Things You'll Need:
- bread board
- 50 ohm resistors (at least 1)
- wires
- wire strippers (scissors are an effective substitute)
- 9V battery
- 9V battery holder/casing
- LEDs (up to 7)
- licorice strings
- Indian edible silver sheets
- chocolate (dark frosting-ed) cake
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Step 1
The final circuit for connecting LEDS on your cakeUsing the attached image, create the circuit on the breadboard to test the circuit before putting it on the cake.
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Step 2
9V battery holder couteousy of www.solarbotics.comUse the 9V battery holder/casing (the red wire is the +, the black wire is -). Connect the battery to one end of the resistor - it doesn't matter what side of the resistor.
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Step 3
Connect the other side of the resistor to the + side of the LED (this is the longer pin).
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Step 4
Connect the other side of the LED (the -, shorter pin) to the negative side of the battery (the black wire coming off the 9V battery holder)
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Step 5
Repeat Step 3 and 4 for each LED you want to add to the circuit. These LEDS will be in parallel. (Do not do add more than 6-7 LEDs to the circuit as the LEDs will not be as bright)
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Step 6
Test to make sure that the circuit works. Once this works, proceed to the next step.
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Step 7
l to r: finished wire, raw licorice rope, wires in process, edible silver sheetCreate the licorice wire. Use a large piece of saran plastic wrap as your work area. Place a sheet of edible silver (usually a very thin 3"x3" sheet) on your plastic wrap work area. Put licorice rope (very thin) on this silver sheet and roll with your fingers to thoroughly cover the rope (the better you cover the wire, the better conductor of current on your cake).
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Step 8
Put two strands of the licorice rope in parallel on the cake. But do not let the two strands touch! One is your + and one is your - ground.
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Step 9
Place your LEDs across the two parallel licorice ropes. Make sure the + end of the LED (the shorter pin) is touching the + wire and the longer pin (- side) is touching the other wire. The LED completes the circuit.
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Step 10
Using the tested breadboard circuit, connect the wire coming out of the resistor to the + licorice rope. Poke the wire coming from the resistor into the silver-coated + licorice rope.
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Step 11
do not forget to power both sides of the + wire!
Poke another wire from the resistor into the other end of the silver-coated + licorice rope. Since there is a lot of current lost along the licorice wire, those LEDs farthest from the power source are not as bright. By powering up both ends of the + licorice rope, you can provide juice to both ends and achieve better LED brightness.
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Step 12
Poke another wire into the - licorice rope and connect that to the - terminal of power (to the black wire coming off the batter holder). You should see the LED light up.
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Step 13
repeat step 9 for each of the additional LEDs. It should look like a ladder of LEDs.
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Step 14
a child's science-themed, LED birthday cakeTurn out the lights in the room and prepare for a dramatic entrance. Make sure it is dark as it makes the LEDs that much more impressive.
