The MOSFET transistor is an easy way to allow your Arduino or other micro-controller to handle voltages larger than the 5 volts available for each pin. It's really helpful knowledge if your ever wanting to drive something that requires significant more power than a micro-controller can provide. I'm using it to control some 12 volt LED strips. I have also used it to control a salvaged windshield wiper motor. This simple circuit will open up more possibilities for your projects.
Step 1: Parts
- schottky diode
- a MOSFET transistor (here I used IRF510) be sure the MOSFET your using can safely handle the voltage that your project requires
- circuit board
- wire (three colors)
Step 2: Basic Wiring Steps
The MOSFET has 3 legs described as gate, drain, & source. Gate is the leg that receives the signal from the Arduino and is protected from the source voltage. Drain is the leg that is attached to both the power source (through a schottky diode) and what would normally be the ground connection of the device your trying to control. Finally the source leg connects to ground.
Step 3: Step by Step Wiring
Wiring this is relatively simple but for anyone who is just starting out I'll go through every step. First I strip the wire that will provide the power to the circuit. Placement is something that is important if your wiring several things to your circuit board. Here there is ample room for what I plan on wiring. Insert the wire into the board and solder. After that I insert the wire that will be for power to my device I also bridge the connection between these two on the circuit board. Then I bend the two ends of the schottky diode down and insert it into the board with the banded end away from the mosfet and then bridge the connection between it and the other power wires. Next I install the transistor on the board so that the middle leg (drain) is aligned with the un-soldered end of the schottky diode. The diode is soldered in place and the excess is trimmed off and the middle leg and the schottky diode are connected. Another wire is soldered in place next to this and connected to the prior connection, this will be what is normally the ground side of whatever your device is. A wire is soldered next to the source leg of the transistor and connected to it, this will be your ground connection. Finally a wire is soldered next to the gate leg of the MOSFET and connected to it, this wire is the wire that will go to the pin on your micro-controller that will communicate with the transistor.
Step 4: Connecting to Power, Arduino, and Device
It is a good idea to check all your connections with a multimeter and confirm that all the connections you've made are connected and that there aren't any connections that shouldn't be there. I usually, just to play it safe, check the circuit with something at 5 volts or less to minimize any possibility of ruining my micro-controller. Once your confident that everything is correct, your now ready to control higher voltage devices. The MOSFET can also be used for PWM, enabling you to slow down a motors speed or to dim lighting. The project that I'll be doing will need two MOSFET so another one will be wired onto this board as well.