Someone gave me a string of Christmas lights that are not working.
How can I use these to light structures? How do I test to find the problem with the string of bulbs? Each bulb is sitting in it's own socket.
Harold
Harold,
So they're bulbs, not LEDs? Presume they're white, otherwise they have very limited uses...
Mike Lehman
Urbana, IL
Get your multimeter out. Use the DC ma amps scale. A nine volt battery and a 1k resistor. What is the current? I am guessing about 8 MA. If the LED's are the 20 MA max.
With a 12 vdc power pack, about four will probably be the max you can put in series with a 1K resistor.
You are working at the component level. Hope you understand basic electronics.
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.
I Googled the issue. One link from the search. Have fun.
http://cs.trains.com/mrr/f/744/p/183015/2003000.aspx
rich
Before you have a long talk about LED'S. These appear to be incandescent. The Model is RX216-3M 120 vAC 60HZ .6 A Replaces with 2.5 V Lamps.
They fit into sockets on the string. Go back to the original questions. Thanks
If they are the little ones, they should unplug fromt he string, and if you look carefully you will see that there is a bulb and two wires, the wires feed through holes int he little plastic base and are folded over - so you can actually remove the bulb from the base and have just a bulb with a pair of wires coming out of it.
Now for testing - they MIGHT glow dimly on a single D cell battery (1.5V). Another trick is to use a pair of NiCad or NiMH batteries - those cells are 1.2V each, so two in series is 2.4V, still less than the bulb rating. You may need to sacrifice one or two with a slight overvoltage with a meter on ma in series so you cna determine the current draw of each lamp. It's not .6 amps, that's 600ma and more likely the draw for the entire string. Once you know the current of the lamp, you can then calculate the resistor required for a more standard power supply voltage like 12 volts.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
From what I am reading let me ask a question.
If I connect 7 lights in series to the 18vAC side of power supply, would that work?
I'd do 8. 7 is 17.5V, and the "18VAC" output is probably closer to 20 with little to no load on it. Plus bulbs last exponentially longer as you reduce the voltage. Heck, put 10 in series for 18V. SHould still be bright enough.
The only problem with putting a bunch in series, especially if there are some known bad bulbs, is if you put one of the bad ones in your series string, nothing will light up. That's the problem witht he light strings in the first place, they are almost all series wired, so one bad bulb and the whole string is dead, and you have th fun of trying to locate the bad bulb - which is probably why you got this string for free. Too much of a PITA to fix them, just buy a new string for next year.
If you want a bright white light (and short lamp life) seven in series equals 2.57 volts per lamp - slightly over their rated voltage. I personally prefer to run them at 1.6 or 2.1 volts across a 6.3 volt filament transformer. In your case, a ten lamp string equates to 1.8 volts per lamp - and they should last a long time. Also, the resulting light is yellowish - more like what residential lights look like from the outside.
As for finding the dead lamp(s), your multimeter (set on resistance X1) is your friend. A burned out or broken filament won't move the needle (or give a value on the readout.) An intact filament will indicate some resistance, and might even light if it gets a full 1.5V from the multimeter battery.
Chuck (Modeling Central Japan in September, 1964 - with re-purposed icicle lights)
Throw them in the trash. You are going to put a lot of time/effort into something that isn't worth it, especially when those same WORKING lights can be had for pennies on the dollar within a few days/weeks after Christmas. Just last week I bought 50 light strands at stores for less than $1 per box.
Inspired by Addiction
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IF THEY ARE NOT LEDs, DO NOT USE THEM ON THE LAYOUT!
Incandescent Christmas lamps are only about 3 - 5 volts. They have a VERY NASTY feature: a shorting circuit to shunt the filiment incase of failure. In theroy only one light would go out and the rest would remain lit.
That shunting element will put a dead short on your circuit, and could cause damage.
ALSO, in case you have not discovered it yet, those leads are almost IMPOSSIBLE to solder to.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Harold:
If you do use the incandescent bulbs in your structures you would be wise to make them easy to replace. They will burn out eventually even at a lower voltage.
My suggestion is to fight the temptation to try to do something for nothing and use LEDs instead. Warm white 3mm LEDs can be purchased on eBay for pennies each. Here is one example:
http://www.ebay.com/itm/100pcs-3mm-Warm-White-Round-Water-Clear-LED-Leds-/251678078965?pt=LH_DefaultDomain_0&hash=item3a992eb7f5
Resistors can be purchased for pennies too.
http://www.ebay.com/itm/100-x-Resistors-1K-Ohms-OHM-1-4W-5-Carbon-Film-/250870867251?pt=LH_DefaultDomain_0&hash=item3a6911a533
For structure lighting you might want to diffuse the light a bit by sanding the lens lightly or giving it a light coat of white or beige paint. You can also get diffused light LEDs for a bit more money.
In the long run you will regret using bulbs.
Dave
I'm just a dude with a bad back having a lot of fun with model trains, and finally building a layout!
Those christmas lights come in several different voltages, depending on if the string is 20, 35, 50 or 100 lights.
I've never seen a shunt short out the entire circuit. But I have seen the shunt increase the voltage on the remaining lights, and after several have burned out you get a rapid cascading burnout of the remaining bulbs, as the voltage increases with each burned out bulb.
I won't make a long post about them not being LEDs. Others have already noted you're better off just pitching that mess and buying something working. Even then, it's just so much easier for several reasons to use LEDs than these sorts of bulbs.
Thanks Guys
Just a note . Today is gabage day.
hobo9941I've never seen a shunt short out the entire circuit. But I have seen the shunt increase the voltage on the remaining lights, and after several have burned out you get a rapid cascading burnout of the remaining bulbs, as the voltage increases with each burned out bulb.
The whole set, no. But if you salvage the lamps to use individually, then you certainly are in for a rough ride with those things.
In the normal course of those lamps, a failed filiment would put the full 110 volts across the gap which would be enough to fuse the shunt into place. DC voltages would also weld the shunt in place in the event of a filiment failure, since DC arcs more readily than AC.
You best bet is to salvage the wires without the sockets on them, and toss the rest. They are not worth the effort. With LED sets there are three wires running the length of the set, only one has sockets on it. From a 35 foot set you could salvage 70 feet of wire. Incandescent sets only have two wires, one with sockets and one without.
PennCentral99 Throw them in the trash. You are going to put a lot of time/effort into something that isn't worth it, especially when those same WORKING lights can be had for pennies on the dollar within a few days/weeks after Christmas. Just last week I bought 50 light strands at stores for less than $1 per box.
+1000!!!
But even more so - do you even want to use a new set of cheap lights which are going to do the same thing at some point down the road? NO! Remember how hard it is to found out which bulb is to blame for the whole set to stop working? Now if you use those, you'll have to pull each and every building! Either that or pull your hair out!
I know it's tempting to use inexpensive christmas lights for building - I'm a cheap-o person too but when I heard about LED christmas lights this year for the first time I was glad that there was now hopefully a better alternative to the crappy mini-lights that have plauged America for most of my adult life! They are a horrble design and one of the worst inventions to hit our fair country.
My sister got me and my wife a Christmas tree with build in cheap-o mini lights last year as a house warming present and a is usual, part of the string won't light and I gave up trying to get it working and tossed on a couple strings of working lights.
I truly hope the new LED lights work much better so we can all throw away our crappy mini Christmas lights for good!
Rio Grande. The Action Road - Focus 1977-1983
When LION uses LED strings, he reacues the individual LEDs.
Do not salvage the socket and wires, there may be a resistor inside of that device. Different manufacturers do things differently. Some will have resistors in several of the sockets, and others will have a larger resistor in a plastic enclosure.
I INSISTED that no more old-style lights go up this year, everything was LEDs. I had some big ones that emulate the old large bulb, like the C7 and C9 size, with multicolor LEDs that were bluetooth controlled from my phone. And other plain LED light strings and net lights for the bushes. I should just throw out the incandescent ones, so they don't get used again. I've repalced most of my house lights with LEDs, not cheap but I should never have to replace them, and they use even less power than CFLs - critical when some household members have a tendency to leave lights on all night long. My new layout will be all LED lit.
-Randy