20 LEDs

Discussion in 'The Projects Forum' started by vickyobee, Sep 23, 2014.

  1. vickyobee

    Thread Starter New Member

    Sep 23, 2014
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    0
    Hello Every 1

    This is my First post ( so pls forgive if i make a mistake )

    I would like some help here pls

    I am planning to connect 17 LEDs in SERIES ( 12 V , White ) to my 220 VAc mains
    Can you pls point me in the right direction

    Many many thanks
    Vicky
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,440
    3,360
    Sorry.
    Yes, you did make a mistake.
    In the interest of safety we do not encourage discussion of direct connections to AC mains without proper use of a transformer.

    Hope you understand.
     
  3. vickyobee

    Thread Starter New Member

    Sep 23, 2014
    4
    0
    Thanks
    But will it not be possible to connect 1N4001 bridge and get it working

    And a transformer as in ???

    So what do you suggest
    How do i go about this
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    It is OK to discuss powering LEDs from the mains, but there MUST be an isolating transformer in between the mains and the project.

    You say your LEDs are 12V. What does that mean? Individual LEDs are typically ~3V each. They add when connected in series, so with 12V you might have 4 in series. I don't see how you could put 17 in series and get 12V.

    Are you perhaps hoping to put 17 devices that require 12V in series adding up to over 200V?
     
  5. vickyobee

    Thread Starter New Member

    Sep 23, 2014
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  6. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    You could power those all in parallel using a 12V DC power supply, such as one pulled from an old computer. Or you could make your own if you have a suitable transformer.

    Do you know how much power or current each one of those "bulbs" requires? That listing doesn't seem to say.
     
  7. vickyobee

    Thread Starter New Member

    Sep 23, 2014
    4
    0
    Frankly
    Have no idea
    But yes the Comp SMPS 12 volts is a VERY gr8 idea

    Thanks for the suggestion
     
  8. wayneh

    Expert

    Sep 9, 2010
    12,103
    3,038
    I recommend playing with one of those bulbs and a car battery, and measure the current draw with your multimeter. Start with the 10A mode and place the leads in series with the bulb. Don't apply the leads in parallel like you might normally. That will immediately blow the fuse in your meter (if you're lucky). If the current is less than 0.2A, you can switch to a lower current scale to get a more precise value. Your meter may have different ranges, but it's the same idea; start high and move down.

    Once you know the current you need, it'll be much easier to come up with a safe solution.
     
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