The useless alarmed Coke can using Arduino
This is the most useless project in the world! It consist in a Coke can attached to an Arduino trough a coaxial cable and two resistors that make a sound when an hand is near it.
Step 1: Materials and Tools
For make that I’ve used:
-1x Arduino Uno Board (or equivalent)
-1x 270kOhm resistor
-1x 10kOhm resistor
-1x alligator clip (not in the photo)
– a piece of coaxial cable
– a short wire
-1x Piezo speaker
-1x rubber band (optional)
-1x full Coke can (not an empty one!)
-1x beer coaster
-2x A4 sheets of printer paper
– tape (of any sort, for example I’ve used insulating tape)
– glue stick
– fibre pen (not in the photo and optional: it’ s for making the sign “FREE COKE”)
– soldering iron with relative tools (not in the photo)
Step 2: Empty the can
Take the can and, carefully, make a little hole on the bottom of it with the scissors. Let the gas come out and enlarge the hole. Then make an other one hole and make out the liquid in a glass. This is a VERY long process so be patient.
Step 3: Make the circuit
How I’ve seen here, the human body is grounded, so the aluminum of the can and your hands make a sort of capacitor that has more capacitance as your hand is closer to the can.With Arduino we can know the time of charging of the “capacitor” and so the distance between the hand and the can. For make that, as you can see in the picture, we need a 270kOhm and a 10kOhm resistor, a coaxial cable and an alligator clip for connecting the Arduino to the can and a Piezo speaker for making sounds when an human body part is near the can. The making of cable for connecting the can with Arduino will be explained in the next step. For now connect only the positive(+) pin of the speaker to A0 on Arduino an the negative(-) to GND(Ground) (As you will see in next steps, i’ve added the rubber band for fixing the speaker to Arduino but it’s mainly useless: it’s an optional)
Step 4: Make the cable
As first step you must solder one terminal of the 10kOhm resistor to the internal wire of the cable (Picture #1). Then solder the 270kOhm resistor to the internal wire where is soldered the 10kOhm and to the external shield (Picture #2 and #3). Solder to the external shield, where is the 270kOhm, a wire that will be linked to 5V pin on Arduino(Picture #3). On the other side of the coaxial cable solder the alligator clip to the internal cable (be careful to don’t connect the external shield to the clip!!). If you want, you can put an heat shrink tubing on resistors and clip as I’ve done (Picture #4). Picture #5 shows the structure of a coaxial cable.
For more detail: The useless alarmed Coke can using Arduino
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