Author Topic: Christmas mini lights (filament/incandescent, not LED) - question about voltages  (Read 4471 times)

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Offline SolderSuckerTopic starter

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I have some Christmas mini lights (filament), the type on a wire loop that plug directly into the mains with no transformer or control box with assorted settings. They're either on or they're off. The bulbs are the push-in type that look like this:

https://www.thechristmasshop.co.uk/p/coloured-bulbs-for-140-konstsmide-lights

Because I'm in the UK the mains voltage is 240 volts - as the string of lights plugs straight into the mains that of course doesn't mean the bulbs are each capable of handling 240 volts. I always thought that they were usually rated at around 9 volts (but now see from looking online that some even start at 1.5 volts). Because they are wired in series on a string that means that the voltage is 'evened out' between the bulbs (there's 100 on a string). Therefore in series that's 100 mini lights and a mains voltage of 240, meaning each bulb is rated at 2.4 volts? Is that correct?

I also note that if I bend out the wires on the base I can test them individually with a small 9 volt PP3 battery and the light seems as bright as it is when they are on the string powered from the mains. However if they really are only 2.4 volts each then I need to be careful to only very quickly check any suspect ones at 9 volts .......

In addition to the above does anyone know if there's a list anywhere of the different sizes and voltages of filament mini lights? I've tried Googling but to no avail. I know that some have a slightly wider base for example and they don't plug into some light strings with push-in holders that are designed for a slightly narrower base, other have a slightly different shaped base. It would be useful to be able to look at a table when ordering spare bulbs to ensure that the right size and voltage is purchased. Unfortunately these mini lights of different sizes don't seem to have any markings, I guess there's no industry standards then?
« Last Edit: October 28, 2023, 06:28:17 pm by SolderSucker »
 

Offline mendip_discovery

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Why bother with them. They regularly use different/proprietary bulbs so it's always been a pain to use them. They also had a nasty habbit of catching trees on fire etc.

This is one of those times were it's really nice to have LED.
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Offline SolderSuckerTopic starter

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I really hate LED Christmas bulbs - the colours are usually slightly off/unnatural and the light is overly bright and harsh. Blue light in particular is the worst.

Filament bulbs are a lot better (for me at least) as they give off a far nicer, softer glow.

But if you prefer LED bulbs then that's fine, we all have different preferences.
« Last Edit: October 28, 2023, 06:41:00 pm by SolderSucker »
 
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Offline mendip_discovery

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I am quite lucky to find a set that is a lot like the old lights so not that far off. I will admit some of the lights I see now have horrible glare so I find them distracting. Don't get me started on all those people with the blue lights on outdoor trees/hedges set to flash blue light drives me potty.
Motorcyclist, Nerd, and I work in a Calibration Lab :-)
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So everyone is clear, Calibration = Taking Measurement against a known source, Verification = Checking Calibration against Specification, Adjustment = Adjusting the unit to be within specifications.
 

Offline Gyro

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There are a few different types base moldings... and voltages, 100 is a long string, most are / were 24, 36 etc. The voltages aren't necessarily matched to the bases - I remember for years the family had strings with a mixture of dim and bright bulbs.  The reason that you have similar brightness on battery is that the PP3 battery probably has limited current availability. Either that or there is more than one string in parallel - but in that case, there would be more wires than a simple loop.

Flilament lamp strings are (were) cheap disposable items, supplied with a few spare bulbs (including a couple of spare white topped fuse bulbs). By the time one bulb blows, all the others have reached the far end of the bathtub curve.

I agree that traditional filament lamp strings look better (well, more traditional) but theyt are really at EOL from the safety perspective, cheap single insulated wire and no strain relief in the holders, a definite young kid and pet risk, they wouldn't pass a safety inspection these days. There are at least plenty of LED sets that default to power up in steady illumination rather than brain-frying psychedelic mode.
Best Regards, Chris
 
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Offline Ian.M

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'Back in the day', I had to maintain several antique strings of Osram Christmas lights on a yearly basis, and getting spares was always a problem.   Key parameters to match are no. of lights in the string and bulb wattage.  As you are using push-in bulbs, if you are having difficulty finding ones that fit, keep the bases off any blown bulbs as they can be transplanted to new bulbs.

One absolutely key detail you must be certain of is whether or not the set uses self-shorting bulbs. Self-shorting bulbs have a wrap of thin magnet wire internally round the two leads supporting the filament (which can be seen if you look closely).  If the filament goes open, the mains voltage breaks down the magnet wire insulation, spot-welding it to the leads and shorting out the bulb so the rest of the lights stay on, albeit at a fractionally higher voltage.  This decreases the life of the other bulbs so its critical to stay on top of checking for and replacing dead bulbs for the duration of your display.  Self-shorting bulb sets *MUST* have a fuse bulb (a special bulb without the shorting wire and with enough lead separation that it wont arc over when it fails, identified by a white paint dipped tip) fitted in one socket (usually the one next to the supply lead), or an appropriately rated mains fuse (and no, even a 3A BS1362 fuse in the plug isn't sufficient protection), to prevent them becoming a fire risk.
« Last Edit: October 28, 2023, 07:00:16 pm by Ian.M »
 
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Offline mendip_discovery

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Would be nice to go full Matt Parker on the LED tree lighting.
Motorcyclist, Nerd, and I work in a Calibration Lab :-)
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So everyone is clear, Calibration = Taking Measurement against a known source, Verification = Checking Calibration against Specification, Adjustment = Adjusting the unit to be within specifications.
 

Offline Gyro

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If the filament goes open, the mains voltage breaks down the magnet wire insulation, spot-welding it to the leads and shorting out the bulb so the rest of the lights stay on, albeit at a fractionally higher voltage.

I believe they use Aluminium wire, relying on oxide breakdown to make the short. Of course there's no Oxygen in the bulb to prevent it from alow it to re-forming. Yes, the fuse bulb is vital, a clear bulb with a white painted top (in the UK anyway).
« Last Edit: October 28, 2023, 07:08:12 pm by Gyro »
Best Regards, Chris
 

Offline Ian.M

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Thanks for the correction - that makes more sense than magnet wire.
 

Offline wraper

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I really hate LED Christmas bulbs - the colours are usually slightly off/unnatural and the light is overly bright and harsh. Blue light in particular is the worst.

Filament bulbs are a lot better (for me at least) as they give off a far nicer, softer glow.

But if you prefer LED bulbs then that's fine, we all have different preferences.
Just buy decent looking LED lights. For similar cheap price you can get them both with nice warm colors or totally awful. Those incandescent lights are an absolute rubbish. Not only they are not electrically safe, they are very unreliable. Going for a week with no failures is very unlikely.
 
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Offline IanB

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Just buy decent looking LED lights. For similar cheap price you can get them both with nice warm colors or totally awful. Those incandescent lights are an absolute rubbish. Not only they are not electrically safe, they are very unreliable. Going for a week with no failures is very unlikely.

I've done for fairy lights the same as I have done for other incandescent lamps. Run them on a dimmer at reduced brightness. Then they run for years without failure. Most of the time full brightness is too much for me, subdued lighting is much more pleasant. So it's a win-win situation.
 
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Offline SolderSuckerTopic starter

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I really hate LED Christmas bulbs - the colours are usually slightly off/unnatural and the light is overly bright and harsh. Blue light in particular is the worst.

Filament bulbs are a lot better (for me at least) as they give off a far nicer, softer glow.

But if you prefer LED bulbs then that's fine, we all have different preferences.
Just buy decent looking LED lights. For similar cheap price you can get them both with nice warm colors or totally awful. Those incandescent lights are an absolute rubbish. Not only they are not electrically safe, they are very unreliable. Going for a week with no failures is very unlikely.

I've used filament lights for some time but after a recent break (while I tried LED lights) I went back to them. Only ever had a problem with bulbs failing and then not that often. Bulbs these days also have a built-in shunt, so when one bulb dies it doesn't take the whole string with it and the dead bulb is easy it identify. They are definitely not "absolute rubbish".

I've tried all kinds of LED bulbs, both cheap and expensive, and none have appealed - their harsh and incorrect colours are not to my taste.
 

Offline SolderSuckerTopic starter

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Just buy decent looking LED lights. For similar cheap price you can get them both with nice warm colors or totally awful. Those incandescent lights are an absolute rubbish. Not only they are not electrically safe, they are very unreliable. Going for a week with no failures is very unlikely.

I've done for fairy lights the same as I have done for other incandescent lamps. Run them on a dimmer at reduced brightness. Then they run for years without failure. Most of the time full brightness is too much for me, subdued lighting is much more pleasant. So it's a win-win situation.

I've never tried a dimmer with the filamant lights - is there any particular type that you would recommend?
 

Offline IanB

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I've never tried a dimmer with the filamant lights - is there any particular type that you would recommend?

Any regular lamp dimmer will do it. In the USA there are "table lamp dimmers", which have a socket you can plug a table lamp (or fairy lights) into. I have not looked to see if you can buy such a thing in the UK, but I would guess they are available somewhere.
« Last Edit: October 28, 2023, 11:53:32 pm by IanB »
 
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Offline Zero999

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If the filament goes open, the mains voltage breaks down the magnet wire insulation, spot-welding it to the leads and shorting out the bulb so the rest of the lights stay on, albeit at a fractionally higher voltage.

I believe they use Aluminium wire, relying on oxide breakdown to make the short. Of course there's no Oxygen in the bulb to prevent it from alow it to re-forming. Yes, the fuse bulb is vital, a clear bulb with a white painted top (in the UK anyway).
I thought they used a low pressure gas, with a low breakdown voltage, which would drop to a normal filament lamp, once the arc had struck.
 

Offline TimFox

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For some reason, the normal LED strings sold here for Christmas lighting are much brighter than my wife and I like.
 

Offline Gyro

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A totally off the wall suggestion, which might look really ugly!... https://www.ebay.co.uk/itm/111023835999
Best Regards, Chris
 

Offline AndyBeez

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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.
« Last Edit: October 28, 2023, 11:41:14 pm by AndyBeez »
 

Offline Brumby

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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.
 
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Offline IanB

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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).

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.
 

Offline tom66

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If you find LED Christmas lights too strong for your taste, a bit of permanent marker (in the colour you want) can turn white lights of your choice into more pleasant alternative colours.   And it usually lasts the season because the LEDs don't get too warm.  It can also tweak the colour of existing coloured lamps though you've got less to work with in brightness terms.
 
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Offline themadhippy

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Instead of a dimmer chuck a suitable capacitor  in series with lamps.
One of my earliest shocks was thanks to christmas tree lights,its only 12 volts so perfectly safe to play with,nope.
 

Offline IanB

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Instead of a dimmer chuck a suitable capacitor  in series with lamps.

This doesn't make sense. A dimmer is a robust, consumer safety-tested, insulated device. A capacitor is a bare metal component with exposed leads. The one is not like the other.
 
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Offline themadhippy

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Hopefully people around here are aware  not to leave a cap thats connected to the mains flapping around in the breeze,just as there aware not to use a  dimmer that's not in a suitable enclosure
 

Offline NiHaoMike

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Or use a diode, trivial to seal up in heat shrink.
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Cryptocurrency lesson 0: Altcoins and Bitcoin are not the same thing.
 


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