Re: [Raspberry_Pi_4-Ham_RADIO] Re: Powering the Raspberry & TNC.
- you just have to watch switchers as they can cause birdies depending on where the switching freq. is.I have a large 20A PSU I use to power my radios, but it has an adjustment so you can move the birdie out of band if you happen to notice it in the part of that band you are working.B
From: Charles <k4gbb1@...>
Sent: Monday, April 1, 2013 10:24:46 PM
Subject: [Raspberry_Pi_4-Ham_RADIO] Re: Powering the Raspberry & TNC.
Yes, it is a switching PSU. I have had others make the same remark about avoiding the Use of a Switching PSU.
The Voltage is Very Stable... even with the added load of a TNC-Pi.
The module is rated at 1.5 A so that should be more than enough to give reliable power. I am using the RPi as a Packet server. The apps are an FPAC node and the Linux RMS Gate.
The system has been in constant service since late Jul 2012.
--- In Raspberry_Pi_4-Ham_RADIO@yahoogroups.com, "siegfried jackstien" <siegfried.jackstien@...> wrote:
> It is a switcher ... right?
> So when you plan to use the raspi as a server for rtl stick or similar
> things then I would try to avoid switching psu
> Ps maybe ok with some added filtering?
> > -----Ursprüngliche Nachricht-----
> > Von: Raspberry_Pi_4-Ham_RADIO@yahoogroups.com [mailto:Raspberry_Pi_4-
> > Ham_RADIO@yahoogroups.com] Im Auftrag von Charles
> > Gesendet: Montag, 1. April 2013 18:16
> > An: Raspberry_Pi_4-Ham_RADIO@yahoogroups.com
> > Betreff: [Raspberry_Pi_4-Ham_RADIO] Powering the Raspberry & TNC.
> > For those who plan to power the Raspberry, TNC and radio package from a
> > 12VDC source.....
> > Here is the DC to DC converter that I have been using since July of last
> > year w/o an problems. The 1.5 A output is more than enough to supply the
> > TNC-Pi and Raspberry.
> > This little inexpensive device was $4.30 plus shipping:
> > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=811-2196-
> > 5-ND
> > <<Charley>>
> > k4gbb
Most computer mother boards have switch mode regulators on the board to make all the various
voltages needed for the processor(s), memory, north & south bridges, and various other hardware.
Gamer & enthusiasts boards often tout how many regulators/phases they have.
As for radiation, most of the noise is from the leads & tracks on the board of chips themselves,
especially when they are unshielded. A 5, 3.3, or even 1.8 volt signal toggling on-off at a high
rate can radiate quite a bit, with 32 or 64 bits wide all toggling at such high clock rates it will
radiate a lot of hash.... Computers tend to generate & radiate a lot of hash that's one reason the
better made ones have metal cases and metal shielding in key areas. The minor amount of noise/ripple
out of the supply is miniscule compared to the hash from the computer it-self. If a supply is truly
that noisy the noise/spikes on the power would be mistaken for data and foul up the processing.
-Jim- N1JMM, KB1YPL_B
Visit my Pi running ircddb, dvrptr, Apache & many other things:
On 4/7/13 6:15 AM, JJ wrote:
> On 13-04-07 05:49 AM, John B. Cundiff Jr. wrote:
>> Every time any digital device switches from off to on it produces a small spike and every spike
>> as harmonics or RFI ... you can never completely clean up the supply of a computer ...you must
>> design the computer
>> to live with the spikes and RFI.
>> On 04/07/13, Ray Wells<vk2tv@...> wrote:
>> It's more than just spikes.
>> The National Semiconductor recommendation to "tame" the output of the LM2596 smps is to add a
>> series inductor (10mH from memory) and a shunt capacitor. Whilst this may very well result in a
>> power supply that will "please" the Pi, it will do absolutely nothing to suppress RFI, which
>> requires techniques quite different from those that produce a clean DC supply. The problem is not
>> insurmountable but would require some devotion to produce a supply that is both DC and RF clean.
>> It can be done.
>> FWIW, the problem, from a Pi perspective, isn't necessarily spikes. Some smps's produce a distinct
>> sawtooth output under load and whilst there may not be any spikes, there may well be dips below
>> the minimum working voltage of the Pi at the bottom of the sawtooth waveform.
>> Don't believe for one moment that you can assess a supply as being "good" with a voltmeter,
>> digital or otherwise. It is indeed a case where a picture is worth a thousand words and that is
>> where the CRO plays its part. If you don't have a hardware CRO, use a soundcard based device.
>> There is plenty of free oscilloscope software available online.
>> Ray vk2tv
>> On 07/04/13 18:03, John B. Cundiff Jr. wrote:
>>> Wood not a simple choke ...maybe a torridal choke
>>> suppress the spikes every one is worried about .
>>> Put a big value filter capacitor afterwards .
>>> Be a lot more portable .. simpler and ..eleganter etc.
>>> On 04/06/13, Kerry McKenzie<kermck@...> wrote:
>>> a rarely dumb question?
>>> how hard is it to just get an old pc power supply AT or ATX ,.... who
>>> cares either way,... you will get between 15 and 50 amps at 5 volts and
>>> throw a couple of caps across it.
>>> If you crow it,... it will be smooth
>>> if you go to any computer repair shop they will possible give you as
>>> many old ones as you want as most of them still work.
>>> i have 4 or 5 in my workshop down stairs and use them for all sorts of
>>> things and it so easy.
>>> my 2 cents worth.....Kerry
>>> PS Linux is still a bitch and I,m going nowhere with my projects ;-((
>>> Kind Regards
>>> Kerry McKenzie
>>> PO Box 4492
>>> Kirwan QLD 4817
> yes, I agree...I use a vp-1020 satellite card in my computer and the P.S. noise is affecting the
> sensitivity of the card....my ham antennas are more than 100 feet from the house due to the rf
> racket produced by many switching power supplies in the house...even the darn router and cable modem
> supplies were awful, so running as much as I can directly from my solar system 12v rail...but there
> are just so many things nowadays that use these switching supplies it's hard to eliminate them
> all...oh, and then there's a neighbors samsung plasma tv .. 300 feet away from here and it wipes out
> my packet system when it's on...