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How to Connect to a MOSFET

A MOSFET -- Metal Oxide Semiconductor Field Effect Transistor -- is a semiconductor made from silicon. MOSFETs are primarily used for power switching; millions of them are placed inside of single chips used in computers, household appliances and power supplies.

MOSFETs typically have three leads: the drain, source and gate. The current flow inside them depends on the gate, which behaves like a voltage-controlled variable resistor. MOSFETs have a channel that conducts from source to drain, which is classified as either N-channel or P-channel (N is negative, P is positive). To connect to a MOSFET, attach its drain, source and gate to the circuit; you can practice by building a time-delay circuit.

Things You'll Need

IRF510 MOSFET
Yellow LED
1k-ohm resistor
1.0M-ohm resistor
1 microfarad electrolytic capacitor
Pushbutton switch
9V battery `
Battery holder
Solderless breadboard
Jumper wire

Instructions

- 1
  Choose one row on the breadboard that represents positive voltage, and then choose another that represents zero voltage, or ground. Add the red lead of the battery holder to the positive voltage row and the black lead to ground.
- 2
  Insert the MOSFET horizontally into the breadboard so that its three leads are in separate columns (review the datasheet if you don't how to identify them). Place a jumper wire between the column that the source is in and the ground row.
- 3
  Connect the LED to the MOSFET's drain and add the 1k resistor to the circuit. To do this, insert one end of a jumper wire to the column that the drain lead is in; attach the wire's other end to a column on the breadboard that is unoccupied. Place the LED's negative lead into this same column, but insert its positive lead into a separate location. Attach one end of the 1k resistor to this new location, and attach its other end to the positive voltage row.
- 4
  Insert the capacitor's positive lead into the gate column, and place its other end at ground. Attach the 1M resistor parallel to the MOSFET, so that one side also falls into the gate column as well, and its other side into a new column. Add one end of the pushbutton switch to the new column. Place the other side of the switch into the positive voltage row.
- 5
  Add the battery to its holder. Charge the MOSFET by pushing the button and then releasing it. The LED will light, and then turn off slowly.

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