Science Buddies: "Ask an Expert"

Hi team
This is Peter. My question is about the Potentiometer connection in the breadboard in DIY Mini Drone: Altitude Control Circuit and I have attached the screenshot. In my opinion, the connection should be only two probes not three. Can anyone explain why it is the case. Also, can someone explain how does the Mosfet work
Regards
Peter.

Hi Peter,

When all three terminals of the potentiometer are connected like that, it forms a variable voltage divider. The voltage on the middle pin (green wire) changes between 0V and 5V as you turn the knob.

The MOSFET is a type of transistor, which is like an electronic "valve" to control the flow of electrical current. A MOSFET in particular is a "voltage controlled" valve meaning you need to vary the voltage at its input pin (as opposed to a bipolar junction transistor, or BJT, which is "current controlled").

So by using the potentiometer to vary the voltage sent to the MOSFET, you control the amount of current flowing through the motors.

I hope that quick explanation helps. If you'd like more detail, we don't have our own in-house tutorials on voltage dividers or transistors at Science Buddies, but if you search YouTube there are many good videos that explain how they work in more detail.

Thanks,

Ben