IRFZ44N MOSFET LED Driver
Switch a 12 V LED strip from a 3.3 V microcontroller pin using a logic-level N-channel MOSFET.
Difficulty: Breadboard. Estimated build time: about 25 minutes. Estimated parts cost: about US$3.50. 4-line bill of materials. Compare supplier offers when available. A low-side MOSFET switch that lets a 3.3 V microcontroller pin (for example, a Raspberry Pi GPIO or an ESP32 output) turn a 12 V LED strip on and off.
Lay out the rails
On your breadboard, dedicate one rail to 12 V (from a wall adapter or bench supply) and one to ground. Tie the microcontroller's ground to the same ground rail — without a shared ground reference the MOSFET cannot see the gate signal.
Place the MOSFET
Insert the IRFZ44N (TO-220, leads facing you, label up). Pin 1 is gate (left), pin 2 drain (middle), pin 3 source (right). Connect source to ground.
Wire the load
Connect the LED strip's + terminal to +12 V. Connect the LED strip's − terminal to the drain (pin 2). The MOSFET sits on the low side, between the load and ground — this is the simplest and safest configuration for beginners.
Connect the gate
Connect a 220 Ω resistor between the MCU output pin and the gate (pin 1). Add a 100 kΩ pull-down from gate to ground. The 220 Ω limits inrush current into the gate's parasitic capacitance during switching, and the 100 kΩ keeps the MOSFET off when the MCU is unplugged.
Test and PWM
Drive the gate high from the MCU — the strip should turn on instantly. Drive it low — the strip should turn off cleanly with no visible afterglow. To dim the strip, write a PWM signal to the MCU pin (1 kHz works well). The IRFZ44N switches fast enough that the strip won't flicker, and stays cool enough that you don't need a heatsink for a few amps of load.