Mail Archives: geda-user/2015/07/21/15:03:00

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Date: Tue, 21 Jul 2015 14:02:41 -0500
From: John Griessen <john AT ecosensory DOT com>
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To: geda-user AT delorie DOT com
Subject: Re: [geda-user] [OT] I need help with selecting components
References: <1507211704 DOT AA02900 AT ivan DOT Harhan DOT ORG>
In-Reply-To: <1507211704.AA02900@ivan.Harhan.ORG>
Reply-To: geda-user AT delorie DOT com

On 07/21/2015 12:04 PM, Spacefalcon the Outlaw wrote:
> I don't really know to be honest, but those are
>     the figures I've seen stated in some places as to how much DC a
>     cellphone Tx power amplifier can draw.

To estimate your system power draw, you can take the 2.5A at ?what? voltage
the spec you read says for a starting point.  Then if you use a DC-
DC buck regulator, figure the volts X amps from above plus power supply inefficiency
to get the likely power draw.  Then calculate for various supply voltages.

If you only have a linear regulator to get from 5.5V to whatever your system chips use,
then it all will go into heat and it WILL be 5.5 X 2.5 = 13.75 Watts.

I'd buy those wall wart barrel connectors in such case, since you will need
the >2.5A current spec. and they do it cheaply.  For the plugs you could simply salvage
from unwanted wall warts at first and have little or no soldering to do for that half.

On 07/21/2015 12:04 PM, Spacefalcon the Outlaw wrote:> recommendation for a pushbutton switch part
 >     that's appropriate for such an application?

Those switches that have a four leg solder attach with snap action 2mm button in the middle.  Try
Digikey, Mouser...or take them off some junk.   (I can mail you some...)

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