Large Scale Central

LED help

Electronics
#41

David,

I do thank you for all your help and I know I will use this new understanding a lot in my in door as I want all sorts of lights. So don’t think for a second I don’t appreciate it or dismissed it. I filed it away. You helped me come a long way in understanding LED theory. Everyone did. So its not for nothing. Thank you. For the project at hand I will take what I can get. especially with the controller allowing different patterns that wasn’t even in my scope.

But when it comes to wiring buildings and strings of light posts and other stuff the information will be used.

#42

I might buy up a bunch of these things especially in white. If nothing else I will have a bunch of LEDs by just cutting them off. And the fact they are the nano or pico size is perfect. A hundred LEDs for a buck or two.

#43

Yea, I bought a string (or 3) of the larger warm white LEDs last year on sale.

#44

Just picked up a string of 100 warm white and a string of 100 bright white. 75% off. Paid 88 cents each at walmart

Pulled one bulb apart and looks like a 3mm flat top

#45

Yea, I like that part. They are easily adapted to other uses.

#46

I’m getting very hit and miss with my trial run of purchasing strings of Solar LEDS from both the AliExpress and Temu Websites.

I like @David_Maynard1 David’s explanation of approaching the electricity like water flow and pressure. I recently put 15 meters of LED grain of wheat lights in a building and it barely light the building interior.

How do you figure out brightness if lumens are not displayed for the LEDs? If they are too bright can you paint them with something to dim them down?

#47

I cant help you Bill. I still really don’t understand them very well. I can make them do what I want but beyond that I really don’t know much about them.

My source of LEDs and associated gizmos is Lighthouse LED. Maybe they can help. They have a lot of information on their site and good customer service.

One thought is if you are trying to light a bunch of buildings with one string of LEDS what about buying a string of Christmas lights. To " dim" them i would think painting could work

#48

If you want to dim LED just use a higher value resister. For instance on my locomotive I have a 2.2k resister for headlights but for class lights I use a 100k resister. The class lights are much dimmer than the headlights.

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#49

LED’s are pretty much a no brainer, I use 3mm and 5mm LED’s on just about every thing on my RR where I want light, including the engines and passenger cars. I use both Bright White and Soft White LED’s, this depends on where I use them, mainly Bright White for engine headlamps, etc. and Soft White for everything else in most cases. I buy the 12v 20 packs on eBay for around $10/12 dollars and they come with a resistor, plus I add 100 ohm resistors when I want the light a less brightness then what it light up on 12v’s. All my passenger cars, or cars with lighting I run a 9v battery for 3/5 LED’s and as of now I have yet to replace a battery on any of my cars. Using different resistors for light brightness is pretty easy to do, just try different ohm resistors and when the light is to your liking your ready to solder the wires together. You can use all those figures that some have talked about, but what a lot of figuring when not needed, just look at the power voltage, the LED rated power needed, and resistors to control your light brightness. The worst thing that can happen is you overpower your LED and it burns out, I burn my LED’s some times for hours just to make sure my power from my supply will handle the LED and the correct number of resistors. This is just not Rocket Science, more commonsense then anything else.

#50

Thanks.

I was under the impression that standard LEDs were intrinsically not dimmable but that was for house electrics. Is a rheostat and a multimeter helpful in determining the voltage required for targeting the amount desired dimming or is that overthinking the process?

#51

A rheostat is basically an adjustment resister.

My unscientific method is to take a LED and a resister and apply power on a breadboard using the input voltage of the final project. Add more/higher value until I get what I want. Then figure out what the total is, and find a suitable resister.

As I said 2.2k seems to be my “go to” for 90% of stuff.

#52

I use something like this, these are 3mm, I also use 5mm for headlights. Note the resistor is under the light wrapped with shrink tubing. you can also add more resistors to reduce the brightness of the light if so desired. Just get a assorted pack on eBay of resistors, there cheap. Do note the resistors if you add more need to be on the same wire as the resistor is on the bulb wiring resistor. If you don’t get some of these and start your experimenting with LED’s, I don’t think you will catch on very quickly, that’s how I figured it out. 30pcs 3mm 12v Pre Wired Led Diodes Light Ultra Bright Resistor And Wire Indicato | eBay

#53

We buy LED lit sign letters from a factory in China. Their method of determining power supply need is similar. Thy use a high wattage power supply to light the sign and measure the current draw with an in-line ammeter then sell us a supply that exceeds the draw. They do this rather than counting up the number of modules and calculating the current draw based on specs! EDIT to add, the modules already contain the current limiting circuitry for the LEDs.

Personally, in battery powered locos my battery voltage is usually around 14V and the lighting outputs on RailPro are a little less. I start with a 1K resistor and that usually works fine for most. YMMV

#54

I know with DCC decoders the outputs are 5v. I’d wager a guess that Rail pro is also 5v?

#55

RailPro gives you a choice choice since lighting outputs are current sinks, or - voltage. You can feed the lighting with either 5V or battery voltage out which is a volt or two lower than the battery input.

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#56

On RailPro I believe they say to connect the wires to the +5 terminal but the full voltage outputs are there but I do not think they will be worked by the on screen buttons , I think you can hook the headlights this way to work with which direction the loco goes , but have not done that on any of my locomotives

#57

They can. On me 45 Ton diesels, I have a switched battery voltage output that powers two 12V LED modules on my snow plows. RailPro buttons switch the negative lead, so either voltage is switchable. But yes, for LEDs the 5V source is preferred.

#58

It’s pretty awesome, Bill, that your posts often start out under a text line that says “XX years later…”

Cool! Good on ya mate!!

CJ

PS: You’re retired and still married, right? :grin: