A present for my girl. Help!

Discussion in 'The Projects Forum' started by Booocubs, Dec 11, 2011.

  1. Booocubs

    Thread Starter New Member

    Dec 11, 2011
    I am creating this cool (In my opinion) present for my girlfriend. From the picture I think you can tell we started dating on November 11th, 2009. I need your help guys!


    There is my project/present. There are 24 total purple LEDs, and the 14 red ones you see, I'm changing to 18.

    I'm going to be taking power from the outlet, providing 120v AC power. The voltage drop, as show in picture, should add up to 120v if wired in series. I was told this is a bad idea, to wire in series because if one led goes out, the rest won't work. How would you guys wire this? I'm not the best at electronics :(
  2. bertus


    Apr 5, 2008
  3. SgtWookie


    Jul 17, 2007
    You must use a transformer to isolate mains power from your project.

    I suggest using a "wall-wart" type of plug supply that is regulated; somewhere in the range of 10v to 25v. These can be obtained for far less money than a funeral.

    Here are a variety of "wall wart" type plug supplies from a vendor I've used a number of times:

    One of the 15v regulated or the 18v regulated would be just fine for your project.

    If you would like to try doing some light animation with your project (like a "movie marquee" effect), then stick with one of the 15v supplies; they will work fine with 555 timers and 4000 series CMOS logic ICs.
  4. wayneh


    Sep 9, 2010
    Not to pick nits, but if the OP used a commercial string of LEDs and stuck the LEDs thru the holes as he's drawn, would the mere construction of his enclosure really be prohibited?

    Now, I'll admit it might be impossible to find a string with the right mixed colors, and you probably can't swap bulbs between strings. So a moot point perhaps.

    No quibbles that putting this together from components would be a bad idea.
  5. Wendy


    Mar 24, 2008
    Construction of enclosure was not the issue. The issue is direct mains connection, nothing else. I'm not sure if you were arguing that or not, but we will not allow any dangerous shortcuts if it can be helped.

    I disagree with both of the above statements. You can mix and match LEDs to your hearts content, and individual LEDs are significantly cheaper. If the OP has questions we can help him with the design work.

    I've wired point to point with LEDs sticking through cardboard or wood. Soldering does take practice, but it is neither hard nor complex.

    A note to the OP, if you want to do this project, pay attention to the negative lead, the cathode. The eBook has a drawing on the subject, something I added a while back.

    Special-purpose diodes
    Last edited: Dec 11, 2011
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    Just having those LEDs stay on all the time would be boring.

    Have the 1's blink or chase each other, while the heart fades bright to dim (throbs) around twice per second.

    What I describe above isn't very much harder than soldering that many LEDs in the first place. Check out Bill Mardsen's blog for both the sequencing and the fade in/fade out.

    All of this could be done using 6V supply/4AA batteries.
  7. Wendy


    Mar 24, 2008
    Possibly, but I would wire them first, then modify them for special effects.
  8. magnet18

    Senior Member

    Dec 22, 2010
    for the 11's, maybe all off, then the first 11 lights up, then both, like
    __ __
    11 __
    11 11
    __ __

    and fade the heart maybe once per second
    that would look nice

    also, even if you were to hook the LED's up in series with no resistor, they might fry if Vf isn't just right
    and anything directly plugged into the wall gets closed around here.

    OH, and use a photosensor in the center of the heart to turn it on for a couple minuets or whatever when you touch it!
  9. wayneh


    Sep 9, 2010
    I meant within an LED light string; if your string is 30 blue LEDs (or whatever number they are), I don't think you can just sub in other colors. Gotta admit I never tried. Are you saying you can? I assumed your comments pertained individual LEDs.

    And on the "components" statement, I meant a mains-connected build from components would be a bad idea, and is not allowed here. I didn't mean it was a bad idea to use individual components WITH a properly isolated power supply. That'd be fine.