I'm building a DC power supply with a 36V DC supply module that needs a 12V fan. I'm using a buck converter, but accidentally bought a 24V max input rated converter instead of a 36V.. What's the most efficient way to step this voltage down so I can use the buck converter I bought?

 

Can you return it and order the correct converter?

 

Welcome to AAC!

What's the most efficient way to step this voltage down so I can use the buck converter I bought?

Another buck converter.

Instead of using two buck converters, just get one that will convert 36V to 12V. Two converters will be less efficient than one.

 

Take two fans in series - or change the fan to a 24v Type , may be this is cheaper than th converter

 

For just $6, all your problems will be solved and solved for the next 5 projects.
https://www.amazon.com/10pcs-Mini36...t=&hvlocphy=9006270&hvtargid=pla-797802734602

 

@sandeky5 Don't get your hopes up. The regulators mentioned in #5 have a maximum input voltage of 23V; a bit shy of your 36V requirement.

 

Sorry, wrong one. Try these. $9.99 for 6. 3v to 40v input. 1.5v to 35v out with adjustment pot.

https://www.amazon.com/MCIGICM-step...dp/B06XZ1DKF2/ref=psdc_10967761_t3_B07T7L51ZW

 

Sorry, wrong one. Try these. $9.99 for 6. 3v to 40v input. 1.5v to 35v out with adjustment pot.

https://www.amazon.com/MCIGICM-step...dp/B06XZ1DKF2/ref=psdc_10967761_t3_B07T7L51ZW

The ONE thing that concerns me is the 35V cap at the output. This is rated to receive up to 40V and output up to 35V. Because this is so close it concerns me. I know you want to operate it at a lower output voltage, and it may be OK. But then again, this design and spec parameters concerns me. What kind of engineer would leave him(or her)self no head room on the output? Makes me suspicious of the whole thing. But hey! You may get lucky and get some good ones. After all, there are over 170 reviews giving it 4 1/2 stars. Just might be OK. I'm going to read some of the negative reviews just to see what you might be dealing with.

[edit] Eh, after reading some of the reviews I don't think I would buy them. But that's ME. The old adages are true: You get what you pay for - and Buyer beware.
[end edit]

 

Those work fine for what they are... if you're dropping to 12V not even close to 35V so go for it. I have a bunch of them just in case I need something for a quick project. The 3A output rating is bogus, but should be fine for one computer fan.