PWM driving of high-power LED with an arduino

Other Hardware LEDs and Multiplexing
1

I need to drive 2 red and 2 blue high-power LEDs for an application (LED indicated below).

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First of all, I connected the LEDs directly to the 12V power supply and measured the currents they draw.
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As you can see, the red one draws about 1.4A.
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As you can see, the blue one draws about 0.5A.
My question is that I want to use MOSFET to drive these LEDs with PWM, I have shared two circuits below which should I use?Why?
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Circuit-1
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Circuit-2

2

The second one.

It is simpler, adequate, and the 200 Ohm (actually 220 Ohm) resistor is the correct value. However there also should be a 10k resistor between the Arduino output and ground to positively switch the FET off while the Arduino is not powered or in the process of booting up.

But always use a Nano rather than a UNO for any "real world" project. I suspect you have already figured that out. :grinning:

3

But looking at the leds and seeing the huge difference in current I don't think they have any form of current regulation on them. So just connecting them to 12V is a bad idea... Better to use a proper driver (and thus more than 12V).

4

Thank you very much. I think the 10K resistance between the Arduino output and the ground meant this.Is this the scheme in the final?

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5

septillion:
But looking at the leds and seeing the huge difference in current I don't think they have any form of current regulation on them. So just connecting them to 12V is a bad idea... Better to use a proper driver (and thus more than 12V).

Can you suggest any circuit?

6

Multiple, but I think I would go for something like a switch mode IC designed for led driving. Not home so I can't mention a chip..

7

One important detail is to use the correct mosfet transistor, preferable a logic level type.
Check if the transistor gets warm, at these low current it must not heat up or you are using a wrong transistor type.

And be careful with buying mosfet on Ebay, they sell a lot of fakes.

8

LaCasaDePapel:
Thank you very much. I think the 10K resistance between the Arduino output and the ground meant this.Is this the scheme in the final?

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That image is apparently private to your account.

You had better give us the Web links to the LED strips you are using in order to avoid arguments about how to power them.

9

LaCasaDePapel:
I think the 10K resistance between the Arduino output and the ground meant this.

No, that just limits the inrush current on the gate of the FET, nothing to do with the LEDs.