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
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.
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.
RR_MelI 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.
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/
JRPHello, I'm looking to install 3 volt LED's in series (street lights, etc.)
(an LED flashlight might use a current regulator to maximize the brightness of the LEDs)
greg - Philadelphia & Reading / Reading
Hello Mel,
RR_MelI 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
RR_MelKevin, 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.
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."
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
RR_Mel I power all my accessories from a 12 volt switching power supply.
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.
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.
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
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.
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
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.
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.
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.
mvlandswCould one of these be used as a DC throttle using the voltage adjuster as the speed control?
mvlandswOr as the power supply for a DCC system.
trainnut1250I'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
if not, wouldn't mistakenly setting the voltage too high blow out all the LEDs?
gregc trainnut1250 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 when you 2.9V, do you have series resistor for each LED? if not, wouldn't mistakenly setting the voltage too high blow out all the LEDs?
trainnut1250 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
when you 2.9V, do you have series resistor for each LED?
Greg,
No I don't use resistors - that is one of the reasons for having the voltage regulators.
I am very careful about setting voltages.....I have thought about using two regulators in series in case of an overvoltage failure....
trainnut1250I am very careful about setting voltages.....I have thought about using two regulators in series in case of an overvoltage failure....
i would think the regulator needs to first be set to a low voltage before connecting any LEDs. after the LEDs are connected the voltage is increased. at first, the voltage may be too low for any of the LEDs to light. then as the voltage is increased after the LED light, they get brighter.
but if the voltage is increased too far they start blowing out
so when do you know when to stop increasing the voltage?
trainnut1250 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
Thanks for the post!!!! So simple, stupid of me to not think of that. But then I only have 70 or so years in electronics.Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
gregc trainnut1250 I am very careful about setting voltages.....I have thought about using two regulators in series in case of an overvoltage failure.... i wasn't suggesting a failure. i was asking how the voltage is adjusted. i would think the regulator needs to first be set to a low voltage before connecting any LEDs. after the LEDs are connected the voltage is increased. at first, the voltage may be too low for any of the LEDs to light. then as the voltage is increased after the LED light, they get brighter. but if the voltage is increased too far they start blowing out so when do you know when to stop increasing the voltage?
trainnut1250 I am very careful about setting voltages.....I have thought about using two regulators in series in case of an overvoltage failure....
i wasn't suggesting a failure. i was asking how the voltage is adjusted.
The converters have a read out for the ouput voltage so I crank them down to well below my target and then adjust back up to desired voltage before hooking up any circuits. The adjustment pots take lots of turns to make the adjustment, so they are easy to set accurately.
RR_Mel trainnut1250 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 Thanks for the post!!!! So simple, stupid of me to not think of that. But then I only have 70 or so years in electronics.Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
Mel,
It wasn't my idea - one of my train buddies is a retired EE and he suggested it after I was complaining about having to fit resistors in structures....
I do agree these converters are kind of addicitve...now several of my train buddies are using them. I have bought a whole bunch and I will just give one to modelers visiting the layout who ask about them and want to try em out. "the first one is free...." LOL!
RR_MelAfter thinking on this I beleive I will go with another converter set to 2.9 volts or so, much easier than trying to cram a resistor in a tight place. I haven't been able to find any micro bulbs in some time so I've been forced to go with LEDs for my vehicles. I've been fighting to squeeze ⅛ watt resistors in my vehicles, with a fixed voltage no resistors needed.
The resistors don't have to go inside the vehicle, they can go anywhere between the power soure and the LED. One problem with driving LEDs without a resistor is different colors (and even the same color often times) have different voltage drops. If you have white headlights, red taillights, and amber marker lights, that's three different voltages. Red and amber voltage drop are pretty close, so you might be able to power them off the same voltage (though you would have no way of individually adjusting the brightness and there's a good chance they wouldn't match), but you would almost certainly have to use a separate voltage for the white.
I normally buy my LEDs in batches of a 100 so coloring should be close.I use glass stain for tail lights and marker lights so all LEDs would be the same voltage. Done it that way for 30 or 40 years with micro bulbs.I have experimented with SMD LEDs using red and amber so those will still need resistors but those are in larger vehicles (18 Wheelers). Easier to use ⅛ watt or chip resistors.
In this Kenworth I used .5mm fiber optics from the amber LED to the roof.
Right now I’m using 5 volts for my LED vehicles and resistors but I think I will see how 2.8 to 3 volts work for headlights using resistors for red and amber or a combo in series.Sure sounds a lot easier if it works.
I had made the connectors from brass rods and tubing for my bulb equipped vehicles fed by 1.35 volts for many years. For my LED vehicles I went with a Arduino style header type connector hopping to prevent voltage problems.Mel My Model Railroad http://melvineperry.blogspot.com/ Bakersfield, California Turned 84 in July, aging is definitely not for wimps.
As others have alluded, you need parrallel wiring over series.For example, a white LED has a forward voltage of ~3.5V
If you wire two of them in series, you will need at least 7V. Three of them 10.5V (3*3.5V)
Anything above 12V, I do not recommend using for an amateur. It gets into "pee your pants" to "Exploding hearts" terratory.
Many people have used White LED lights off christmas tree sets with great success. But you'll have to cut off each one, and add a resistor to each one, and tap into a 12V bus for each one. It's very time consuming. But such is the nature of MRR.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
trainnut1250The adjustment pots take lots of turns to make the adjustment, so they are easy to set accurately.
if they are ~3.4V LEDs, is that what you set them to, 3.40V and no more?
i thought LEDs were spec'd at a max current, not max voltage? and of course that current can be exceeded with care. i've determined resistance values of IR emitters by measuring the current since you can't see their intensity
If you set the voltage to the LED's rated voltage drop you should be fine. They are rated for maximum current, but they also have a current vs voltage curve. For example, the top right graph on page 7 of this LED's data sheet.