Experiment 6
Now you know everything there is about series and parallel circuits, bulbs, and cells and batteries! Well, you know as much as you need for this challenge. Here is something I made from my Christmas light string:
You may not be impressed, but I thought it spectacular for 10 minutes of work. I'll show you how I made mine and you can create any design you wish with your extra lights.
STEP 1. Decide on your design. What shape do you want to display? Draw on a piece of thin cardboard and mark where you want the lamps to show. Use a hole punch or pencil to make a hole big enough for the bulb.
STEP 2. Determine how many bulbs you need.
STEP 3. Remember that each bulb needs to see between 2 and 3 volts to be bright enough. Let's say you have a need for 20 lights. That means you could apply a voltage of 48 volts...but, no one has 48 volts handy! I wanted to make my sign not depend on batteries so I found an old power converter. On the label it said, 5 Volts. That means I could run two bulbs in series. So, here is the circuit I made:
Each pair of bulbs "sees" 5 volts and then divides it in two so each bulb has 2.5 volts. Perfect! Putting the pairs in parallel means one power supply can light all the cells.
Find what power supply you want to use and calculate how you will arrange the bulbs. If you have a 12 volt source you will want to have series sets of 4 or 5. If you have a 9 volt source, then you can put 3 or 4 in a series.
STEP 4. Wire the contraption! Trace your wires so that your circuit matches the diagram you have made. This can be a bit frustrating so you may want to place a small piece of masking tape on one end of each pair, triplet or quad so that all these wires will be spliced together.
Here are two examples of what you might do with your lights. Here are lights arranged to form the number "8" digitally. I covered the glued strips of foam with some acetate sheeting or plastic. You could use this to put your house numbers in lights!
In another experiment, I added a switch for each lamp. This way I can "program" which lights can be lit. Each switch is in series with a bulb.
Design your own. What is the worse thing that could happen? You could burn out some bulbs...they are already from a bad string and there's probably more where that came from! If you short your power source it could damage or ruin the power supply, so if that worries you, use batteries. Remember you can make any voltage you want in increments of 1.5 volt cells!
What's the best thing that could happen? Your friends think you are a genius and want you to make them their own name in lights!
RETURN TO 10 EXPERIMENTS WITH A DEAD STRING OF CHRISTMAS LIGHTS
