[arm-allstar] 12V to 5V DC-DC Converters?

[Sam Skolfield]

David/ Everyone,
Which switching DC-DC converter should I be using for my BBB? I Have a URI
and four USB-Serial adapters connected, so I'd like to come up with an
adequate power supply.

Thanks and 73

Sam Skolfield
KJ6QFS

On Thu, Nov 20, 2014 at 8:41 PM, David McGough <kb4fxc at inttek.net> wrote:

>
> Hi Tom,
>
> Thanks for sharing your schematic. I've noticed one area of concern, which
> has personally bit me before. You should add a capacitor (perhaps 1uF or
> larger) very near the input of the LM7806. These little regulators are
> wonderful except when they decide to oscillate. And, that can happen, I
> promise--(Hind sight: 20/20 in my case!). Even if your regulator is well
> behaved, others might encounter problems if they try to duplicate your
> design, due to subtle variations.
>
> Also, note that the TIP110 transistor is rated for a maximum base-emitter
> voltage of 2.8VDC. So, your results many vary from device to device.
> Under variable load, the voltage regulation probably won't be perfect.
>
> A simpler linear regulator would be to use an LM7805T directly (including
> input and output bypass capacitors). They're capable of at least 1A output
> directly and will power a BBB okay...They will need a heatsink with a 12v
> input source.
>
> The primary reason I bring all this up is that BBB's are VERY sensitive to
> any power supply instability. The best, inexpensive, solution I've found
> is a small switching DC-DC converter like those already mentioned.
>
>
> 73, David KB4FXC
>
>
>
> On Thu, 20 Nov 2014, k5tra wrote:
>
> > 'Looks like the attachment didn't make it onto the list. Here's a link:
> >
> >
> >
> >
> https://dl.dropboxusercontent.com/u/97484437/BBB%20Regulator%20%26%20Fan%20C
> > ontrol.jpg
> >
> >
> >
> > Tom / K5TRA
> >
> >
>
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>



-- 
KJ6QFS
Sam Skolfield
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