user20381: I have 2 LED strips with 6 LEDs on each. They use a 12V power supply.
My question, how can I use them like regular LEDs using Arduino UNO? Without any MOSFETS or transistors if possible.  
And can I use PWM?

user23841: It's not safe for the MCU without transistors or so.
You can use some kind of LED driver (for example TLC5940 with on chip PWM) or ULN2003 as 8 channel low side switch (instead of 8 transistors, PWM is possible if you do it programmatically) or many others.
With single transistor it looks like:

Where R_1 can be about 1K and transistor can be any NPN that could handle led current.

20381: <p>I have 2 LED strips with 6 LEDs on each. They use a 12V power supply.</p>

<p>My question, how can I use them like regular LEDs using Arduino UNO? Without any MOSFETS or transistors if possible.  </p>

<p>And can I use PWM?</p>
 23841: <p>It's not safe for the MCU without transistors or so.</p>

<p>You can use some kind of LED driver (for example TLC5940 with on chip PWM) or ULN2003 as 8 channel low side switch (instead of 8 transistors, PWM is possible if you do it programmatically) or many others.</p>

<p>With single transistor it looks like:
<a href="https://i.stack.imgur.com/ycp0m.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ycp0m.jpg" alt="enter image description here"></a></p>

<p>Where R_1 can be about 1K and transistor can be any NPN that could handle led current.</p>
