MOSFET Properties - Turning On/Off with 2n7000

In summary, the speaker has been experimenting with a 2n7000 MOSFET and has found that to turn it off, they either have to wait a few seconds after putting the gate at 0v, or apply negative voltage to the gate. They are wondering if this is normal for MOSFETs or FETs in general, or if it is a sign of a faulty MOSFET. They also mention that the MOSFET should turn off at 0v at the gate. Another person suggests that the speaker may have a floating gate due to incorrect wiring or handling the MOSFET improperly.
  • #1
Kerso1991
7
0
Hiya, I've been mucking around with a 2n7000 MOSFET and I can successfully turn it on and off, but to turn it off I either have to put the gate at 0v and wait a few seconds and it turns off itself or apply negative voltage to the gate and it'll stay off when I return it to 0v. Is this normal for MOSFETs or for even just FETs? Or is this just a dodgy MOSFET? Because as far as I know the MOSFET should turn off at 0v at the gate
Any help would be great
 
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  • #2
How are you changing the voltage on the gate? Does the 0V reference point (GND) of the controlling circuit have a DC connection to the source of the FET? The switching of the FET requires charging and discharging of some capacitance inside the device.

I had a similar experience debugging a circuit I put together. I forgot to wire all of my grounds together. As I recall, the FET was a 2N7000.

BoB
 
  • #3
Kerso1991 said:
Hiya, I've been mucking around with a 2n7000 MOSFET and I can successfully turn it on and off, but to turn it off I either have to put the gate at 0v and wait a few seconds and it turns off itself or apply negative voltage to the gate and it'll stay off when I return it to 0v. Is this normal for MOSFETs or for even just FETs? Or is this just a dodgy MOSFET? Because as far as I know the MOSFET should turn off at 0v at the gate
Any help would be great

You have connected the source to 0V, a large resistor between the gate and the source and a 1k resistor from the drain to +5V? Your problems seem to me as if the gate is floating...

Check the pinout and your wiring again. Possible problem: Because of the extremely high input impedance at the gate, it is very easy to destroy a MOSFET just by handling it.
 

Related to MOSFET Properties - Turning On/Off with 2n7000

1. What is a MOSFET and how does it work?

A MOSFET (metal-oxide-semiconductor field-effect transistor) is a type of transistor that is commonly used in electronic devices. It works by using an electric field to control the flow of current between the source and drain terminals, allowing it to act as a switch or amplifier.

2. What are the properties of a MOSFET?

The properties of a MOSFET include its ability to handle high currents, low power consumption, and fast switching speeds. It also has a high input impedance and low output impedance, making it suitable for use in a variety of applications.

3. How does a 2n7000 MOSFET turn on and off?

A 2n7000 MOSFET turns on and off by applying a positive voltage to the gate terminal. When the voltage is applied, the electric field created by the gate attracts electrons towards the channel, allowing current to flow between the source and drain terminals. When the voltage is removed, the electric field dissipates and the MOSFET turns off.

4. What factors affect the turning on/off of a MOSFET?

The turning on/off of a MOSFET can be affected by factors such as the gate voltage, gate-source capacitance, and channel length. Additionally, the materials used in the MOSFET and the temperature can also impact its performance.

5. What are the advantages of using a MOSFET over other transistors?

MOSFETs have several advantages over other transistors, including their high switching speeds, low power consumption, and ability to handle high currents. They also have a smaller size and can be easily integrated into electronic circuits. Furthermore, MOSFETs have a high input impedance, which allows for easier control and manipulation of current flow.

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