Source for regulator/buck used in J1Sys Boards

[Wolfie]

Does anyone have a line on where to buy the 5v regulator/buck that he uses on most of his boards?

Its this little beastie I am looking for:
[attachimg=1]

No, I didn't burn one. I want more for some other projects to I derive 5v from 12v pixel feeds.

 

[David_AVD]

You can get them from Digikey or Mouser (both in the USA). Part number is OKI-78SR-5/1.5-W36-C

 

[pagrosse]

You can also get 3amp ones a bit larger in size for around a 1$ each on eBay shipped. Search for buck converter. I use them on my 5v pixels. Plus u can sent them to any voltage. I set mine at 5.5-5.7v

 

[David_AVD]

Just remember that the eBay DC-DC converters often use counterfeit parts and often fail to meet the claimed specs.

That said, I sometimes use them for non-critical applications and never near their rated max specs.

 

[Wolfie]

Thank you for the part #s! I will hit mauser tomorrow.

I want them to power Max485 chips so I don't have to send 12v and 5v as well as the twisted data pair down the wire to the pixels. Almost no current so the tiny ones will suffice. I won't be driving pixels with them if thats what yall were thinking.

 

[David_AVD]

You could use a standard 7805T regulator with a couple of capacitors instead of the OKI if you're only powering the MAX chip.

 

[Wolfie]

Aren't they fairly inefficient compared to these buck types? I don't want to waste pixel power on inefficient regulators that turn 12v into heat.

 

[multicast]

Aren't they fairly inefficient compared to these buck types? I don't want to waste pixel power on inefficient regulators that turn 12v into heat.

you said it was tiny current. So the amount of power you are talking about wasting is going to be small.

 

[Wolfie]

Yes. But I thought they wasted quite a bit of power doing what they do, even for low current applications. Typical use also requires (or at least recommends) use of filter caps which makes its footprint actually physically larger than the tiny buck converter.

So the buck consumes less power, makes less heat, and is smaller.

These are going to be used away from a PSU at the end of a cable run. I don't want to loose any more pixel power than I have to which is why I was looking for the buck.

 

[multicast]

Yes. But I thought they wasted quite a bit of power doing what they do, even for low current applications.

They are a linear device. The amount of energy lost is directly proportional to the current and the voltage differnece between input and output.


If you put in 12V into a 7805 then the Voltage drop across it is 7V. Multipy that by the the current that your device will draw and thats the amount of power it will dissiipate.


Examples;


(12-5) * 10mA = .07W ( quite accetable )
[SIZE=78%](12-5) * 1A = 7W ( its going to get very hot without cooling it and waste lots of power[/SIZE]




A buck regulator may be more efficent at its rated power, ( say 1A output ) but the tiny powers yuo are talking about, it likely to be less effienct. A buck requires some power for itself to run as well, which may be greater than the loss's that a linear regular would present.


Its all about your applicaiton. A buck does not always present the best option

Typical use also requires (or at least recommends) use of filter caps which makes its footprint actually physically larger than the tiny buck converter.

Buck regulators also need caps. Some of the "on board" types will have the caps built in, but some requrie you ti provide inout and output caps as well.

So the buck consumes less power, makes less heat, and is smaller.

In some circumstances, but not in all.

 

[Wolfie]

It is linear isn't it. Doh! I think it still takes more space with the extra caps than the buck.