Questions tagged [mosfet]

An transconductance (using voltage to control current) electronic component used for switching and amplification. Acronym for Metal-Oxide-Semiconductor Field-Effect Transistor. (from http://en.wikipedia.org/wiki/Transistor)

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26 views

Designing simple class a amplifier using mosfet

I'm trying to build a simple class a amplifier using a mosfet. I have read few articles about how to do it, but I'm just confused now. I'm not sure how to select resistor values. The articles I've ...
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How to drive the gate of a MOSFET with a PWM like signal

I'M trying to use MOSFET as a driver for my 10W LED with 12V supply. This LED will be used as a transmitter with signal coming from Arduino nano. I'm using IRFZ44N MOSFET with a Vgs(min)=2V and Vgs(...
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Why does my input current inverter is high?

I have a problem with input current in my inverter is high. My inverter will use for solar panel and using boost converter to convert dc voltage 12-18 Volt to 24 volt. I'm using P channel mosfet ...
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83 views

What is meant by the MOSFET is pinched-off?

What is meant by the MOSFET is pinched-off? It is same as in the JFET case where the depletion region becomes too large until the electron cannot flow through the transistor?
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What can I use to switch a 500mA 12v inductive load from 3.3v Output

I have a ESP8266 that needs to switch a water valve that draws 500mA on 12V. What can I use to switch that load? Right now I think I will use a logic level Mosfet but I am a bit lost with choosing the ...
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LTC7001 Mosfet Driver is not working because of DPDT Relay

I am using a mosfet driver(LTC7001) to drive a mosfet. The mosfet is conducting 28 V continously which means its driver is always open. In a step I must reverse polarity of load by using a DPDT relay....
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42 views

Mosfet PWM vs Pot

I have a dumb question concerning MOSFETs. When considering voltage to the Gate, is there any benefit to using a PWM signal vs a variable voltage from a pot beside power savings? If I am trying to ...
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39 views

Using a DS3231 RTC alarm + MOSFETS to turn on a MCU

I'm using a DS3231 in conjunction with two IRLZ44N MOSFETs to switch power to a MCU when the alarm on the DS3231 triggers. The alarm on the DS3231 pulls the SQW/INT pin to ground and turns on the MCU ...
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28 views

Do PMOS Reverse Input protect on ORed power rail

As the title says, I have a power mux IC and two power inputs. I need them to be protected from reverse voltage input. The power mux i have already comes with a reverse voltage input protection but i ...
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Selection of transistor

Suggest a transistor as common base mode and 220v input (emitter) 4v base To use it as a switch As it is used in water pump which is used directly by plugging in board that is at 220v alternating ...
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23 views

How do I calculate Vsig max here?

Is "limitation on the peak sinusoidal input" Vsig max? and if it is, what difference does it being "max" make and how do I get it?
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Advice for High Side Switch (High Current, Low Voltage)

I'm building a small LED driver microcontroller board and I'm looking for any advice y'all have on switching the power to it up to 9A (would take 3A, if necessary) at 3V - 5V, in a small package. I've ...
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Drive series of 1W led with mosfet

I've to switch on for a short time a series of 6 or 7 leds with a 24Vdc. Follow some details... power supply: 24VDC led: 1W CREE XRE Q5 link Power: 1W Voltage: 3-3.7V Current: 300-500mA this small ...
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26 views

Common Source Amplifier Pmos?

What is known as a common source amplifier is often built with an NMOS, where the bottom channel (source) is connected to ground. What if you switch out the NMOS with a PMOS, and the bottom channel is ...
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Mosfet load control - different design compared

i've seen in a forum this design (Circuit 1) to drive a load using mosfet, i'm wondering in which differs from the "well-known" MCU mosfet driven loads like the second one in the image below (Circuit ...
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31 views

Single input controlled full H bridge for piezo buzzer

I would like to incorporate a buzzer in a PCB design. It would not be a coil buzzer, but more a piezo buzzer, and its operation is to be controlled with a micro-controller powered by the same voltage ...
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67 views

How to use MOSFET as an active load resistor?

In the Albert Malvino's "Electronic Principle" book, an active load switch is done by using a MOSFET as an active resistor by connecting the gate to drain(two-terminal device)(figure a) Two terminal ...
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About MOSFET ı couldn't solve help please

This is my homework but ı couldnt solve it please help me
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How can I gate the output of this phase detector?

I want to make a PLL which will lock to the subcarrier of a composite video signal during colourburst. The colourburst is present for about 2.25uS of each scanline which is 64uS long. So during that 2....
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lt spice simulations including mosfet

to lt spice users, how do you include a MOSFET into your ltspice circuit? if it helps the mosfet I'm trying to include is IRLZ44N
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Am I using the right resistors with these MOSFETs for an ESP8266 controlled LED strip?

this is my first question here. I hope I don't mess it up. I made a WiFi controlled LED strip about a year ago. The LED strip is one of the "dumb" (no individual pixel control) 12V ones and I used a ...
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35 views

MOS current mirror region of operation

The mosfet M1 is clearly in saturation as gate and drain terminals are shorted. Why we take M2 also in saturation? I know Vgs1 = Vgs2 and they are identical MOS but i cant justify why M2 should be in ...
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MOSFET based audio switch generates thumping sound

I need to switch on and off an audio signal without clicking or thumping. I have tried the below circuit that I designed and simulated in LTspice, but it generates a thumping sound when I wire it up ...
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Confusion in max drain current and on-state drain current of 2N7000 E-MOSFET

Below is the datasheet of 2n7000 series of N-channel E-MOSFET. As you can see on the marked box: Max-Drain Current(continuous) :200mA On-state Drain Current: 600mA (typical) Why is the max rating ...
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Calculating MOSFET gate current with \$Q_\text{total} = I_\text{gate} \cdot t\$

Hi I am using the MOSFET IRFP4368. I want to use the equation $$ Q_\text{total} = I_\text{gate} \cdot t $$ to calculate the required gate current of my MOSFET driver. I have my total \$Q_\text{total}...
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58 views

How bootstrap capacitor voltage is added to source voltage?

Circuit diagram below is a high side n-channel mosfet with bootstrap(while C1 is discharging) It says that after charging of bootstrap capacitor: The upper optocoupler opt1 gets ON for 1s and ...
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Solenoid flyback considerations in this pFET/nFET inversion circuit

I am trying to combine FETs, where logic permits, to reduce the size of a pcb. Is it poor practice to have the pFET's gate and nFET's drain shared by an inductive load that will usually be grounded ...
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64 views

Common drain small signal analysis and unresolved question for fet

question: There is an amplifier circuit obtained between JFET and MOSFET. For the FET used in the circuit, IDSS = 8 mA, VGSoff = -3V and working point current is 1.42 mA. Use MOSFET parameters as ...
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194 views

Is the current, Ids, through a MOSFET truly 0 when in the cutoff region?

I was testing a circuit using this circuit simulator and found that the nMOS transistor had a current of a few nanoamps running through it when it was in the "off" state. This was unexpected because I ...
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50 views

LDO datasheet parameter extraction

In similarity to previous question Ron setting of LDO. Unfortunately I assumed gain of the error amplifier and trial and error method I matched with dropout curve in the datasheet. Query: How to ...
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55 views

Why is there a positive temperature coefficient in a MOSFET?

When the temperature in a MOSFET increases: resistance increases and mobility decreases thus avoiding thermal runaway compared to BJT. But what is the reason for increasing resistance and decreasing ...
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Can anyone help to identify this blown MOSFET? Top markings seem to include F50, “ON” in a circle, 3N and “RE4T” in a circle

I am trying to repair a PCB out of the welder. One of the problems I have found is a blown MOSFET. I have tried searching for a replacement with no luck, as I don't have a complete code. I have posted ...
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Modify LED circuit with a MOSFET

I have this existing LED circuit with 2 LED strips with built in resisitors and 1 switch. Normally 1 LED strip is always on and when the switch is closed the other LED strip also turns on. Power ...
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What is the use of epitaxial layer in vertical MOS?

In a vertical MOS(figure below), what is the use of the epitaxial layer? I understand that this epitaxial layer is a lightly doped n-type layer. Being lightly doped, it will have a high resistance ...
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40 views

Why CMOS turns on when input voltage is zero?

When the input voltage is high, Q1 is off and Q2 is on. In this case, the shorted Q2 pulls the output voltage down to ground. On the other hand, when the input voltage is low, Q1 is on and Q2 is off. ...
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Issue with low voltage for mosfet gate

I am a beginner when it comes to electronics so I would appreciate your help with a simple project I am working on and have been struggling with for several days. The idea is that I have a PIR Sensor ...
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36 views

AC MOSFET amplifier design problem

The source follower amplifier circuit shown in following figure transistor parameters are Vth = 1.2 V, kn = 4 mA/V2, λ = 0.01 V-1. Assume that gm = 11.5 mA/V. Vdd = 12. Design the values of R1, R2, ...
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ultrasonic mist maker

I am working on an ultrasonic mist maker for my school project but I can't seem to make the piezoelectric disc work and the MOSFET keeps burning up. Can s.eone help me figure out what's wrong? ...
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How can I find the drain transfer function of a MOSFET on LTSpice?

I am trying to get the drain transfer function of a MOSFET by setting the drain to source voltage as the input and the gate to source voltage as the output. I created the following circuit in LTSpice: ...
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N channel not created help [closed]

I am connecting this power mosfate to gate voltage of 1.7V its electric characteristics say 2.5 max threshold voltage and the source substrate pin to ground and the Mos capacitor made of the substrate-...
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circuit design to output high voltage MHz high frequency [duplicate]

I'm trying to design a circuit that outputs 4.5 KV alternating between two nodes at about 4Mhz. What would be the most efficient way of doing this? I thought of using 4 4.5 KV rated transistors as in ...
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36 views

Switch Power Supply at 24V using MOSFETs

As title, here's a schematics: simulate this circuit – Schematic created using CircuitLab Is this a correct way to create a power switch or can this schematic be improved? Board will sink at ...
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53 views

How to PWM a load regardless of the direction of current?

I'm helping a student at our art academy with an interesting project. She is building an array of peltier elements (let's say 25 to start with). She wants to control them individually using PWM and be ...
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59 views

How is a PMOS transistor used as a switch?

I am trying to understand switching behaviour of PMOS transistor and how exactly it passes a bad 0 value. I'm getting confused with the notation. More specifically, when the PMOS is on and $$V_(in)=...
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70 views

Why is the input to output delay time for transistors not provided in the datasheet?

I am using this BC807-40 transistor. My maximum collector current through the transistor is 200mA. I want to calculate the delay time between the transistor input Vbe and output Ic. Is there a way ...
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How to safely expose one wire of an AC mains circuit?

I need to use a rail to connect one moving piece where a switch is, to a fixed piece where a power tool is. The rail is exposed, so I need this connection to be safe, like 12V or below. I'm guessing I ...
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105 views

High-side switch to disconnect battery

I have a 28V power source and a 24V power source on my device. The 28V source is permanent (internal battery) and the 24V can be disconnected. When 24V is connected, the 28V battery needs to be ...
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Unpredicted behavior in an energy harvester circuit using max666

I conducted the simulation of a circuit used for energy harvesting. Its functioning is explained in detail in How the voltage stable mechanism work in Bridge rectifier?. But it was observed in the ...
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29 views

FQPF5N60C MOSFET turns on but limited current

I am a software engineer by trade and an electronic hobbyist, so please be gentle :) I am using a FQPF5N60C N-Channel MOSFET to switch on a 12v motor using a Raspberry Pi. The spec shows VGSth at 2 -...
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What's the purpose of components in these mosfet driver

I see these double ended transformer drivers on many places, I know the working principles of these gate drive transformers but still don't have an idea about external components that I've marked with ...

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