General > General Technical Chat
Christmas mini lights (filament/incandescent, not LED) - question about voltages
TimFox:
For some reason, the normal LED strings sold here for Christmas lighting are much brighter than my wife and I like.
Gyro:
A totally off the wall suggestion, which might look really ugly!... https://www.ebay.co.uk/itm/111023835999
AndyBeez:
We have been driving our retro incandescent Xmas lights with a dimmer for many seasons. Running at 80% has little impact on visual brightness but, reduces heating and extends the lifespan of the strings. Also, a dimmer provides a soft start, treating the ageing filaments with care. I have zero idea if spare bulbs even exist. One string is so retro, the bulbs are LES fitting.
Image. I cannot recommend this dimmer as I do not own one but, such plugin devices exist for UK sockets. This one is quoted at 300W. Be sure to downrate the fuse in your festive light string's plug to 3 Amps. I should add that a dimmer is not ever compatible with mini LED transformers - they are buck converters and will likely buzz very loudly if dimmed.
Brumby:
My only foray into Christmas tree light fun and games originated in the days of filament only globes wired in series for plugging directly into the mains supply.
The first set I remember had a string of globes rated for 17V. They had a screw base and, from memory, were about 5cm or so long (it's been a while). These were in the days of, if one globe failed, the whole string went dark. Chasing down the faulty globe was THE Christmas ritual nobody liked (I didn't buy my first multimeter until some years later).
In the early days, flashing lights consisted of one "special" globe that, when fitted, would make the whole string flash. Yes ... bang - bang. All on, all off. It was quite dramatic - and in those days, a cool feature.
We then got an "aluminium" Christmas tree - tripod base, wooden pole trunk with angled holes and steel rod branches with fringe cut "aluminium" (more like a metallised plastic sheet, I reckon) spiral wrapped around them for the leaves. It was very pretty, albeit completely inorganic, but not the place to run a string of lights that came with a 240V risk, so the old lights were draped over a timber slat divider, well away from danger.
Anyway, I had an idea.
I purchased a set of 20 lights - again full mains operation - and confirmed a series connection of all the globes, which indicated they operated at 12V.
First step was to cut off the mains plug and toss it. I then ran a length of 2 conductor cable down the string and joined each conductor alternately to the light string, resulting in 20 globes wired in parallel. I now had a 12V set. Connect this up to a 12V transformer and the electrocution risk was gone. Care was taken to prevent any wayward "leaves" being a problem and over the years, there never was one - even though I did a spiral wrap with some thin tinsel to keep the wiring together and camouflaged.
This configuration had another benefit.
The bang-bang flashing behaviour could now be tamed. By replacing a normal globe with a flashing globe, only that one globe would flash. With my new setup, I had 3 flashing globes, so I was able to set up the string so that most of the globes were on full time and only 3 globes were flashing - and they were flashing at different rates, so that after a minute of operation, they were so out of step, the result was random twinkling. This was so much more appealing.
A year or two later, I did a similar thing with a string of 40, wiring them as 20 lots of two 6V globes in series, again working from 12V.
IanB:
--- Quote from: Brumby on October 28, 2023, 11:54:10 pm ---The first set I remember had a string of globes rated for 17V. They had a screw base and, from memory, were about 5cm or so long (it's been a while). These were in the days of, if one globe failed, the whole string went dark. Chasing down the faulty globe was THE Christmas ritual nobody liked (I didn't buy my first multimeter until some years later).
--- End quote ---
I seem to recall from my childhood that some of the strings had special sockets that shorted out if you removed the bulb. So finding a faulty bulb just involved removing each bulb in turn until the string came back on. Also, if you had a faulty bulb on Christmas Day with no spares available, you could just remove the faulty bulb until you could obtain a replacement.
There were also, of course, the bulbs that failed short internally as noted above, so all you had to do was to look for the dead bulb.
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