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Wall warts

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  • Member since
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Saturday, March 7, 2020 4:43 PM

Like most people I keep anything that I might use later.  I also have a box full of wall warts (30 yrs) and very few are reusable, weird voltages or lack of current to be of any use.
 
I too standardized on 12 volt switching power supplies, high efficiency and less heat.  Like Mister Beasley said they are cheap and I haven’t had any problem the ones I have, several 10 years old.
 
The one big plus for a standard 12 volt DC source is the DC to DC converters.  I use my 12 volt high current switching power supply (30 amps $22) for all the accessories on my layout.  I operate all my 12 volt incandescent Grain of Wheat bulbs at reduced voltage (8½ VDC) for more realistic looking 1950s era lighting and greatly increased life using a DC to DC converter.  I haven't had a bulb burn out in over 10 years.
 
I also use 5 volts for Arduinos and LED lighting as well as 1.4 VDC for the 1mm 1½ volt micro bulbs in my HO vehicles.  All using the DC to DC converters.
 
This is my workbench power supply, a 12 volt 15 amp switching power supply with cheapo digital meters for monitoring the output from the two DC to DC converters mounted on top of the power supply.
 
 
This is an 8 amp DC to DC converter, adjustable voltage and current.  The converter measures 2½”L x 1¾”W x ⅞” H. (under $5)
 
 
I have found a good use for the 12 volt DC low current wall warts, I buy the cheapo digital panel voltmeters from China and they need an isolated 12 volts so as not to interfere with the device that is being metered, a 12 volt wall wart fills the bill.
 
The USB type wall wart is neat for powering an Arduino UNO project, my random lighting controllers draw about 1¼ amps at 5 volts full load.  
 
 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Saturday, March 7, 2020 3:59 PM

Some may be regulated output Most not regulated. Voltage with a meter will be usually higher until operated at rated current.

Some will say universal, 100- to 220 AC input what is called a switcher. Output many times is DC. Just read the label.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    April 2012
  • From: Huron, SD
  • 1,016 posts
Posted by Bayfield Transfer Railway on Saturday, March 7, 2020 3:57 PM

If you're one of us who has an old computer lying around, yank the power supply out of that.  They're actually halfway decent supplies.

 

Disclaimer:  This post may contain humor, sarcasm, and/or flatulence.

Michael Mornard

Bringing the North Woods to South Dakota!

  • Member since
    May 2010
  • From: SE. WI.
  • 8,253 posts
Posted by mbinsewi on Saturday, March 7, 2020 3:57 PM

When what ever the gadget was that the walwart came with, dies, I through out the walwart, along with the gadget. 

Mike.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 21,483 posts
Posted by MisterBeasley on Saturday, March 7, 2020 3:54 PM

I used to keep a box of old wall-warts for DC applications.  They had all sorts of odd voltages, and most could not provide much current.  They had no circuit breakers, so one good overload and it was toast.

I now get larger 12 volt, 4 or 5 amp supplies from China for a few dollars.  Yes, these also need a fuse, but they can power a lot of lights, and also my crossing signal circuits and with an extra dropping resistor, Miller Engineering signs, too.

Throw out the wall warts and standardize your electronics.  Fewer outlets for plugging in supplies will be needed.  As your layout grows, you'll be happier with this approach.

It takes an iron man to play with a toy iron horse. 

  • Member since
    September 2003
  • 21,669 posts
Posted by Overmod on Saturday, March 7, 2020 3:40 PM

ndbprr
Are they all the same output?

Not only are they not all the same output, some output AC and not DC.

As Mel and John indicated, you have to start by looking at any ratings printed on the case -- and there are two, not one, that are important to watch, once you've determined the output is DC and not AC.

One is the voltage -- this had better match what is on the DCC equipment you plan to connect, net of any voltage drop between the 'wart' and the device(s) it's intended to drive.  The second is the permissible amperage the device can source, presumably continuously (although it may involve no more than a particular allowable temperature rise in a certain time period, although this is seldom explicitly stated).  You should not even consider using a wart of less than the expected amp draw as given in the specs for the equipment you're driving.  (If necessary, you can get watts as the product of indicated amperage and volts, or derive permissible current from nominal 'watts' divided by voltage if that's what you're given. 

The plug on the wart almost certainly won't fit the DCC equipment you want to power.  Getting the DC polarity exact is a CRITICAL thing.  Use a meter; don't trust that the wiring 'looks' like it should be arranged with positive and negative conductors, or has stripes or colors on one side and not the other.

One potential caveat:  DO NOT attempt to power devices with an 'only slightly higher' nominal voltage wart, unless you've measured the voltage at the device connection point and found it comparable to what's expected.  Please do not ask me how I know that.

(Incidentally, many, many warts adhere to the USB power standard, which started out 5V at 1A and was then 'improved' to 5V at 2.1A (and then upward, to the 5.8A in some 'combination' chargers and then to the complicated logic-driven arrangements associated with type C connections).  You can use any such USB charger as a 5VDC supply at its stated power using little more than a compatible plug.  But test it first, as some of the cheap "Chinese" supplies have been known to short to live 120VAC without warning or even due to inadequate quality control when brand new...)

Oh, yes, and ALWAYS put a fuseholder and fuse in the positive line to the device.  And be sure that fuse is a correct type and rating for the wattage of the 'connected equipment' ...

  • Member since
    December 2010
  • From: Portland, Oregon
  • 658 posts
Posted by Attuvian on Saturday, March 7, 2020 3:31 PM

As Mel says, the output in both volts and milliamps will be labeled or cast on the body of the unit. They vary widely. Our clubs collects all sorts of them from members and other sources for DC applications (power to switch machines, signaling, building lighting, etc.) that are normally isolated from (DCC) track power. Just make sure your single or ganged load matches the output of the unit you're going to employ.  Voltage step-downs to these DC circuits may be appropriate or necessary.  Please consult with Mel or others on the forum that are true electrical gurus.

John

  • Member since
    January 2009
  • From: Bakersfield, CA 93308
  • 6,526 posts
Posted by RR_Mel on Saturday, March 7, 2020 3:22 PM

The voltage and current are on the bottom below the prongs that plug into the outlet.
 
 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
  • Member since
    September 2002
  • 7,486 posts
Wall warts
Posted by ndbprr on Saturday, March 7, 2020 3:18 PM

Are they all the same output? I have as many as 12 from phones even some from Palms. Can they be used to power dcc electronics?

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