Duel Buck Converters - Safe?

Please forgive my diagram, it's my first ever!

I'm hoping to power a small project from 12v, using a buck converter to drop the voltage for an Arduino Nano.

I also want to control the brightness of a 12V LED strip with another buck converter tied to one of the Arduino's PWM pins.

I feel like I have misunderstood something though - it can't be this straightforward!

I'd love to hear what those with more experience thought.

Can you please post a diagram that doesn't need a magnifying glass to read the pin labels? Doesn't have lines that blot out the labels?

Forgiveness is nice, but won't solve the problem...

You should also post some details and/or links to the buck converters.

If I’m looking at it correctly…
You can’t source the supply for anything from an Arduino pin… they are ‘signal’ only.

Agree that your drawing is little help, but it looks like you’re driving that lower module from Arduino pins - you probably shouldn’t do that.

It’s not clear what any of the blobs are, or are doing.
It often can be as simple as you hope, but unfortunately more detail and understanding is often needed to make that decision.

Thanks, guys. I can only read the labels with the image expanded myself too. I've tried to tidy it up, but am limited by experience. Hopefully a little clearer though.


12v DC

|--> buck converter 1 --> Arduino nano (vin&ground)
|--> buck converter 2 --> 12V LED strip

Buck1 is fixed for Arduino
Buck 2's PWM in is connected to Arduino pins D6 (PWM) & ground

If it's still too rubbish, I will have another crack at it tomorrow with fresh eyes.

I think my only question is what does that d- pin do on the LED controller?

Aside from the diagram that needs some help, I don't believe I see any issues other than that d- pin which goes back to the question.

You've got to start somewhere man! Glad to see you diving in. Sometimes things are that easy

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Third time lucky maybe...

Just another option/tip You should try to use schemeit for quick diagrams


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Looks interesting! I will give it a spin :blush:

Should be fine to wire up a Femtobuck LED driver this way.

If you're actually using a solderless breadboard you might want to add some bulk capacitance near each of the buck power connections.

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Let's revisit this request.

Buck 1: LM2596 DC-DC Buck Converter Adjustable Power Supply Step Down Module Multi | eBay
Buck 2: 6-30V 0-1.2A LED driver, PWM/Analog dim control, ready built or kit or bare PCB | eBay

It's different than what is in the Fritzing... isn't that worthy of some mention? The labels are different and there are only 3 terminals on the control side.

Also you called a LED controller, a "buck converter".

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It's my first use with any electronics diagramming software - so was just aiming for something rough to better explain my question rather than just dense text.

Fritzing only has those bucks as standard, but I think it gives you the jist. Hopefully!

The LED controller is a buck converter I think. just with PWM input where the pot was...

I'm going to ask you to produce an accurate schematic.

It's OK. If someone reading this has experience with this approach, I think they'll be able to understand enough from the diagram and accompanying text to help.

I don't want to create barriers to entry for myself on day 1!

Thanks though!

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You just did. You seriously confused two people already with the incorrect information, see reply #3 and #5...

You're right. I hope my diagram skills improve before my next question.

It isn't about amazing skills. It's just getting the idea across in a form that would better allow us to ponder the question, which is the most literally descriptive form... often a photo of a pen and paper sketch is the key, because you don't have to futz around with software and other distractions.

Sometimes, the key is posting photos of the hardware...

Oh, absolutely. You’ve convinced me.

There’s no hardware yet - I wanted to get some opinions first!

I’m grateful to the others for taking the time to respond to me, so I have the confidence to proceed now.

Thanks for all your input too, of course.