-=> Maurice Kinal wrote to Tony Langdon <=-

 TL> If you don't need the speed, a Pi 2 is a good choice.

 MK> Speed is nice but if it isn't taking advantage of a 64 bit system then
 MK> it doesn't make much sense to me to spend the extra money.

Depends what you want.  I haven't found a need for 64 bit in anything I use a
Pi for.  Won't really be an issue until you start seeing more than 4 GB RAM, or
if you have an application that manipulates 64 bit variables.

 TL> I'm assuming that's the input voltage rating.

 MK> Yes.  It has 12VDC and 5VDC output but offhand I don't recall the
 MK> amperage.  In the case of the pi 3 it would need to be in the 2 amp or
 MK> better range to make it fully operational (mostly usb devices) from
 MK> what I've heard.  The board itself supposedly only draws around 500
 MK> milliamps at 5V.

Ahh, OK.  Yeah I've seen rating like 2.5A.  Yeah if you're not drawing much
from the USB ports, that will help heaps.

 TL> These days, I tend to go for switchmode converters

 MK> Those would be cheaper but then again I've already made the investment
 MK> ages ago on the DC/DC power supply which in it's day cost over
 MK> quadruple what the pi costs today.  I just have to make sure the 5VDC
 MK> amperage is high enough.

The biggest issue with linear supplies is (lack of) efficiency, which gets
worst as the input voltage increases.  In your example, efficiency at 7v input
can't around 75%.  At 32V input, it's more like 15%.  For me, that's a major
deal breaker.


... Failure is the path of least persistance.
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