Message-ID: <55CCA9F5.10708@posteo.de>
Date: Thu, 13 Aug 2015 16:30:13 +0200
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <8D2A262E5AABBD8-1F8C-27C7C0@webmail-vm073.sysops.aol.com> <55CB0509.80606@tele2.se> <4E61B79C-1D1C-44E7-872E-A1D53744A657@hurontel.on.ca> <55CC58A4.7070706@tele2.se>
In-Reply-To: <55CC58A4.7070706@tele2.se>
Subject: LF: 5V DC/DC modules for LF/MF
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Hi all,

My remote MF system is down at the moment, for doing some upgrades and 
improvements.

I'm replacing a DC/DC converter which supplies the Raspi with a constant 
5V voltage.

So far i used a *LM2596 module*, available e.g. at amazon
It was running well with almost no QRM to the RX. It's fixed switching 
frequency is at *150 kHz*. That's a bit close to LF and the 3rd harmonic 
is close to MF! I sometimes saw a weak drifting trace on MF.

Now the new one is a *Kis-3r33s module*, also available at amazon. This 
one is running at* 333 kHz*, far away from LF and MF, also it's harmonics.

The main aspect is the efficiency though! I defined a power saving mode 
(5V*89mA) and a full power mode (5V*430mA) for the Raspi. Normally the 
system runs at full power 24/7.

The LM2596 module has 77.8% efficiency in power saving mode and 78.5% in 
full power mode.
The Kis-3r33s module has 83.9% efficiency in power saving mode and_ 
*89.9%*_ in full power mode!

By exchanging this module, is can save 57 mA on the 12V-battery side!!! 
:-) This is about 1.4 Ah or 17 Wh per day, which is a LOT for a solar 
powered system. So the remote MF system is now consuming *2.4 W* 
permanently.

Just to share this measurement in case someone of you is running a 
similar system.

73, Stefan

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Hi all, <br>
<br>
My remote MF system is down at the moment, for doing some upgrades and
improvements.<br>
<br>
I'm replacing a DC/DC converter which supplies the Raspi with a
constant 5V voltage. <br>
<br>
So far i used a <b>LM2596 module</b>, available e.g. at amazon<br>
It was running well with almost no QRM to the RX. It's fixed switching
frequency is at <b>150 kHz</b>. That's a bit close to LF and the 3rd
harmonic is close to MF! I sometimes saw a weak drifting trace on MF.<br>
<br>
Now the new one is a <b>Kis-3r33s module</b>, also available at
amazon. This one is running at<b> 333 kHz</b>, far away from LF and MF,
also it's harmonics.<br>
<br>
The main aspect is the efficiency though! I defined a power saving mode
(5V*89mA) and a full power mode (5V*430mA) for the Raspi. Normally the
system runs at full power 24/7.<br>
<br>
The LM2596 module has 77.8% efficiency in power saving mode and 78.5%
in full power mode.<br>
The Kis-3r33s module has 83.9% efficiency in power saving mode and<u> <b>89.9%</b></u>
in full power mode!<br>
<br>
By exchanging this module, is can save 57 mA on the 12V-battery side!!!
:-) This is about 1.4 Ah or 17 Wh per day, which is a LOT for a solar
powered system. So the remote MF system is now consuming <b>2.4 W</b>
permanently.<br>
<br>
Just to share this measurement in case someone of you is running a
similar system.<br>
<br>
73, Stefan<br>
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