[Elecraft] OT: Quiet 12V-to-5V converter

[Jeff Cochrane - VK4BOF]

Hi John,
What about using a 7805 regulator to drop the 12V to 5V?
I'm sure that you could do the job with one of those and maybe a coupla 
small caps for bypassing.
Heatsinking, if any would need to be minimal for the regulator.
And no noise issues, if the bypassing is done right.

HTH

73 de
Jeff Cochrane - VK4BOF
East Innisfail
QLD, Australia
K3 #4257, P3 #1629, KPA-500 #161

----- Original Message ----- 
From: "John Gibson" <gibson at alma.edu>
To: <elecraft at mailman.qth.net>
Sent: Saturday, January 07, 2012 1:10 AM
Subject: [Elecraft] OT: Quiet 12V-to-5V converter


> Dear Elecraft list members,
>
> The recent thread on noisy switching power supplies leads me to a related 
> question. My son n8fyk, who teaches radio astronomy, has set up a project 
> with his students. They are using a 15m direct-conversion Radio Jove 
> receiver in the field to monitor radio emissions from Jupiter, the sun, 
> and the galaxy. The receiver operates from 12V, which is readily supplied 
> by a portable utility 12V battery pack. Their problem is powering their 
> data recorder, which needs about 5V at 0.7A.
>
> The data recorder is designed to operate from three internal AA alkaline 
> cells, but these give a limited run time. My son would like to be able to 
> leave the receiver and recorder for unattended operation for several days 
> at a time.
>
> One solution would be to use a 12V-to-5V power converter between the 12V 
> battery and the data recorder. For long battery life, it would be nice to 
> have the efficiency of a switching converter. Such a converter would have 
> to be RF-quiet, so as not to interfere with their weak-signal reception.
>
> I will be interested to hear what list members recommend.
>
> Thank you and 73,
>
> John, no8v
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