Easy Bluetooth Enabled Door Lock With Arduino + Android

Step 3: Assemble The Circuit

The diagram shows how the transistor is wired up in our circuit. As you can see, we have a diode pointed away from ground that is connected to the collector of the transistor as well as the ground of the lock itself. This diode will protect our electronics from any back voltage that might be created when our lock is turned off. At this point you could set pin 9 to high or low to control the lock.

Comments

[danica17]

what are those grounds? ground of power supply?

[stormdead]

I want to make this device but... i want a button activate the lock....

I'm using a 9v battery instead of a power supply


Is this ok?....:

int buttonPin = 2;
int ledPin = 13;
int lock = 9; //pin 9 on Arduino
int buttonState = 0;


void setup() {
pinMode(lock, OUTPUT);
pinMode(buttonPin, INPUT);
digitalWrite(lock, HIGH);
pinMode(ledPin, OUTPUT);
}

void loop(){
buttonState = digitalRead(buttonPin);
if (buttonState == HIGH) {
digitalWrite(ledPin, HIGH);
digitalWrite(lock, LOW);
delay(5000);
}
else {
digitalWrite(ledPin, LOW);
digitalWrite(lock, HIGH);
}
delay(500);
}

[stormdead]

Hi!... Where is connected the GND of the Power SUpply?

[Geniusdude]

How many mA is the power supply used here?

[Collin Amedee]

Well I am using my universal power supply from my first tutorial so it's doing somewhere around 20 Amps. These electric door locks only require about 125-200 mA

[Geniusdude]

Awesome. Glad to see another teen enthusiast btw.

[Collin Amedee]

Definitely! Don't forget to note for this in the Arduino contest!