Hello,
I am working on an HO-scale merry-go-round / carousel model for our layout and would like to add lights to it.
Does anybody have any experience with SMD LEDs (Similar to this link found on eBay or this link from a German modeling website )?
I have only ever used grain-of-wheat light bulbs before, but the one's I have in house are slightly too large and do not look right on this model.
I am wondering if I can just solder them together onto a copper wire and then apply power?
Are there any other (easy) alternatives to string miniature lighting which would give a nice effect?
Thanks in advance!
talonboy02 - Welcome to Trains.com!
Darren (BLHS & CRRM Lifetime Member)
Delaware and Hudson Virtual Museum (DHVM), Railroad Adventures (RRAdventures)
My Blog
Welcome to the forums!
I have just started to experiment with the 0603 LEDs so I will be interested in seeing the answers to your questions.
I do have some tricks that I have learned to make soldering easier. I solder the wire perpendicular to the tab on the LED instead of in line with it. It is much easier to keep the wire on the LED tab that way, and the wires come off the LED in a more convenient direction. Some of the 0603 LEDs even have a little cut out in the tab which makes keeping the wire in place a breeze. I also use spring loaded tweezers to hold the LED when I am soldering.
The colour of 'white' LEDs varies considerably from actual 'warm' white to very harsh light blues. I bought some 'blue' white LEDs by mistake but I quickly cured the problem with a yellow Sharpie paint pen.
Dave
P.S. The prices on the German site are a little steep. Try eBay. In one auction I got 50 white LEDs for $1.99 with free shipping!
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Dave, thank you so much for the information. Just a few more questions if possible please.
Do I need any "resistors" or anything like that, or can I just attach the ends to a transformer to power them?
Does any copper wire work?
Also, can you recommend a preferred soldering tool kit?
Thanks again!
Talon,
Just like with a regular LED, a surface-mount LED will need a resistor, too. Also, on the bottom side of the LED is a "T": The top of the "T" denotes the anode (+) and points toward the cathode (-). A resistor can go on either side.
For wire size, you'll probably want to use 30ga hook-up wire. And, given that you are soldering a SMT component - if you can afford it - I'd encourage you to consider an adjustable soldering iron with replaceable tips. (I'm partial to Weller.)
You'll want a fine tip for the SMT LED. You also want to work quickly when soldering so use a drop of flux for a good shiny solder joint.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
You can use #44 magnet wire which is much smaller diameter than #30 DCC wire. I have done that.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.
You can also buy 603 surface mount LED's with wires attached.
There are several sources. They come with two #36 wires attached already. It takes a steady hand and some type of holder to hold the LED's while you solder the wires inplace. For the price (about $2.89 each) might be a lot easier to just buy them with the wires alread on them. I use a 1K resistor for each LED. I work with DCC, so most of the time I use one resistor per each LED.
I usually buy them with the wires attached. BTW, I have filed some of mine to fit into very tight places and to give them a form. The only thing, be careful of the tabs.
Richard
Thank you again for the information everyone.
However, I am still a bit uncertain as to what is exactly soldered where.
Say, for example, I had 100 surface mount LEDs with wires attached (ie: eBay link here). I want to make a strand to recreate this effect:
100 bulbs @ 1.8-2.2 forward Voltage.What do I solder where? For example:
Power source -> copper wire (possibly copper tape) -> LED 1? -> resistor 1? -> LED 2 -> resistor 2 ...and so forth for entire series?Thank you again for any help you can provide!
Sounds like a great project!
The eBay link you posted went to some tower LEDs, not surface mount LEDs you mentioned. Here are some Warm White (yellowish white) 0603 SMD LEDs on eBay for example. Feel free to shop around. I wouldn't go any smaller then the 0603 if your not very experienced with soldering such a small target. However if you feel up for it, 0402 would be even smaller.
Check out this page for a resistor calculator for your LEDs. For this project I would recommend you use the LEDs in series. One resistor for a string of LEDs.
[POWER positive]---[RESISTOR]---[+LED-]---[+LED-]---[+LED-]---[POWER negative]
The LEDs are sensitive to polarity unlike lamps. Make sure you connect them positive to negative.
Using the above example in the calculator we have:
Supply Voltage: 12VVoltage Drop: 3VCurrent: 20mA# of LEDs: 3===========================Resistor required: 180ohm
The required resistor is a MINIMUM! I would always INCREASE the resistor size (330ohm for instance). The LEDs will last longer if you stay farther away from the exact current (20mA). If your resistor is too big, you may get very dim LEDs or they just wont light. If you go too small (below 180)....... they go poof and you have to start over
One more note. I would break the LED strings up into shorter runs. Don't wire 100 LEDs in one string. Break it up into reasonable sections with a resistor for each.
Show some pics when you are done!
talonboy02
Sorry I haven't responded sooner. There is this thing called a job that gets in the way of more important activities swg].
I use a cheap Radio Shack 15 watt pencil style soldering iron. It is not too hot - excess heat will destroy the LEDs.
Any small wire that can be soldered will work. It doesn't have to be copper as long as it accepts solder easily.
Please understand that I am not an electronics expert. My knowledge currently is limited to installing individual LEDs, each with its own resistor. I think your project requires a much more refined approach because it would be near impossible to wire a resistor to each LED on a carousel. As graphitihemi mentions above, there are ways to connect LEDs together so that they 'share' the voltage. I believe that that is the formula used for powering Christmas LED light strings on 120 volts. Hopefully someone will offer some insight.
If the information doen't appear here, you might try custom car forums. Multiple LED setups are popular there.
Thank you everyone - I'm glad I signed up for this website!
Thanks for the link, graphitehemi. If I understand correctly, the tower LEDs have wires, where as the SMDs do not? Is it true the SMDs can be applied directly to copper tape without the need for wires?
Dave - thanks again for sharing your tips. I am learning that it will most likely be a "series" wiring, with a group of about 5-8 lights per strand, which is what I planned on doing.
The first struggle is to figure out how to get the lights to work. The next is going to be, how do I keep them lit and maintain positive and negative connections on a rotating disc! Ouch...why couldn't I just take up oil painting as a hobby instead?
Thanks again.
talonboy02 Ouch...why couldn't I just take up oil painting as a hobby instead?
Ouch...why couldn't I just take up oil painting as a hobby instead?
Have you ever seen a little kid's eyes light up when he sees an oil painting? Neither have I.
I built an HO-scale signal bridge with 10 LEDs. It's a lot of wires in a small space, and I didn't want the wires to show. So, I used magnet wire. It took a while to get used to the technique of working with it, but once I did it worked quite well.
I learned something new from this project. All LEDs are not the same, even out of the same package. When I wired a red LED in parallel with a green one, only one would light, because the resistance was that much different. My solution was to wire them all in series, so the current had no alternate "easy" paths and had to light all the LEDs.
The other valuable tip was something I already knew - test, test, TEST. I keep a 9-volt battery and a pair of clip leads on my work bench. That's enough to test a few LEDs as you wire them, so you don't end up having to tear things apart or break into circuits after they're installed. Yes, you still need a resistor, even with a 9-volt battery as your power source.
Test each LED and mark its polarity before you wire it. If you get one LED in a series string backwards, the whole string will not work. Use a Sharpie to mark the lead, or perhaps a piece of tape on the wire.
It takes an iron man to play with a toy iron horse.
talonboy02If I understand correctly, the tower LEDs have wires, where as the SMDs do not?
A SMD is a "Surface Mount Device". The contacts are wrapped around top bottom and side to allow them to be soldered directly to the top of a circuit board. The tower LED is a "Thru Hole". The leads were intended to be put thru a hole in a circuit board and soldered. The SMD also has much more of a thinner profile.
talonboy02Is it true the SMDs can be applied directly to copper tape without the need for wires?
The only thing that matters is that the connection is reliable. You can just glue the wires to the LED if you want, but will the connection stay? I've never hand my hands on tape so I can't tell you how well it works. There is also a conductive paint available. I've never used that either, but maybe it something you want to take a look at.
talonboy02The first struggle is to figure out how to get the lights to work. The next is going to be, how do I keep them lit and maintain positive and negative connections on a rotating disc!
One 'pre-made' solution is a simple headphone jack. A standard stereo jack will give you 3 contacts that can rotate. Just make sure it is dead center so it doesn't bind up. You could also build your own with however many contacts you want by going with a 'slip ring' method. One example can be seen here all the way at the bottom of the page.