Play the Room — First Class

Play The Room had its first class last week!  Having solidified the roster, we broke out the solenoids and, well, played around with them.

In order to better get to know the solenoids, we hooked them up on a breadboard, as shown.  The mosfet shown acts like a switch, controlled by the arduino through pin 11 in this schematic.  When the program in the arduino tells pin 11 to go HIGH (+5 V), the mosfet allows current to flow through the other two leads, providing the solenoid with a path to ground.  Current then flows through the coil of the solenoid, and the metal core inside it is forced outward, striking whatever may be in its path (percussion!).

When pin 11 goes low, as determined by the Arduino’s software, current ceases to flow through the other two leads of the mosfet, therefore no current flows through the coil of the solenoid.  This means there is no longer a magnetic force pushing its metal core outward, allowing it to return to its internal position.  However, the solenoids we ordered to not have a spring to make the core return to its starting position, and one cannot simply reverse the direction of the current through the solenoid’s coil and expect a magnetic force in the opposite direction (http://en.wikipedia.org/wiki/Right-hand_rule).  Our (hopefully temporary) solution was to use a rubber band to bring the core back to its starting position.

By the end of the class, the solenoid cacophony had drawn a small crowd.  Check it out!

http://www.youtube.com/watch?v=bisMUvgiogU

Here is the arduino code:

//***********************************
int solPin = 11;

void setup() {
pinMode(solPin, OUTPUT);
}

void loop() {
//give the mosfet a voltage pulse to activate the solenoid
digitalWrite(solPin,HIGH);
delay(30);
digitalWrite(solPin,LOW);

//wait one second
delay(1000);
}

//***********************************

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