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LED power source

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  • Member since
    July 2009
  • From: lavale, md
  • 4,678 posts
Posted by gregc on Sunday, April 3, 2022 5:03 AM

mvlandsw
Could one of these be used as a DC throttle using the voltage adjuster as the speed control?

you could replace the multi-turn potentiometer with a single turn one as on many DC throttles, but don't many DC throttles introduce pulses for better low-speed performance to overcome sticktion.    and DC throttles don't require such precise voltage control

mvlandsw
Or as the power supply for a DCC system.

these are regulators that require a AC adapter (an unregulated power supply) themselves.   most of todays electronic include such regulators themselves

greg - Philadelphia & Reading / Reading

  • Member since
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  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Saturday, April 2, 2022 10:03 PM

Everything in my posts above are for fixed voltage and or current and that is the intent of switching power supplies.  Very efficient constant voltage.


Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
Turned 84 in July, aging is definitely not for wimps.

  • Member since
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Posted by mvlandsw on Saturday, April 2, 2022 9:31 PM

Could one of these be used as a DC throttle using the voltage adjuster as the speed control? Or as the power supply for a DCC system.

  • Member since
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  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Saturday, April 2, 2022 2:12 AM

I should have been more specific on the 12 volt switching power supplies I’m using.

https://www.ebay.com/itm/174834024019?hash=item28b4eb7e53:g:gNIAAOSwSqZgxLs-

I have two 12 volt 15 amp and one 12 volt 30 amp power supplies.  I bought one 15 amp for my layout and the second for a bench/test power supply.  When my layout current was approaching 15 amps I paralleled the two 15 amp supplies as a precaution.  Over time as the current increased and needing my bench power supply back I ordered a 30 amp for my layout.

The lighting on my layout is primarily incandescent and the current is relatively high.  I have about 350 12 volt Grain of Wheat bulbs also operating at 70% for longer life and better realism.  I have the GOWs split on two 8 amp Buck Converters set to 8.5 volts.  About half of the GOWs are driven off Arduino Random Lighting Controllers.

The 30 amp power supply and the 7 Buck Converters do very well and the best thing is they run very cool.  The 30 amp power supply has a fan that comes on as the current increases, I can’t feel any heat and the fan is very quite running.

Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
Turned 84 in July, aging is definitely not for wimps.

  • Member since
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Posted by trainnut1250 on Saturday, April 2, 2022 1:09 AM

I'm a convert to the buck voltage regulators after Mel posted about them a few years ago. I have about ten in use on the layout currently set at various voltages - mainly 1.3V for mini bulbs and 2.9 volts for LEDs - I'm a big fan

Guy

see stuff at: the Willoughby Line Site

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  • From: Christiana, TN
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Posted by CSX Robert on Friday, April 1, 2022 10:30 PM

Ablebakercharlie

I took a look at a 12v switching supply on-line and the one I saw had a connection for the ground.  Assuming that is how all these types of power supplies are configured what do you connect the ground connection to?  

Sorry I don't have a picture. The connections on the device were: 3 outputs V+, 3 outputs V-, 1 for the ground, and finally the pos and neg inputs for the AC.

Thanks!

charles

 

No, they are not all like that, there are several differnt kinds.  In fact, nowadays most "wall warts," are switching power supplies, as are the typical cell phone block charger.

When they have V+, V- and GND, GND is the common refernce for the voltage outputs.  For example, say you have +12, GND and -12.  If you go between +12 and GND, you'll get 12 volts with the +12 positive and the GND negative.  If you go between -12 and GND, you'll get 12 volts with the GND positive and the -12 negative.  If you go between +12 and -12, you'll get 24 voltas with the +12 positive and the -12 negative.

You can power devices off whichever two terminals you want as long as you don't exceed any current limits.

JRP
  • Member since
    November 2006
  • From: Upland, CA
  • 301 posts
Posted by JRP on Friday, April 1, 2022 9:39 PM

Wow, I had no idea I would open so many discussions and ideas.  I think mine is pretty simple.  I have two 4 foot modular boards (for Ops) that connect using pins and runs on DCC.  I will have a total of 41 LED's, all 3 volt and wish to operate each board lighting with an on/off switch.  Whether I go parallel or in series depends on what will work best for my situation. They each have pro's and con's. I want to avoid running alot of wire, and would like to "plug and play".  You have all given me great ideas and I appreciate it.  72 years old and still plays with trains in Upland.  Thanks 

JRP 

  • Member since
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  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Friday, April 1, 2022 7:01 PM

BATMAN

I ordered a bunch of these from China for $2.00ea. They were here in eleven days. I use an old adapter for a power source.

They have about a 20% failure rate but at $2.00 each, I can handle that.

 

 

The failure rate surprises me, I have 16 Buck Converters without a failure.  I have 4 of the ones pictured on your post, all work great.  My standard is the 8 amp continuous duty.

The regulation on the Buck Converters is better than great!!

I continuously monitor the 1.4 volt regulator, actually 1.35 volts, and it never changes.

I have a switchable panel meter for my Buck Converters.






Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
Turned 84 in July, aging is definitely not for wimps.

  • Member since
    January 2009
  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Friday, April 1, 2022 6:06 PM

Ablebakercharlie

Hello Mel,

 

 
RR_Mel
I power all my accessories from a 12 volt switching power supply.

 

I took a look at a 12v switching supply on-line and the one I saw had a connection for the ground.  Assuming that is how all these types of power supplies are configured what do you connect the ground connection to?  

Sorry I don't have a picture. The connections on the device were: 3 outputs V+, 3 outputs V-, 1 for the ground, and finally the pos and neg inputs for the AC.

Thanks!

charles

 

The switching power supply negative is isolated from Earth ground and I use the negative as common on my layout.

To prevent accidental problems I use two 12 volt sources on my layout so that I can isolate the 1.4 volt common from the higher voltages when I’m working on the wiring.  When I’m not working on wiring or the electronics on my layout I use a common 12 volt source.

I’m a klutz and if there is a way to screw something up I will find it and boom.  I have 300 1½ volt micro bulbs and I’m very protective of them.

I also use 18 volts AC for my turnout solenoids and it is floating on my layout.

Even with all the different voltages I use on my layouts since 1951 I’ve never crossed them.  I’m very particular on the wiring, I follow my specific color code with all the wires on my layout.  I label all the terminal blocks (bussbars) for voltage.



Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
Turned 84 in July, aging is definitely not for wimps.

 
  • Member since
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  • From: 4610 Metre's North of the Fortyninth on the left coast of Canada
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Posted by BATMAN on Friday, April 1, 2022 4:22 PM

I ordered a bunch of these from China for $2.00ea. They were here in eleven days. I use an old adapter for a power source.

They have about a 20% failure rate but at $2.00 each, I can handle that.

 

I use this LED Wizard to help my tiny brain design the thing.

http://www.hebeiltd.com.cn/calculator/v5/led.php 

 

 

Brent

"All of the world's problems are the result of the difference between how we think and how the world works."

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Posted by SeeYou190 on Friday, April 1, 2022 4:05 PM

RR_Mel
Kevin, glad to see you back!!!!

It is great to be back. I have been able to post again for about three days.

Thank you for the answer and the suggestion. I have ordered two of the Buck Transformers to try out.

-Kevin

Living the dream.

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  • From: Vermont
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Posted by Ablebakercharlie on Friday, April 1, 2022 3:13 PM

Hello Mel,

RR_Mel
I power all my accessories from a 12 volt switching power supply.

I took a look at a 12v switching supply on-line and the one I saw had a connection for the ground.  Assuming that is how all these types of power supplies are configured what do you connect the ground connection to?  

Sorry I don't have a picture. The connections on the device were: 3 outputs V+, 3 outputs V-, 1 for the ground, and finally the pos and neg inputs for the AC.

Thanks!

charles

  • Member since
    July 2009
  • From: lavale, md
  • 4,678 posts
Posted by gregc on Friday, April 1, 2022 5:42 AM

JRP
Hello, I'm looking to install 3 volt LED's in series (street lights, etc.)

an unused wall adapter can be used.   i doubt you could find one with the exact voltages for your LEDs and each would require a series resistor depending on the voltage (a 5-8V supply would be good)

(an LED flashlight might use a current regulator to maximize the brightness of the LEDs)

greg - Philadelphia & Reading / Reading

  • Member since
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  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Friday, April 1, 2022 2:38 AM

Kevin, glad to see you back!!!!

I have used 12 volts for my primary accessory power since I started out in HO (1951).  For many many years I used regulators to reduce the voltage.  About 5 years ago I bought my first DC to DC Buck Converter to replace my 1.4 volt regulator.  The regulators always work OK but are very inefficient and put out a ton of heat.  The Buck Converter is a switching power supply and super efficient, upper 90%, very little heat.

When I first picked them up the price was really good but like everything else they have skyrocketed.  I was buying a 8 amp continuous duty converter off eBay for under $3, now $10 is the going price.

You can adjust the output voltage from 1.2 volts to about 11 volts when powered by 12 volts.  Their regulation is better than fantastic from no load to max load.

I have 98 HO vehicles on my layout each has two 1½ volt micro bulbs for headlights and a third for taillights.  The load on that converter is 5 amps at 1.4 volts and no heat for just under 300 bulbs.

I started out with a 12 volt 15 amp switching power supply around 10 years ago and two years ago I ran out of current, I replaced it with a 30 amp and currently with everything on it is at 17 amps.  I have lots of goodies on my layout, 1.4 volts, 4.5 volts, 5 volts, 8.5 volts and 12 volts.

I  almost forgot to answer your question, two wires in from supply voltage and two wires out at the adjusted voltage.  They also have adjustable current out.

Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 

  • Member since
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  • From: Southern Florida Gulf Coast
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Posted by SeeYou190 on Friday, April 1, 2022 1:09 AM

RR_Mel
I use adjustable DC to DC Buck Converters.

I had never heard this term.

I just looked it up on Amazon, and I found a neat product I never knew about.

How are these used? It looks simple enough.

-Kevin

 

Living the dream.

  • Member since
    January 2009
  • From: Bakersfield, CA 93308
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Posted by RR_Mel on Thursday, March 31, 2022 10:18 PM

I power all my accessories from a 12 volt switching power supply.  To get the individual voltages I use adjustable DC to DC Buck Converters.

The Converters are available from 1 amp to 12 amp capacity.  I have five Converters, 1.4 volts for 1.5 volt micro bulbs, 4.5 volts for Micro Engineering Signs, 5 volts for LEDs and Arduinos, 8.5 volts for 12 volt bulb structure and street lighting and 12 volts for 12 volt accessories.

Very efficient power distribution.  I operate all my incandescent bulbs at 70% for max bulb life and realism.

 
Mel


 
My Model Railroad   
http://melvineperry.blogspot.com/
 
Bakersfield, California
 
Turned 84 in July, aging is definitely not for wimps.

  • Member since
    February 2007
  • From: Christiana, TN
  • 2,134 posts
Posted by CSX Robert on Thursday, March 31, 2022 8:23 PM

I think you mean in parallel.  If you wire them in series you have to add their voltages and have a power supply greater than the sum.  With a 12 volt supply and 3 volt LEDs, you would be limited to 3 or 4 LEDs (a 12 volt supply would light 4, but you're really supposed to have a supply greater than the sum and use a current limiting resistor, so that would be 3).

You can also wire them in series-parallel to save energy.  For example, you could have groups of three wired in series and then have each of those groups wired in parallel with each other.  Having groups of three instead of having them all parallel would use 1/3 of the energy (and only require 1/3 of amperage on the power supply).

How many LEDs do you want to light?  That's going to have a big effect on what kind of power supply you need.  Many of us have various "wall warts" lying around that are no longer used for their intended purposes that we recylce to use on the layout.

 

JRP
  • Member since
    November 2006
  • From: Upland, CA
  • 301 posts
LED power source
Posted by JRP on Thursday, March 31, 2022 7:53 PM

Hello, I'm looking to install 3 volt LED's in series (street lights, etc.) and want to know what's the most economically and simplest power source to use.  I want to be able to operate these lights separately from my DCC track power.  I 'm familiar with Woodland Scenics "Just Plug" systems, but it tends to get pricey.  Thanks

JRP

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