Touch Sensitive Sign Alarm

Do you have a sign that people keep stealing? Deter them from stealing said sign with the Touch Sensitive Sign Alarm!

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Step 1: Materials

1. Arduino (or equivalent)

2. Breadboard

3. Wires

4. Transistor (5V)

5. Resistors (1kOhm, and 330 Ohm)

6. Piezo alarm

7. Aluminum foil tape

8. Duck tape

9. One metal sheet (Make sure it is conductive)

10. Vinyl cutter

Step 2: The Sign

Take your metal sheet and test its conductivity throughout the area on either side. Next, choose one side to display your warning message. I included the file I used below. I cut this out using a vinyl cutter but I'm sure there are other, equally effective ways of cutting out your message.

Step 3: Building the Circuit

I have included a Fritzing Schematic of what the circuit should look like above. Notice the green wire in the bottom right corner. This will be taped to the sign with the aluminum tape. The vertical resistor is the 1kOhm resistor while the horizontal is the 330 Ohm resistor. Once the circuit is connected properly, attach the Arduino, breadboard, and alarm to the side of the metal sheet not covered by the words. Make sure to cover up the bottom of the Arduino and breadboard with an insulator to prevent problems with the circuit.

Step 4: Arduino Code

Here is the code I used for the Arduino:

#include // Include the Capacitive Touch Sensor Library
CapacitiveSensor sign = CapacitiveSensor(8,11);

int led=13; void setup() { Serial.begin(9600); pinMode(led, OUTPUT); }

void loop() { long touch = sign.capacitiveSensor(30); // Serial.print(" "); Serial.println(touch); if(touch>100){ Serial.println("Touch!"); //this value can change so do some testing first digitalWrite(led, HIGH); } else{Serial.println("No Touch!"); digitalWrite(led, LOW); } }

The if(touch>100) value can vary depending on a variety of circumstances so be sure to test the serial monitor values first. Once this code has been uploaded, connect the Arduino to a power source and your sign should be functional!

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