Okay, so today I messed around with MOSFETs, specifically looking at the drain, gate, and source. It wasn’t anything fancy, just wanted to get a better handle on how these things actually work in a practical sense.
Getting Started
First, I gathered my stuff. I had a few different N-channel MOSFETs lying around, I think they were IRFZ44Ns, but don’t quote me on that. Also grabbed my trusty multimeter, a breadboard, some jumper wires, a 9V battery, and a resistor (I think it was around 220 ohms, just to be safe).
Setting Up the Circuit
I started by popping the MOSFET onto the breadboard. Then, I connected the 9V battery’s positive terminal to the resistor, and the other end of the resistor to the drain of the MOSFET. I used a red jumper wire for this, just to keep things visually clear.
Next, I connected the battery’s negative terminal directly to the source of the MOSFET. Black wire for this one, again, for clarity.
Testing the Gate
This is where it gets a bit interesting. Initially, with nothing connected to the gate, I used my multimeter to check the voltage between the drain and source. It was pretty much the full 9V, meaning the MOSFET was “off” – no current was flowing.
Then, I took another jumper wire (a yellow one this time) and briefly touched it between the positive terminal of the battery and the gate of the MOSFET. Just a quick tap! After that, I checked the drain-source voltage again… boom! It dropped significantly, almost to zero. The MOSFET was now “on,” allowing current to flow.
Important Note: I didn’t keep the gate connected to the positive voltage for long. Just a quick touch to “charge” the gate. MOSFETs are sensitive to static electricity, so you have to be careful with that.
- The Gate is the Control: A small voltage on the gate controls the current flow between the drain and source.
- Drain to Source Current: When the gate is “charged,” current can flow from the drain to the source.
It was a simple experiment, but it really helped me visualize how the gate voltage controls the drain-source current. It’s one thing to read about it, but it’s another thing entirely to see it happen in front of you.
That’s the fun thing about hands on, it does’t have to be complicated to be useful.