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Birthday Cake Candles LED

Discussion in 'Special Effects' started by verschleierung, Feb 15, 2019.

  1. verschleierung

    verschleierung Member

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    Location:
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    Hey Folks,
    I am mounting the show Crimes of the Heart and have just been told (the week before tech) that open flame will not be allowed without a fire-watch from the local FD (I should have known this, but hoped the College had an internal training).
    The scene "requires" that 30 birthday candles be lit individually while the cake is on stage.

    I have been created led birthday candles using straws and a large drop of hot glue on top with the led inside the drop.

    I need a controller to:
    1) have the candles light on-demand remotely
    2) have the flicker when they are on.

    Any ideas, suggests, jests, belittlement, or burlas are aprecciated!!

    Thanks,
     
    RonHebbard likes this.
  2. sk8rsdad

    sk8rsdad Well-Known Member Premium Member Fight Leukemia

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    It's probably too late now but the easiest technology for this would be LED pixel strings (WS2811, W2812, etc) and a wireless transmitter-receiver pair. It would give you individual control of each pixel via DMX or ACN. There are commercial offerings for this. Since you've already got LEDs the challenge is going to be finding a controller for your 30 individual "dumb" LEDs.

    The cheapest option might be an Arduino running a pre-recorded sequence. While it would be possible to trigger the sequence remotely, it just as easily be accomplished by a switch on the cake. A simplified example of how this could be wired up is here: https://learn.adafruit.com/adafruit-arduino-lesson-4-eight-leds
     
    RonHebbard likes this.
  3. ChrisB_SanDiego

    ChrisB_SanDiego Active Member

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    Location:
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    What about using a battery powered 32 channel DMX decoder with wireless dmx?

    Donner 2pcs DMX512 DMX Dfi DJ 2.4G Wireless 1 Receiver with Light Dome & 1 Transmitter Stage Lighting Control
    by DonnerDirect
    https://www.amazon.com/dp/B00HWM7H1E/?tag=controlbooth-20

    32 Channel 96A RGBW DMX 512 LED Decoder Controller DMX Dimmer DC5-24V RGBW RGB LED light 8 Bit/16 Bit
    by Colorful-USA
    https://www.amazon.com/dp/B075FHJM35/?tag=controlbooth-20

    Tenergy NiMH 24V 2000mAh Rechargeable – ‘Dumb’ Battery Pack
    https://www.all-battery.com/AT-NiMH-24V-11803.aspx
    unfortunately with chatting with them, they discontinued the charger for that model so you'll have to either find one elsewhere or go with a different battery pack. :-(

    You would also need 5v DC for the wireless DMX reciever.

    You might be able to use a powerbank but a lot of them have smart disconnects that don't work if there is not a specific load on them.

    Instead of using LED tape. You wired each led to v+ + color.
    ex.
    LED 1 to OUT 1 v+ and r
    LED 2 to OUT 1 v+ and g
    LED 3 to OUT 1 v+ and b

    patch it as a 32ch dimmer.

    You would want to meter the output of the decoder at max prior to hooking up the LED and accordingly put a resister in line to protect the LED. and even if you put 3 LED's in line and only have 10 channels that might still get you usable results.

    It's a bit of work. But You can get the parts quick.

    Good luck.
     
    Butch! likes this.
  4. JimOC_1

    JimOC_1 Member

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    Location:
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    Do you need control, the store-bought ones go out when you blow on them.
     
  5. alich

    alich Member

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    Location:
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    Probably too late for you to implement this, but I would vouch for an LED decoder system running off a 10aH 12V battery, using grain of wheat lamps for the candle flames.
    Those bulbs are about the size of a candle flame, and if you're lighting the scene right you won't see the tiny envelopes from the house.
     
    RonHebbard likes this.
  6. jonliles

    jonliles Well-Known Member Fight Leukemia

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    Location:
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    so what did you do?

    Simple would have been flickering LEDs, correct resistor, micro switches, and a battery. I can't reme,ber if the flickering LEDs need constant voltage or constant current. Both power supplies can be made cheaply.

    Rule of thumb, a coin cell battery CR2032 has enough internal resistance that you don't need the resistor - but that is a lot of CR2032s!
     
  7. verschleierung

    verschleierung Member

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    Location:
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    Hey Folks, because this was sprung on us at such a late date, we didn't have time to do anything fancy. Below is our solution:

    -Cake constructed of two layers of 2" rigid polystyrene with void beneath for wiring.
    -Four strings of AA battery-powered Fairy lights used.
    -Power switch on battery pack exposed for actor-control
    -Candle body made from paper drinking straws
    -"flame" was an exposed led in a drop of hot glue
    -cake was 'frosted' with quick-drying latex paintable caulking spread with a frosting knife
    -real cake was used in a small section for actors to eat and was replaced and frosted each perfromance.
    -Student piped the cake with real frosting.
    -Fondant roses made by student and were reused each performance to justify the void of candles on the real cake portion.

    I have attached photos.

    I would LOVE any feedback for future. Outside of the possible FX, I am calling this one a win!

    This project was shaped by yours-truly but executed by our student props designer, Devan. She saved the day!
     
  8. jonliles

    jonliles Well-Known Member Fight Leukemia

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    Looks great! Definitely a win.
     
    RonHebbard likes this.
  9. seanandkate

    seanandkate Well-Known Member Fight Leukemia

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    Occupation:
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    Location:
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    Very nicely done! And Gold Star, Devan!
     

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