Does a Breadboard Compatible DC Barrel Jack Have to be Connected to Positive and Ground to Receive Power from an Outlet

breadboarddcpower

I am using an Arduino to control an electric lock strike but I don't know how to power the lock with sufficient power. To control the lock from the Arduino, I am using a TIP31 transistor (It is NPN). The transistor will be getting the signal from pin 9 on the arduino and will connect to the ground wire of the lock strike. Since I will only need the DC barrel jack for positive (since the ground wire of the strike will be connected to pin 9 via transistor), I need to know whether this barrel jack will draw power from a power source even though it will not be connected to ground.

P.S. The lock strike needs 12VDC.

Best Answer

Below is a basic schematic of how everything will be connected. V1 is the Arduino power supply, either 5V usb, or 7V to 12V dc barrel jack. V2 is the Lock Strike power supply. It will vary based on your lock strike, probably 12V to 24V. Regardless of the combination, the red wire below connects the grounds of both power supplies together (the DC, barrel jack side, not the AC wall side!). Just connect any ground connection on the Arduino to the emitter of the TIP31/ground of the lock strike power supply.

schematic

simulate this circuit – Schematic created using CircuitLab