user14424: I'm trying to dim a 10w LED via Arduino PWM.
This is the LED that I have: http://www.banggood.com/10W-Warm-Pure-White-High-Brightest-Save-Power-LED-Light-Lamp-p-88169.html
Without knowing much about this stuff, I bought this (namely because it had LED, DIM, and PWM in its name): http://www.ebay.com.au/itm/121437119430?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
I can't get the eBay dimmer to work for love or money.  When I connect it to ground directly on the battery terminal, it goes off, which means the dimmer circuit is working.  I don't even know where to start with MOSFET dimming solution, but I think that the IRFZ44N MOSFETs are the wrong ones because they won't turn on with 5v power (they need 10v or something, but those are the ones I have on hand).
I can't seem to find any good guides on how to do this after stacks of googling, and to be honest, I don't even know if those LED's can be dimmed in the first place.
What do I need to make this happen?

user10214: Well, it appears that your driver should do that for you. Since you already have the MBI6651 driver, read its datasheet and so you can get a guess on how it should work:

attach a 9-35V supply to the Vin-GND terminals. I suggest to use at least 12V
attach the LED to the terminals LED+ and LED- (remember the polarity!)
attach a transistor to pull down the pin DIM
send a PWM signal (frequency between 100Hz and 1000Hz) to the transistor and you should see the LED light up and then dim

If it works then you can try to send to DIM directly th PWM signal, but personally I don't recommend so (unless the board already have the transistor)
EDIT:
How to attach an nMOS to the DIM pin. Since the pin is internally pulled up, you don't need any pullup. So you just need an nMOS. I suggest you to use a SOT-23 logic level nMOS connected this way:

no external components (as long as the nMOS supports 5V on the gate, but every discrete mosfet should). As for the nMOS, I prefer the SMD case because it is easy to solder also on perfboards (just use three pads forming an L shape and you'll see that you can easily solder it). Just choose any n-channel mosfet with a maximum threshold voltage of 2V or less and you are done

14424: <p>I'm trying to dim a 10w LED via Arduino PWM.</p>

<p>This is the LED that I have: <a href="http://www.banggood.com/10W-Warm-Pure-White-High-Brightest-Save-Power-LED-Light-Lamp-p-88169.html" rel="nofollow">http://www.banggood.com/10W-Warm-Pure-White-High-Brightest-Save-Power-LED-Light-Lamp-p-88169.html</a></p>

<p>Without knowing much about this stuff, I bought this (namely because it had LED, DIM, and PWM in its name): <a href="http://www.ebay.com.au/itm/121437119430?_trksid=p2057872.m2749.l2649&amp;ssPageName=STRK%3AMEBIDX%3AIT" rel="nofollow">http://www.ebay.com.au/itm/121437119430?_trksid=p2057872.m2749.l2649&amp;ssPageName=STRK%3AMEBIDX%3AIT</a></p>

<p>I can't get the eBay dimmer to work for love or money.  When I connect it to ground directly on the battery terminal, it goes off, which means the dimmer circuit is working.  I don't even know where to start with MOSFET dimming solution, but I think that the IRFZ44N MOSFETs are the wrong ones because they won't turn on with 5v power (they need 10v or something, but those are the ones I have on hand).</p>

<p>I can't seem to find any good guides on how to do this after stacks of googling, and to be honest, I don't even know if those LED's can be dimmed in the first place.</p>

<p>What do I need to make this happen?</p>
 10214: <p>Well, it appears that your driver should do that for you. Since you already have the MBI6651 driver, read <a href="http://www.ledlabs.ru/pdf/macroblock/mbi6651.pdf" rel="nofollow noreferrer">its datasheet</a> and so you can get a guess on how it should work:</p>

<ol>
<li>attach a 9-35V supply to the Vin-GND terminals. I suggest to use at least 12V</li>
<li>attach the LED to the terminals LED+ and LED- (remember the polarity!)</li>
<li>attach a transistor to pull down the pin DIM</li>
<li>send a PWM signal (frequency between 100Hz and 1000Hz) to the transistor and you should see the LED light up and then dim</li>
</ol>

<p>If it works then you can try to send to DIM directly th PWM signal, but personally I don't recommend so (unless the board already have the transistor)</p>

<p>EDIT:</p>

<p>How to attach an nMOS to the DIM pin. Since the pin is internally pulled up, you don't need any pullup. So you just need an nMOS. I suggest you to use a SOT-23 logic level nMOS connected this way:</p>

<p><a href="https://i.stack.imgur.com/Myxdh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Myxdh.png" alt="nMOS connection"></a></p>

<p>no external components (as long as the nMOS supports 5V on the gate, but every discrete mosfet should). As for the nMOS, I prefer the SMD case because it is easy to solder also on perfboards (just use three pads forming an L shape and you'll see that you can easily solder it). Just choose any n-channel mosfet with a maximum threshold voltage of 2V or less and you are done</p>
