Nightlight Cat Bracelet

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WHAT WILL YOU MAKE?

In this project, you are going to make a cat bracelet that has a light sensor. This is the same type of sensor that is in a nightlight. This cat bracelet automatically turns on the lights in its eyes when it senses darkness.
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WHAT WILL YOU NEED?

STEP 1

Sketch all of the pieces of your bracelet on a felt sheet with a chalk pen.

STEP 2

Cut out each of the felt pieces. Make sure the piece of fabric that will function as the bracelet band is long enough to go all the way around your wrist with a bit of overlap so it can snap shut and that the bracelet is wide enough to hold the entire circuit.

STEP 3

Arrange the felt pieces on the long felt bracelet shape and glue them together according to your design.

STEP 4

Using an awl, or other sharp tool, carefully poke holes for the LEDs.

STEP 5

Mark the positive and negative holes on the felt with a chalk pen.

STEP 6

Push the legs of the LEDs through the holes you created in the bracelet so that the lights are showing on the front and the legs are on the back. Note that in these images, the lights of the LEDs are shown on the back for clarity.

STEP 7

With conductive thread, sew the positive legs of the LEDs together and then sew the negative legs of the LEDs together.

STEP 8

Carefully poke two holes for the light sensor with your awl.

STEP 9

Insert the sensor’s legs as you did with the LEDs. Again, make sure that the sensor is facing the outside of the bracelet and that the legs are on the inside. Unlike the LEDs, the sensor does not have polarity, so it does not matter which leg goes through which hole. Again, please note that the light sensor in the illustration is shown on the inside of the bracelet for clarity. As a result, you can’t see the legs in this illustration.

STEP 10

Draw the rest of your circuit on the back of the bracelet with a chalk pen.

The transistor can go on the inside of the bracelet, so you don’t have to poke holes for the legs, but make sure it is facing the correct way, as illustrated here.

STEP 11

Connect the transistor’s emitter and base to the legs of the light sensor.

STEP 12

Connect the collector of the transistor to the negative legs of the LEDs.

STEP 13

Connect one side of the resistor to the base of the transistor.

STEP 14

Glue a battery holder onto the bracelet. Make sure it is positioned with the negative side pointed toward the circuit. Connect the negative side of the battery holder to the transistor’s emitter and one of the legs of the light sensor. Connect the loose end of the resistor to the positive legs of the LEDs.

STEP 15

Attach a metal snap fastener to each end of the bracelet. Make sure they are on opposite sides of the bracelet. In the following illustrations, they are shown on the same side for clarity.

STEP 16

Connect one snap to the positive side of the battery holder. Connect the other snap to the connection between the resistor and the positive legs of the LEDs. These snaps will serve as a switch that turns the circuit on and off.

STEP 17

You’re almost done! Test the circuit by putting in a battery, closing the snaps, and covering the sensor. The eyes should light up.

STEP 18

After you make sure the circuit works, sew a small sheet of felt over the exposed circuit, to prevent your skin from touching the circuit, but make sure you can still change the battery.

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Please Note

Your safety is your own responsibility, including proper use of equipment and safety gear, and determining whether you have adequate skill and experience. Power tools, electricity, and other resources used for these projects are dangerous, unless used properly and with adequate precautions, including safety gear and adult supervision. Some illustrative photos do not depict safety precautions or equipment, in order to show the project steps more clearly. Use of the instructions and suggestions found in Maker Camp is at your own risk. Maker Media, Inc., disclaims all responsibility for any resulting damage, injury, or expense.

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