Wall wart uses?


Richard Neil
 

I found an AC-DC wall wart in the garage.  It's 120V, 11W and output is 12V, 400mA.  It's from an old phone charger.  What can I use it for? Thanks for suggestions.
Richard


Blair
 

Richard

Get your voltmeter, set it to 20V range, and plug in the adapter in and measure the output with no load.  If it's a regulated supply, it will read 12V.  If it's not regulated, it may well be providing 16-20 volts, because the 12V, 400ma indicates what it will do with that much load; the output is higher at lower loads.

If it's regulated, you can use it for

- LED lights in buildings

- powering an Arduino, though 9V would be better.

- Powering a few Tortoises (30 ma per (or less), so up to 12 would be okay)

- any other small load application that comes along - there are lots of hobby devices that are 12V powered.

If it's NOT regulated, mark it clearly as such, and, I don't know, sequester it back in the garage?  I don't keep them around because sooner or later, someone will take the ratings plate literally.

Blair


On 2022-03-22 17:19, Richard Neil via groups.io wrote:

I found an AC-DC wall wart in the garage.  It's 120V, 11W and output is 12V, 400mA.  It's from an old phone charger.  What can I use it for? Thanks for suggestions.
Richard


Rich Randall
 

Power a bunch of LED lights in a town or industry area.

LEDs I have used work well at 20 mA.

Rich
Rich Randall
Gettysburg, PA

Modeling The Milwaukee Road
at Avery, ID, in O Scale

The BSME is now on facebook: 



-----Original Message-----
From: Richard Neil via groups.io <rneilphoto@...>
To: w4dccqa@groups.io
Sent: Tue, Mar 22, 2022 5:19 pm
Subject: [w4dccqa] Wall wart uses?

I found an AC-DC wall wart in the garage.  It's 120V, 11W and output is 12V, 400mA.  It's from an old phone charger.  What can I use it for? Thanks for suggestions.
Richard


Alexander Wood
 

Richard,

I have a whole pile of old wall warts, but I generally find that getting the right power supply for the right purpose ends up working better. That being said, there are plenty of uses for 12V on a model railroad, so you could see what it's putting out and see if you have a use for it.

Alex

On Tue, Mar 22, 2022 at 5:19 PM Richard Neil via groups.io <rneilphoto=aol.com@groups.io> wrote:
I found an AC-DC wall wart in the garage.  It's 120V, 11W and output is 12V, 400mA.  It's from an old phone charger.  What can I use it for? Thanks for suggestions.
Richard



--

Alexander Wood

Hartford-New Haven, CT

Modeling the modern era freelanced G&W Connecticut Northern in HO

Digikeijs DR5000 - TCS UWT-100 - Digitrax Simplex - ProtoThrottle - JMRI


Richard Neil
 

20 DCV = 14.75-14.95... use or not?
Thanks


-----Original Message-----
From: Blair <smithbr@...>
To: w4dccqa@groups.io
Sent: Tue, Mar 22, 2022 2:40 pm
Subject: Re: [w4dccqa] Wall wart uses?

Richard
Get your voltmeter, set it to 20V range, and plug in the adapter in and measure the output with no load.  If it's a regulated supply, it will read 12V.  If it's not regulated, it may well be providing 16-20 volts, because the 12V, 400ma indicates what it will do with that much load; the output is higher at lower loads.
If it's regulated, you can use it for
- LED lights in buildings
- powering an Arduino, though 9V would be better.
- Powering a few Tortoises (30 ma per (or less), so up to 12 would be okay)
- any other small load application that comes along - there are lots of hobby devices that are 12V powered.
If it's NOT regulated, mark it clearly as such, and, I don't know, sequester it back in the garage?  I don't keep them around because sooner or later, someone will take the ratings plate literally.
Blair

On 2022-03-22 17:19, Richard Neil via groups.io wrote:
I found an AC-DC wall wart in the garage.  It's 120V, 11W and output is 12V, 400mA.  It's from an old phone charger.  What can I use it for? Thanks for suggestions.
Richard


Bill Nelson
 

Can't it be used to power a DCC track layout? 


PennsyNut
 

BillN: Anything that is DC only!
Morgan Bilbo, DCC since 8/18. Model PRR 1952.


Don Vollrath
 

Any true “wall wart” where the ‘box’ plugs directly into the wall outlet is generally too small in watt and ampere rating to correctly power a DCC booster intended to operate a train. But you might find one with a 1 to 2 amp rating suitable to operate a booster dedicated to feed DCC to an accessory bus. Be sure to read the nameplate rating and know if the voltage output is regulated or not.

DonV


Steve Hubbard
 

I have 4 - 3 amp regulated 12VDC wall warts, so they are available.

 

Sent from Mail for Windows

 

From: Don Vollrath
Sent: Friday, March 25, 2022 9:13 AM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Wall wart uses?

 

Any true “wall wart” where the ‘box’ plugs directly into the wall outlet is generally too small in watt and ampere rating to correctly power a DCC booster intended to operate a train. But you  might find one with a 1 to 2 amp rating suitable to operate a booster dedicated to feed DCC to an accessory bus. Be sure to read the nameplate rating and know if the voltage output is regulated or not.

 

DonV

 

 

 

 


Andy - Arlington TX <andy.j1s@...>
 

1 Amp at 12VDC will run a dedicated DCC decoder programming/test track with a SPROG II.

2 Amps at 12VDC will run a DCC++EX setup's motor driver board (the DCC track bus driver) for a small layout running a few N scale locomotives.

-- Andy - Arlington TX


Blair
 

Unintelligible.  Do you mean on the 20VDC range, the meter reads 14.75VDC?  If so, it's unregulated.  Using it for anything that requires 12VDC unequivocally will certainly violate a warranty, and may produce smoke.  Connecting it to anything that wants 15 volts at any reasonable current will be questionable, because the output will 'sag' towards 12V as you draw more current.

Use it for less critical stuff if you want, but remember, as you load it down that voltage will drop, so performance may change.  Me, I'd shelve it or toss it.

Your call.

Blair 

On 24/03/2022 12:20, Richard Neil via groups.io wrote:

20 DCV = 14.75-14.95... use or not?
Thanks_._,_._,_


Don Weigt
 

Richard,

What is the power or especially output current rating? Many wall warts are rather low power, won't even power a programming track. Also, some DC wall warts may only rectify the DC, not filter it with a big capacitor. In that case, it won't power a DCC booster or programmer unless the booster or programmer has a big capacitor on its input, or you add one between the wall wart and the booster or programmer.

If you don't have an oscilloscope or graphing multimeter, it's hard to know whether the wall wart output is filtered or unfiltered DC. One way to tell would be to connect a 100 uF or larger 25 to 50 Volt capacitor to the DC output (plus to plus, minus to minus). If the DC measured across the output and capacitor is about 25% higher than the wall wart output alone, then the wall wart's output is unfiltered.

Simple filtering increases the average output voltage by "filling in" the voltage between rectified peaks. That does NOT increase the power the wall wart can safely deliver. It actually decreases it. But, for example, if the filtered voltage measured divided by the unfiltered voltage is 1.25, then divide the wall wart's current rating by that same 1.25 for an approximate filtered DC current rating. The maximum output power, the current times the voltage, is about the same.

Overloading it too much will at some point result in a drastic reduction in wall wart efficiency, more heat generation, and sagging output voltage. The wall wart probably is safe even if its output is short circuited, but don't rely on that, and don't load it so it's trying to output more wattage (power) than its rating.

Don Weigt

--
Don Weigt
Connecticut


steambigboy
 

On Fri, Mar 25, 2022 at 11:07 AM, Blair wrote:

Unintelligible.  Do you mean on the 20VDC range, the meter reads 14.75VDC?  If so, it's unregulated.

I measured 13.86V on the original power supply which goes with DCS51, I'd expect similar value on the original "wall wart" (2.5A) with DCS50.

  Using it for anything that requires 12VDC unequivocally will certainly violate a warranty, and may produce smoke. 

I'm not aware of any DCC equipment which strictly requires 12V only.

Connecting it to anything that wants 15 volts at any reasonable current will be questionable, because the output will 'sag' towards 12V as you draw more current.

Use it for less critical stuff if you want, but remember, as you load it down that voltage will drop, so performance may change.  Me, I'd shelve it or toss it.

The first concern should be the safety. Does the "wall wart" meet the safety requirement for MRR, specifically the isolation ?

Thanks for reading my post


Blair
 

Has anyone actually read the OP's post, and reply, before chiming in?  Honestly, "Steamiebigboy", what's that got to do with a 400ma 12VDC wall wart?

Wow.  Hilarious.

Blair


steambigboy
 

On Sat, Mar 26, 2022 at 09:45 AM, Blair wrote:
what's that got to do with a 400ma 12VDC wall wart?
In terms of safety, the electricity really does not care about the technical spec of the wall wart. If the wall wart is not designed and tested for use with MRR the technical spec.is irrelevant. The safety question should be number 1.
And the fact that somebody call safety concerns "hilarious" is unfortunate and very sad.....

Thanks for reading my post


Don Weigt
 

Every wall wart I've ever examined closely has all sorts of safety listings printed on it. And, they are used so manufacturers don't need to jump through the hoops to sell products containing the line voltage circuits in the rest of the product, also for compatibility with AC line power all over the world by simply using a different wall wart.

I don't think Blair meant safety was hilarious. But, there's a lot more that goes into reusing a wall wart for a different purpose. Even though I have a dozen or more leftover ones, I haven't yet found one that fit a project's needs. I always have ended up using something else. You may find one that's just what you need, but I haven't yet.

A wall wart may have AC or DC output, if DC it may or may not be filtered, if filtered it may or may not be regulated, finally, its voltage and current ratings may not be compatible with the need.

The only exception to that I've found is all the regulated 5V wall warts that are interchangeable for charging cell phones, tablets, and other electronics. We use one for multiple phones, an emergency radio and my Android tablet.


--
Don Weigt
Connecticut


wyantj01@...
 

Re: “ The wall wart probably is safe even if its output is short circuited, but don't rely on that, …”
I am using a 12v laptop power supply to power my Tortoise switch machines.  I put a 1 amp fuse after the supply because I wasn’t sure what happens to the PS if there is a short.  Not sure if this is a good approach.  Ideally would have some kind of circuit breaker with failure LED.


steambigboy
 

On Sun, Mar 27, 2022 at 02:49 PM, Don Weigt wrote:
Every wall wart I've ever examined closely has all sorts of safety listings printed on it.
Just curious

Thanks for reading my post


steambigboy
 

On Fri, Mar 25, 2022 at 03:25 PM, Don Weigt wrote:
The wall wart probably is safe even if its output is short circuited, but don't rely on that,
The short circuit protection is one of the requirements (mentioned in my previous post) for the power supply for electric toys (MRR). When in doubt, just don't use it.

Thanks for reading my post


Steve Hubbard
 

I am using one of the regulated 3 amp 12VDC wall warts for controlling Handley yards 30 Tortoises and control panel with 2 LED's per turnout and it works fine.  I have left the power on all day and it just gets a little warm.  I plan on using them for other tortoise LCC control systems and Control panels .  I see no reason not to use a regulated wall wart for any Model Railroad application as long as it  provides enough current.