For many years I stuck to only using NPN transistors for all my transistor needs. I’m not sure why but I guess subconsciously I thought MOSFETs were going to be complicated to use.

That’s SO FAR from the truth! MOSFETs are super easy to use.

To turn it on, simply connect a voltage directly to the gate. Once you’ve done that, current can flow freely from drain to source.

Below I’ve created a complete example with a pushbutton that will turn on the transistor when it’s pushed, which will turn the LED on:

The 1k resistor is there to limit the current to the LED. But what about the 10k resistor?

Without this resistor, the mosfet will never turn off again after the button is released!

Here's why:

The 10k resistor is a pull-down resistor. It's there because the gate also acts as a capacitor. When you release the button, if you don't have this resistor, the gate will be "floating" and just stay at it's current voltage, leaving the transistor on.

But with the pull-down resistor, the capacitor gets discharged as soon as you release the button so that the transistor turns off again.

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Connecting that circuit using components would look like this:

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Build a few circuits using the mosfet as a switch that controls something, and you'll soon get the hang of it and see that it's easy to use ;)
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Keep On Soldering!
Oyvind @ build-electronic-circuits.com

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