[hpsdr] PicoPSU power supplies

[n3evl]

Sounds like you'd have been better off with the PicoPSU-120-WI-25 
converter whichaccepts 12 - 25V input.  I'm using one of these with my 
HPSDR equipment and supplying it with the usual 13.8V from a bench top PSU

Pete, N3EVL



On 2/4/2012 2:48 PM, John Ackermann N8UR wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Sorry for the cross-post, but I know this is of interest to some folks 
> on the HPSDR (high performance software defined radio) list, and I 
> suspect it may be helpful for some time-nuts as well.
>
> The important message first: the little "PicoPSU" switching power 
> supplies that plug directly into an ATX socket say they are for 12V 
> input.  It turns out that they mean it -- the supply will shut down if 
> the input voltage is more than 13 - 13.5 volts.  So using these in a 
> typical battery-powered environment is potentially a problem unless 
> you somehow drop a volt or so.
>
> Here's the sad story...
>
> I recently built several low power Atom-based computers that use the 
> PicoPSU supplies.  The theory was that I'd run these machines, along 
> with all the other 12V gear in the basement, off a couple of big 
> batteries on a float charger.  The battery voltage varies from about 
> 13.5 to 14.2 depending on the charger state.
>
> Built the machine on the bench using an Astron supply, and everything 
> was cool.  Put on the battery bus in the lab, and things got very 
> funky.  Sometimes the power LED would come on, but nothing more would 
> happen.  Take the machine to the bench, everything was fine.  Take it 
> the lab, didn't work.
>
> I checked all the power connections and found no problems, but the 
> battery supply simply would not run the computer.
>
> Finally, I found a manual for the PicoPSU on the web, and discovered 
> that when they say it's a 12V supply, they mean it -- there is an 
> overvoltage shutdown that's supposed to trip between 13.0 and 13.5 
> volts.  In practice, it seems that at least some of them are good for 
> a little bit more than that, because the 13.8V from my bench supply 
> worked OK.  But when the battery voltage hit about 14.1, that was too 
> much and the supply shut down.
>
> So, I now have the computers running from an Astron supply that I 
> adjusted for good measure down to 12.6 volts, and all is well.  For 
> the long term, I'm considering putting a diode or two in series with 
> each computer's power lead to drop the voltage that way.
>
> John
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