10-04-2016, 06:26 PM
(10-04-2016, 08:35 AM)MarkHaysHarris777 Wrote:(10-04-2016, 07:14 AM)dkryder Wrote: the atx power supply is a good bench power source. many small electronics shops have used units for 5 to 10 dollars [u.s.]
The trouble with atx power supplies is that they often have a substantial minimum current draw (can be as high as 3-5 amps) or they don't work properly. A fully loaded Pine board would be on the low side of that. The reason for this is that most atx power supplies are switching supplies capable of delivering 5.1 volts regulated at fifteen or more amps -- so they are optimized for the expected high current draw... a low current load like the Pine board may not be adequate to meet the minimum current specs of the atx supply. Most of the time folks that use atx supplies for bench supplies need to fabricate and minimum dummy load -- and of course that can be done in the case of the pine board too.
Yeah, the problem is usually that the power supply is designed to have a minimum load in order for it to stay on, thus the need for a dummy load for standy/light loads. However, that is more an issue with newer ones. I have a couple of older ones from pre ATX12V standard changes, and they don't need any minimum load. It does make me wonder why Sparkfun never put a load resistor on their breakout board, which is why the Mystic ATX PS Adapter is a much more reliable option if you wanted to fiddle in that space. There are server grade PSUs lke the HP DPS-600PB that a lot of hobbyists get second-hand and use for high current 12v power sources (but also have 5v rails), and don't need any tinkering with to stay on or anything. But they aren't as cheap, and are plain overkill for the pine64, unless you want to make a mega cluster
