I was contemplating a way to light my structures when a lightbulb ([:D]) went off in my head. I could take an old, beat-up strand of christmas lights, cut off the bulb holder with long enough wires still attached, and thread them through the layout to a bus specifically for lights.
My main question is would this work? and would it be wise to wire all of my bulbs in series, or wire them individualy?
Sure, it could work. It depends, though. Some Christmas tree bulbs are designed to run on fairly low voltage; it’s just how they are wired up that lets you plug them into 120V. I would not run them on anything higher than 12v, though. You could probably find a way to run some in series and not use much more than 12V, so I’d experiment with a few bulbs and find what voltage seems to work for you.
I checked into Christmas lights. The standard mini bulb runs on 2.5V, so a string of 50 of them in series will light at 120V. If you wire 5 in series, they will light at 12V, or 4 in series at 10V, or you can have bus that runs at 2-2.5V and wire them all in parallel.
My recommendation would be to wire them in parallel and set your power for 2-2.5 volts. Then, when 1 burns out the others stay lit, otherwise you will play the wonderful game of ‘when 1 burns out, pull all the bulbs out of the structures and check each bulb’ - my experience is that the shorting wire that is supposed to keep the circuit alive when 1 bulb burns out will only work about half the time.
Regards,
John
Divide the number of lights in the string into 120. So a string of 10 lights divided into 120 = 12 volts per bulb. If the string of lights is 14 lights then it’s 8.57 volts for each light in the string. Supply voltage to the string of bulbs, divided by the number of lights in the string of bulbs equal the voltage at each bulb.
120 supply voltage
divided by 100 bulbs
equals 1.2 volts at each bulb.
I would run the bulbs below what the voltage figures at. If your supply is 12 DC I would run two 12volt bulbs in series or 14 1.2 volt bulbs on the same 12 volt supply. By running the lights on a lower voltage they will last longer and not burn as hot either.
BTW the bulbs could care less if it’s AC or DC voltage.
I used Christmas mini bulbs for lighting my structures for years. The power came from an old AT computer power supply. Two bulbs wired in series per structure, each structure getting 5 volts. In nine years I only lost two bulbs and that was with them lit 24/7/365. The only break they got was when Rita knocked the power out for a few weeks. Two of my structures are still lit by Xmas bulbs now. All the others have been refitted with 14 volt bulbs. I’m still using the same computer power supply to light all of them. Twenty-two structures at present. On the old layout there were over fifty lit structures.
I run my 2.5V Christmas-string minibulbs four in series on 6.3vac. This gives a nice yellow light, prototypically accurate for the place and era I’m modeling.
If a brighter, whiter light is appropriate (commercial buildings,) I go with three lamps in series.
I have also adapted them for illuminated route indicators. The series bulbs illuminate critical switchwork in the netherworld under Mount Takami.
Since they are only running on 60-85% of rated voltage, I expect them to last a LONG time.
Chuck (modeling Central Japan in September, 1964)
Yupers, I’ve been doing this since those minature lamps first came out. I was in Junior High … 1969 or so.
Series wiring is generally not wise. One bulb goes they all go out. BUT in Jr. High I would to run them in various combinations of parallel and series depending on the voltage of the power supply I had available. I always try to use at least 0.5 volts lower than the calculation would say. That way they last for a very long time and they aren’t so glarry.
The 100 or 150 bulb strings are 2 or 3 50 bulb series strands wired in parallel. That’s why they have three wires on most Christmas tree lights. They’re 2.5V bulbs. You’re right that it’s better to run them at lower voltage, though, and they don’t care if the power is AC or DC.
Thanks for the input. My next question is; could I use an old train set power pack to light the bulbs, or do I need a more powerfull source? As most of you can probably tell, I’m trying to make due with what I have already.
Absolutely, that is exactly what I was doing in Jr. High when I mentioned I was putting the bulbs into parallel and series combinations to match the voltage of the available supply. As I recall I had an old Tyco with AC16V. I had 9V bulbs so I put sets of two (series) in parallel with other sets of two. You would have to calculate how much power they take with an amp meter, but generally I would add bulbs until I noticed that they dimmed when I added the next. I would remove that “next” one. I would then make certain the power supply did not get hot.
Gray made a very good point. If you use mutable strand lights make sure to count the bulbs in just one strand, not the whole string of lights.
And #722, if you have an old computer sitting around check the link in my signature on how I converted a computer power supply for hobby use.
Your buildings would look really trippy if you used the Christmas tree chase lights. LOL
I did see where someone used amber colored string of chase lights all bunched real close together to represent molten slag runoff in an HO steel mill.