2N7000

The 2N7000 is an N-channel, enhancement-mode MOSFET used for low-power switching applications.

[1] The 2N7000 is a widely available and popular part, often recommended as useful and common components to have around for hobbyist use.

Packaged in a TO-92 enclosure, the 2N7000 is rated to withstand 60 volts and can switch 200 millamps.

A typical use of these transistors is as a switch for moderate voltages and currents, including as drivers for small lamps, motors, and relays.

[1] In switching circuits, these FETs can be used much like bipolar junction transistors, but have some advantages: The main disadvantages of these FETs over bipolar transistors in switching are the following: Many other n-channel MOSFETs exist.

The 2N7000 is housed in a TO92 package, with lead 1 connected as the source , lead 2 as the gate , and lead 3 as the drain . The BS170 has the source and drain leads interchanged.
The 2N7002 variant is packaged in a TO-236 surface-mount package.