Connie: Hey Hans, what are you doing?

Hans: Hi, Connie.  Well, as you know I am a 555 timer IC, so I’m pretty good at sending pulses of electricity in perfect time. Normally, I can blink an LED once per second but for some reason, I can’t make this high power LED flash.

Connie: Oh - you probably just need to give it more electrical current.

Hans: Hmm - you may be right.  but I can only supply a bit of current from my pins here, my integrated circuit was not designed for driving a lot of current.

Connie: Well, you are mighty lucky I came along — I can help you!

Hans: Really? How?

Connie: I may be small, but I’m pretty strong! I can push and pull ten times as much current as you can, and manage enough power to light this big LED - I just need you to tell me when to turn it on.

Hans: Oh? how do I do that?

Connie: Grab my hand like this –

Connie: So now, you just send electrical pulses through your output pin like you were doing before.

Connie: My other pin is connected to the positive leg of the LED, and all three of us are connected to ground.

Connie: Whenever you send an electrical pulse to my left pin, i’ll know you want me to do the same on my right pin. What I mean to say is - when you turn your pin on, I’ll turn the high power to the LED on.  And when you turn your pin off, I’ll turn power to the LED off.

Connie: You ready?

Hans: Ok, ya - let’s give it a go!

Hans: It’s working!  Connie - you *are* very strong!

Connie: Ha - just doing my job!  I’m a MOSFET :)

Hans: You have Mossy Feet? What in the wide world of sports is that?

Connie: Oh, no Hans - a MOSFET.  That stands for Metal Oxide Semiconductor Field Effect Transistor.

Connie: I can take weak electrical signals and strengthen them. Those small signals can then control much larger amounts of current.

Connie: I use three connections to make that happen.

Connie: My Source pin connects to the source electrons I want to control the flow of, such as ground or negative connection on a power supply.

Connie: My Drain pin connects to a positive power

Connie: … and my gate pin connects to the signal which tells me when to turn the higher current connection on or off.

Hans: So, you empower smaller electrical signals to make them bigger!

Connie: That’s true! You know - some folks even call me an amplifier.

Hans: Connie, the amplifying MOSFET - sounds like a superhero!

Connie: Ha - thanks, Hans.  Well, I told Cappy I’d meet him at an audio circuit around 2:30. He wants help to make his stereo speaker louder. Sooo - how long do we have to flash this LED for?

Hans: Oh - just like another 400,000 milliseconds. So, you should be fine.

Connie: Ohh … OK.

This guide was first published on Dec 12, 2017. It was last updated on Dec 12, 2017.
This page (Transcript) was last updated on Sep 12, 2020.