Fork me on GitHub

Project Notes

#066 Digital Logic Switch - N-Channel Enhancement FET

Using a small-signal n-channel MOSFET as a switch, with turn-off delay.

Here’s a quick video of the circuit in action:

SwitchNFET demo

Notes

N-Channel Enhancement FETs are easy to use as a digital switch:

  • ON when gate-source voltage is much greater than threshold voltage (into saturation region)
  • OFF when gate-source voltage is below threshold voltage (0.8-3V for 2N7000)

This circuit demonstrates the basic switch, with the addition of a turn-off delay.

The turn-off delay is implemented with a simple RC circuit: the R1=220kΩ C1=10μF pair having a time constant of 2.2 seconds.

Construction

The Breadboard

The Schematic

The Build

Credits and References

About LEAP#66 MOSFET
Project Source on GitHub Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.