Okay, so today I messed around with a D MOSFET, and let me tell you, it was a bit of a journey. I’ve played with regular MOSFETs before, but this was my first time specifically diving into the D-type.
Getting Started
First things first, I gathered my supplies. I needed the D MOSFET itself, of course (I used an IRF540, just because I had one lying around), a breadboard, some jumper wires, a power supply, a resistor (around 220 ohms, nothing fancy), and an LED. The LED is just to visually see if things are working, you know?
The Hookup
Wiring it up was pretty straightforward, at least in theory.
- I connected the Source pin of the MOSFET to the ground of my power supply.
- Then, I connected the Drain pin to the negative leg of the LED.
- The positive leg of the LED went to one end of the resistor.
- And finally, the other end of the resistor I wired to the positive of my power supply.
Now, the Gate pin is the control, the on/off switch. Initially, I just left it unconnected. With a D MOSFET, and this is important, it’s “normally on.” That means that without any voltage on the Gate, it should conduct, and my LED should light up.
The Test (and some Head-Scratching)
I powered it up, and… nothing. The LED stayed stubbornly dark. I double-checked all my connections, made sure my power supply was actually on (been there, done that!), and even swapped out the LED and resistor, just in case. Still nothing.
I grabbed my multimeter and started poking around. I had voltage at the power supply, voltage at the resistor, but very little voltage going through the MOSFET. It was like it was barely open.
The “Aha!” Moment
I realized something. My “bench” Power Supply is adjustable. I had forgotten to adjust it correctly. It turns out I need to provide a bigger Voltage to get it to conduct.
The Fix
I readjust my Power Supply to about 10 volts. I put my positive lead of my Power Supply to the Gate, and ground to the Source, and it worked!
My suggestion is start low, and work your way up. This is because I don’t want to destroy my D mosfet.
Final Thoughts
It was a good reminder that even simple circuits can have their quirks. It reinforced the importance of testing each part of the circuit and double-checking everything. Also, it was a solid hands-on lesson in how a D MOSFET actually behaves. Next time, I’ll try using it in a more practical project, maybe a simple motor controller or something.