is recommended between the Arduino pin and Gate, but is not strictly necessary. The N-Channel MOSFET is ideal for our purpose, because it sinks current, is placed after the load, so the connection is extremely simple: Source to Ground, Gate to Arduino pin, Drain to a color channel of the LED strip (usually a colored wire). There are tons of tutorial on their use, like this one. The most obvious way of connecting LED strips to an Arduino is using N-Channel MOSFETs. It is a good idea to add a master MOSFET to the 12v circuit to be able to disconnect the LED strip without disconnecting the power (say, with an IR remote). It will also work, juts don’t forget to connect the grounds from both sources together. You may also connect the Arduino to 5v and the power line of the LED strip to 12 volts. Voltage regulators tend to heat a lot and their heatsink has a rather small footprint, so it’s better to check its temperature after some working time, to be on the safe side. There’s one thing however that you should be aware of: the heat. So, it’s perfectly safe to connect everything to one 12v supply: the LED strip directly, the Arduino via its Vin pin (don’t use the power jack the strips +12V line MUST be connected directly to the power supply). On a Nano it sits on the back, but is easily recognizable. In any case, if in doubt, you may check this instructable to find out more about the voltage regulator. Its power rating usually states 20 volts as a maximum (such as the MC33269 from ON Semiconductor that is installed on most genuine Arduinos), some models have a 15 volts restriction (such as the AMS1117 5.0 found on most Nano clones), but almost never less (one exception I found is Torex XB1117 that has a rating of 10 volts, but you won’t see it on a Duino board, genuine or not).
However, if you check the specs of a voltage regulator onboard your Arduino (it’s a variation of a 1117 5v regulator) you’ll see that it is perfectly capable of dealing with 12 volts. Considering that a LED strip power supply usually provides a bit more than nominal 12 volts (something like 12.3 in fact), you may be tempted to avoid connecting it to Arduino. Most Arduinos have a Vin pin that can be connected to bigger voltages, with 9 volts recommended and 12 volts a safe maximum that, according to some, should be generally avoided. LED strip is usually run off 12 volts, Arduino works on 5 volts.
Before we start connecting the Arduino to a LED strip, let’s deal with the power source.
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