Cecilia Elguero Parsons MFA Desing and Technology Thesis cecilia.elguero@gmail.com

## :::prototype 3:::

This is an implementation prototype that test the force and proper working of the circuit of the Nitinol wire. A potentiometer controls the amount of current given to the wire.  The little face rise up as current is ran through the Nitinol wire and goes down as no current is been run through it.

:::Nitinol circuit dagram:::

Nitinol wire (nickel + titanium) is a memory shape alloy that, when a current it is run through it, it remembers its original shape.

:::Process:::

In order to make Nitinol Wires go back to their original shape, a voltage higher the 5v (voltage output from Arduino Deicemille)  is needed.

I utilized a variation of the Using a transistor to control high current loads with an Arduino tutorial from the ITP Physical Computing site.

Here is a list of parts for the circuit:

1. Potentiometer

2. 10k Ohm resistor (in this circuit I used 2 4.7 k resistors instead)

3. TIP120 Transistor

4. 9v battery (connected directly to the bread board)

6. Nitinol wire

7. Jump wires

Nitinol wire: can be purchased here

The code is pretty much the same as the one that appears in the ITP tutorial except for some minor changes. Here it is:

int potPin = 0;           // Analog in 0 connected to the potentiometer
int transistorPin = 9;    // connected to the base of the transistor
int potValue = 0;         // value returned from the potentiometer

void setup() {
// set  the transistor pin as output:
pinMode(transistorPin, OUTPUT);
}

void loop() {
// read the potentiometer, convert it to 0 – 255:
// use that to control the transistor:
analogWrite(9, potValue);
}

Using a potentiometer to control the voltage going to the wire allowed me to observed the behavior of the wire within a range of voltages.