MOSFET Properties - Turning On/Off with 2n7000

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SUMMARY

The discussion centers on the operational characteristics of the 2N7000 MOSFET, specifically regarding its gate voltage behavior during switching. Users report that the MOSFET requires either a prolonged application of 0V at the gate or a negative voltage to turn off effectively, which raises questions about normal functionality. It is confirmed that proper grounding and wiring are critical, as floating gates can lead to erratic behavior. Additionally, the high input impedance of the gate necessitates careful handling to avoid damage.

PREREQUISITES
  • Understanding of MOSFET operation, specifically the 2N7000 model
  • Basic knowledge of electronic circuit design and grounding principles
  • Familiarity with gate voltage control and its impact on MOSFET switching
  • Experience with handling sensitive electronic components to prevent damage
NEXT STEPS
  • Research proper grounding techniques in MOSFET circuits
  • Learn about the effects of gate capacitance in MOSFET switching
  • Explore troubleshooting methods for MOSFET circuits, focusing on the 2N7000
  • Investigate alternative MOSFETs and their gate voltage requirements
USEFUL FOR

Electronics hobbyists, circuit designers, and engineers working with MOSFETs, particularly those utilizing the 2N7000 model in their projects.

Kerso1991
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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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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
 
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.
 

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