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Help in making LED lamp

Discussion in 'Electronics Homework Help' started by pharaon, Jul 7, 2015.

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  1. pharaon

    pharaon

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    Oct 28, 2014
    is there any tutorial on how to make Led lamp work on 250 V without adapter
    like in this video
     
  2. Gryd3

    Gryd3

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    875
    Jun 25, 2014
    nope.
    Maybe for a specific lamp. They are built too differently to give a step by step on how to do this. Additionally, if you are not familiar enough with the process to do it yourself, then you should not be doing it.

    Modifying mains powered devices is a fire hazard and should not be done by beginners or amateurs.
     
  3. Martaine2005

    Martaine2005

    3,996
    1,084
    May 12, 2015
    I agree with Gryd3 whole heartedly.
    But there is a way. Many 'silly' designers/artists are making their own mains/rectified lamps.
    They do work but are extremely dangerous at the very least.
    Other countries do not see 'our' health and safety or danger as being serious.
    My brother in-law used to hang his washing on the 110v coming in.
    Different world and different appreciation for electricity and dangerous it can be.
    On a side note, I was in Ecuador for a month and the shower was cold.
    My brother in-law hooked up a water heater directly to the 110v lines above his apartment....
    Needless to say, the cold shower was perfect!!!!

    Martin
     
  4. pharaon

    pharaon

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    Oct 28, 2014
    i mean what was the idea to make this led work on 220V without adapter
     
  5. Gryd3

    Gryd3

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    Jun 25, 2014
    I don't speak the language so I can't tell you.
    Smart designers will usually build the device so that it's 99% complete, and a simple jumper, or swapping a single component will allow the device to be used on 220V or 110V. Without knowing what he is saying, I have no clue as to what he may be suggesting you do.

    If the device is designed for that purpose, it can be done quite easily. If the device is not designed for this, then it will require a 'hack' of some sort to make it work. In either case, I still suggest you don't attempt it.
    Look for a bulb rated for your local voltage, or a universal bulb that can operate from 100-240V.

    Sorry, but I won't be sharing any further information on this. I've already had a close call from someone thinking they knew what they were doing with mains wiring.
    I've seen dollar store extension cable installed in a wall where the insulation was dried and literally flaking off like dust. I've had an aunt get shocked when she touched the stove and fridge at the same time, and I've gotten not just a nasty zap from a shop dust collection unit that had no ground, but also had to deal with al electrical fire caused by using a plug that was not rated for the current the device was pulling. You know how you get that little spark sometimes when you plug something in? Well, apparently this spark never stopped and by the time I got to it half the plug was eroded or melted in the socket. (It sure 'looked' like the right plug, but you need to pay attention to fine print) Needless to say, I no longer work in this shop. Dealing with those problems is above my pay-grade.
     
  6. pharaon

    pharaon

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    Oct 28, 2014
    i was just trying to understand the idea not to create one

    i can tell what he was saying in the video

    he says the earlier led lamp had adapter which cause some heat but in this one it doesn't have adapter at all..all what it contain is some Led and 4 diodes and two resistance and two capacitor.he says this are responsible about making AC to DC but i can't see any thing to convert from 220V to 12V. maybe how they put the Led around is what convert from 220V to 12V

    that is what he saying in the video
    is what he's saying true
    is the way how the Led are connected make 220V to 12 V
     
  7. Gryd3

    Gryd3

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    Jun 25, 2014
    Well.. this will vary a lot depending on the manufacturer...
    Cheap LED lamps like the above will use 4 diodes as a bridge rectifier to convert the AC to pulsed DC. A Capacitor will smooth this out to eliminate flickering of the LEDs.
    There are 30 LEDs on the bulb in the video... it's hard to tell exactly how they are wired. but considering there are two resistors, I would assume that the LEDs are wired into two sets of 15. which would mean the voltage required would need to be at least 50V for the LEDs.
    The second capacitor may be wired in such a way that it's in series with the rest of the circuit, if tuned correctly, this will limit the amount of current passing through the circuit.
    If this is the case, not only is the voltage important, but the frequency is as well.
    To convert such a lamp to 220V, you would need to first confirm that this is indeed the designed mode of operation, then you would need to swap out the series connected capacitor for one that is correctly sized to limit the current when used on a higher voltage. Unfortunately, I have very limited experience with this type of circuit and am not comfortable offering you any additional details in calculating it's value.
     
  8. pharaon

    pharaon

    395
    7
    Oct 28, 2014
    i start this long time ago, hope it's not closed yet
    i found something for led lamp without adapter
    want to know what do you think about it

    [​IMG]
     
  9. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    It's very difficult to see the schematics... they are very small...
    That said, I don't like any of them.
    The top left looks like a transformerless power supply. You do realise they can be quite dangerous to work on because they are not isolated from high voltage. Because of this, many people here will reject or ignore any help in building one.
    You best solution is to either buy an adaptor or build one that uses a transformer.
    Additionally, the led layout in the bottom right is far from ideal... when you connect LEDs in parallel without resistors you run the risk of damaging them. LED's have a forward voltage *range* ... so if one branch of a parallel circuit has a lower combined forward voltage, it will pull much more current than the other branches which could cause damage... once this branch is dead, your circuit will still be pushing enough current for *all* the branches even though one has died. This will lead to the remaining branches being stressed eventually resulting in all branches failing.

    - Build or buy a transformer based adaptor.
    - If you connect LEDs in parallel, use one resistor on each branch to help balance the branches to avoid damage.
     
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