[Lowfer] A power supply head scratcher

Sat Apr 17 23:32:24 EDT 2010

Hi Gentlemen:

As usual, a wrong choice of words on my part. I tied the positve wire
of one wart to the negative wire of the other one. The remaining 
positive , and negative wires went to the circuit. At this point, I am
just about ready to sling these thing as far into the pond next door 
as I can throw them. In all my years. I have never had a power supply
to do such crazy things. BUT !!! I must state that I have never tried
to use these stinkin little SMPS wall warts either. Always used analog
supplies before. But you don't find 30+ volts DC in an off the shelf
store bought power supply. The best thing I could do now is to just
build myself a good analog supply with a 24 volt transformer. That
should approach the 30 volt output when filtered, and then run it into
my adjustable regulator board to get the 25 volts I need, or very close
to it at least.

To note for the record:  Thanks to everyone for the tips offered.
I have tried all of them. .1 caps everywhere I could fit one, reverse
biased diodes, load resistors across the output. even tried the
paralled diode, resistor, capacitor trick. Nothing will stop the spikes
from killing the beacon.  *** There is a better than not chance that the
wall wart is bad. Could be why I found it in a junk box of parts at the
local flea market.

Andy - KU4XR - EM75xr - Friendsville, TN. USA
LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
Coordinates:  N:  35º 43' 54" - W:  84º 3' 16"
http://www.myspace.com/beaconxr
http://webpages.charter.net/ku4xr/

--- On Sat, 4/17/10, Jordan <outposter30 at shaw.ca> wrote:

> From: Jordan <outposter30 at shaw.ca>
> Subject: Re: [Lowfer] A power supply head scratcher
> To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" <lowfer at mailman.qth.net>
> Date: Saturday, April 17, 2010, 8:47 PM
> You're going to start a fire....
> 
> 
> ----- Original Message ----- 
> From: "Bill Ashlock" <ashlockw at hotmail.com>
> To: <lowfer at mailman.qth.net>
> Sent: Saturday, April 17, 2010 5:27 PM
> Subject: Re: [Lowfer] A power supply head scratcher
> 
> 
> 
> "I simply connected them 10 volt positive open, and the
> negative
>  connected to the 24 volt positive, with the negative
> open."
> 
> Hi Andy,
> 
> Am I correct in my thinking that you have not connected
> anything to one of 
> the two output wires of each wallwart? If so, I don't
> understand why this 
> works at all unless there is some kind of sneak path to the
> neutral line in 
> each power supply. Why not connect them in series as though
> they are 
> batteries? These wallwarts have a power transformer that
> should isolate the 
> DC output from their AC power inputs and this DC should
> float relative to 
> anything else.
> 
> Bill
> 
> > Date: Fri, 16 Apr 2010 20:38:58 -0700
> > From: ku4xr at yahoo.com
> > To: lowfer at mailman.qth.net;
> part15 at yahoogroups.com
> > Subject: [Lowfer] A power supply head scratcher
> >
> > First, Thanks for all the responses to the antenna
> insulator question.
> > J.B. had the one i'd never of thought up, The broken
> pole vault pole.
> >
> > I do have a head scratcher here. To get around 35
> volts DC, I have
> > connected 2 wallwarts in series. One is a 10 volt, and
> the other,
> > a 24 volt. Connected together I have 37 volts DC. ***
> This is the first
> > time I have ever tried this method before, so I have
> no previous
> > experience to go by. I simply connected them 10 volt
> positive open, and
> > the negative connected to the 24 volt positive, with
> the negative open.
> > The problem I'm having is that everytime something in
> the house turns
> > OFF, it kicks off the beacon....hmmmm. AC goes off,
> and so does the
> > beacon, fan in the room goes off, beacon does too.
> connect the HF ant.
> > to the radio and it kicks the beacon off. I have
> filtered the hound out
> > of it. But can't stop this problem. It seems to be
> coming in on the
> > ground line. These 2 wallwarts were 2 pronged plugs,
> and would not work
> > the circuit until I connected a 3 prong plug with the
> ground wire going
> > to the DC negative wire. The warts are SMPS. Even
> though I have the
> > voltage I want, something is amiss. It is getting
> spiked somehow.
> > Has anyone tried this before, and had a similar
> experience ?? If so,
> > were you able to fix it, and how did you do it ?? I
> may have something
> > wired the wrong way, or maybe missing a capacitor
> where one should be.
> > I don't have a schematic for a circuit like this, and
> can't find one
> > on the net. I'm wondering if I have a floating ground
> issue between the
> > 2 wallwarts.
> > Any input will be appreciated, and thanks for your
> time.
> >
> > 73 everyone :::
> >
> >
> > Andy - KU4XR - EM75xr - Friendsville, TN. USA
> > LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
> > Coordinates:  N:  35º 43' 54" - W: 
> 84º 3' 16"
> > http://www.myspace.com/beaconxr
> > http://webpages.charter.net/ku4xr/
> >
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