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Children's lights

Discussion in 'Electronics & Electrics' started by Kommandant33, May 20, 2013.

  1. Kommandant33

    Kommandant33 Member

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    Hey all,

    I have a string of light up in my daughters room, they are farm animal themed and very cute - and they give a really nice warm light, but I noticed one of the lights had blown yesterday, and the bulb had gone black (see attached photos). Even though the bulb was blown, the lights still worked (I guess it was still a circuit?) and I went to turn it on today and it didn't turn on - on closer inspection, most of the lights were now black.

    So
    1. Is it dangerous to have kept it on with one blown bulb AND should it not have discolored like it did?
    B. Can anyone tell me what bulb that is, if it is some sort of standard, and once I use all 4 spares it came with, will I be able to replace any more?

    [​IMG]
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    Any advice would be great - thanks in advance,

    Komm
     
  2. ChoppedLiver

    ChoppedLiver Member

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    so their saying the bulbs are in series with each other.
    if one failed (went short circuit) the rest would get a slightly higher voltage.
    if one failed (went open circuit) the rest would go out.

    as to what the bulbs are, you could see what the transformer is supposed to give, and work out bulb voltage and power draw from that..
     
  3. driver

    driver Member

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    I've found when Christmas Lights fail in a close circuit, the increased voltage on the remaining lights will almost always make the rest blow exponentially quicker.
     
  4. Supplanter

    Supplanter Member

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    They almost look like T5 or T10 automotive globes, at least the socket end does.
     
  5. sbadman

    sbadman Member

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    This. Christmas light bulbs have a 'bypass' element that goes into effect when the filament blows, essentially the bulb is shorted out. On a long Christmas light string with many bulbs the voltage increase is minor, on a short string of lights with few bulbs the volt increase will be more significant.
     
  6. kjparker

    kjparker Member

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    Had you considered replacing the globes with leds?

    Chop the mains plug off, solder on an appropriate line socket, use an appropriate wall wart, and your away!

    It looks like you could simply straighten the legs on the existing globes, and slide them out of the holders. Once done slide the led Legs through the holes in the holder and trim appropriately.

    Would be safer in a childs room IMHO anyway!
     
  7. Bravs

    Bravs Member

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    I agree with kjparker, should get a plug pack (12V or higher). I'm sure you have heaps lying around and just replace those globes with leds. You could also build up a small circuit with an 4060 and some resistors/capacitors, and have the leds randomly go on.
     
  8. RobRoySyd

    RobRoySyd Member

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    How is simply replacing the lamps with LEDs going to work?

    The exiting lamps are wired in series, probably about 20 of them.
    20 LEDs is series will need around 40 V DC.
     
  9. kjparker

    kjparker Member

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    Didn't do the maths, your 100% correct, however 48v plugpacks are readily available on the bay for very little.... You wont need many amps for this I would expect.....
     
  10. RobRoySyd

    RobRoySyd Member

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    That'd get the LEDs to light up, one problem solved.

    The next problem is the nature of LEDs themselves, they have a very narrow beam. Given that they have to light up those translucent figures I see another problem for the OP to wrangle.

    Probably the best solution would be the "acorn" style LED lamps sold as replacements for automotive tail lights etc. Buy matching sockets then rewire them in parallel and run the whole thing off a 12V DC plug pack.

    Certainly getting away from the existing arrangement that has the 240V active running around in thin single insulated wire in a kids bedroom is a commendable goal if for nothing else than safety.
     
  11. 2xCPU

    2xCPU Member

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    Never seen one - got a link?
    Could you crunch the numbers and convince us you've actually thought about this?

    2.
     
  12. Pat

    Pat Member

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    Also known as throw away that nearly brand new set of lights you have and ghetto up a LED string of lights and stick the felt farms animals around them.

    I also have these lights and am more inclined to put in a fire alarm in the kids room then wire up a replacement.
    PS. also don't let your kids play with scissors on their own in their rooms and do try and teach them some electrical safety.
     
  13. kjparker

    kjparker Member

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    Here's a 48v 2a supply http://www.ebay.com.au/itm/New-YU-4...ronics_Batteries_Chargers&hash=item4ac07dcee3

    Wether that's enough current or not, depends on the leds used.

    I'm not going to get into a pissing competition with you, and I don't have to convince you. You can always feel free to disregard my suggestion.
     
  14. OP
    OP
    Kommandant33

    Kommandant33 Member

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    Hey all - thanks for all the advice, but as per advice from a friend I have decided to chuck them out. It seemed a bit dangerous that they just plugged straight into the 240v wall with no "Tranny" (or something) - And I don't know enough to re-wire them for LED's or anything, let alone put them in my daughters room :wired:

    Cheers,
    Komm
     
  15. TMM

    TMM Member

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    If you wire 20 identical bulbs in series to 240v each one gets 240v/20 = 12v. Seems safe, right? Where things go wrong is that globes are effectively a short circuit when they are cold/off, so if you pull a globe out and stick your finger into the open socket you may receive a 240v shock.

    As long as the replacement globes/leds are designed for the same voltage you should be fine - although you can probably get a whole string for less than it would cost to buy replacement LEDs.
    LEDs are actually safer in a transformerless configuration because they ensure that the voltage on an open socket is never much above the design voltage.
     
  16. 2xCPU

    2xCPU Member

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    Ok. By "plugpacks", I assumed you meant something that plugs into the wall - I've seen 24VAC, but not higher. (Thinking about it, I've got a 115VAC @15mA plugpack, but that's not very helpful either).
    I quite liked the suggestion of using LEDs. I did assume you meant 3/5mm LEDs and not something that would floodlight the room - wide angle or very wide angle 5mm would suit well.
    As for the PSU, you'd need to select the voltage based on Vf(of the LED chosen) x n (n = however many sockets in the string).
    Now comes the current calculation: n LEDs, 25mA per LED (wired in series) equals ....mA for the full string.

    Really, it is pretty easy and kinda fun.

    2.
     
  17. OP
    OP
    Kommandant33

    Kommandant33 Member

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    My fingers are far too big to fit in, but my little girl's are about the right size :wired: and she is the one who doesn't know better.
     
  18. RobRoySyd

    RobRoySyd Member

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    Where things go wrong (fail to meet Australian standards) is much simpler than that. Coming out of the mains plug are two conductors and one of them is at 240VAC potential relative to earth. It also is almost certainly not double insulated which means it can easily fracture leaving an exposed conductor that has a potentially lethal voltage on it. All that stands in the way of a fatality is the possibility that the house if fitted with RCDs.

    See above, that is just plain wrong. The voltage across the LEDs is largely irrelevant, the voltage relative to earth is the bigger concern.
     
  19. TMM

    TMM Member

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    Yeah, it's not exactly compliant with standards nor foolproof, but christmas lights have been set up like this for decades.

    I didn't say that a string of LEDs on 240v was safe (or legal), just safer than incandescent light bulbs. The probability of electrocuting yourself between an open socket and neutral (which is physically far away, say ~30 leds for 100v) is low. Doing the old 'which damn LED is not seated properly' is unlikely to get you electrocuted.

    You are exposed to much greater danger changing a 240v lightbulb in the ceiling, and that's a completely legal installation.

    Just use logic - turn it off before exposing yourself to live contacts.
     
    Last edited: May 22, 2013
  20. RobRoySyd

    RobRoySyd Member

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    Fixed it for you I believe. They're no more, well no longer sold retail in this country if for no reason other than a few people were killed by them. Needless death is never a good thing but even worse having a family member killed by a Christmas tree.
    The combination of poorly insulated 240V wires and lamp sockets and trees made of tinsel were a fatality waiting to happen.
    Here's a list of Christmas lights recalled just from Big W last year http://www.recalls.gov.au/content/i...52743880015b7f6f7&fn=Identifying Features.pdf
     

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