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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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33 views

MOSFET or Transistor FM Receiver Circuit [on hold]

I am trying to build a very crude fm receiver with some simple parts. I have searched the entire internet and have found nothing fitting my query. I have 2N2222 and 2N3904/2N3906 and N-Channel MOSFETs....
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What MOSFET should I use? The number and some advice [on hold]

I have a DC motor 24V 150W and I need to control the speed of the motor so what is a good MOSFET for my application? The control signal is done by sending PWM from an Arduino Uno.
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How do I solve the input resistance of this BJT and MOSFET in series?

This is a sedra-smith microelectronics excercise question for which I can not find the answer and I hoped for perhaps a solution here?
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28 views

How to get the gain for this MOSFET amplifier?

This is a common drain MOSFET amplifier: simulate this circuit – Schematic created using CircuitLab This is its small signal model at low frequency: simulate this circuit I am at a loss as ...
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41 views

What does worst-case gate capacitance mean in a MOS transistor?

I have searched the statement; MOS worst-case gate capacitance in various forms but no avail. Keep in mind I'm a student. The course I am taking has no reference material. With note slides with ...
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47 views

MOSFET, the effect of the gate voltage

Here the gate voltage is 5V and lots of the 12V input voltage stays across drain and source. Here the gate voltage is 12V and still some voltage stays across drain and source but this time smaller. ...
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78 views

Driving two MOSFETs with one AND Gate?

I am designing a circuit to drive the brakes on a DC motor. The brakes are a 19.9Ω coil that is disabled when energized (think wheelchair motor style brakes). The brakes work on 24VDC. I have found ...
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99 views

Is there Mosfets for wires? [on hold]

Mosfets are pretty cool but they are either designed for circuit boards or for breadboard's. Is there a version of a mosfet that can be used for slightly thicker wires than what would be usually ...
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104 views

What is wrong with this circuit simulated in Proteus?

When simulating this circuit in Proteus, I expect the LED to light up when the switch is closed, but it does not light up. What am I doing wrong?
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38 views

Trouble controlling LED strips with n-mosfets on 2 power supplies

I have 2 equal power supplies and I try to control LED strips using arduino and n-channel mosfets. I've split the strips between the supplies, strip A + arduino is on one power supply, strip B is on ...
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45 views

Send an AC signal from a DC device

I was able to read a 18VAC signal from the old-school door bell with a voltage divider to my 3.3VDC ESP controller. Nice. Now, I wish to send a 18VAC signal (for 3 seconds) to open the door with that ...
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Spark plug trigger with time delay

I'm currently working on a personal project where, a part of it, is having a spark plug discharge with a time delay after a signal is sent. Below is the schematic I've come up with so far but I'm not ...
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How does this simple tesla coil circuit work? [on hold]

I'm wondering how this circuit works. I built it and it works but I'm not sure how it works. I would love a detailed explanation about every component function in the circuit and how it works.
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78 views

Series diode instead of a flyback one

My question is can I use a diode in series with a MOSFET, instead of pusing it as a flyback diode. simulate this circuit – Schematic created using CircuitLab
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47 views

FET-based H-Bridge for bi-color LED

I've got a bi-color LED in a push-button that is red when powered in one direction and green in the other direction. I would like to control it from a Raspberry Pi GPIO pin, e.g. High=Red, Low=Green. ...
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40 views

Parking Light And Signal light with same LED using MOSFETS

I have a project where I have an existing 12v parking light and I want to also have the turn signal use the same light. I've constructed a circuit using 2x NMOS and 1x PMOS. I think it will work and ...
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52 views

IR Light Detector as MOSFET Gate

I would like to use an IR transmitter/receiver pair to detect when an object obstructs (or does not obstruct) the path between the the transmitter and receiver and illuminate an LED when the path is ...
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46 views

high current passing through mosfet is damaging the nrf52

simulate this circuit – Schematic created using CircuitLab recently trying to make a led strip that can be controlled over bluetooth. I need high currents up to 10A. for the test purposes I ...
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37 views

MOSFET simulation model

I am trying to model a synchronous buck converter, for which I need to choose mosfet models for simulations. I am seeing that it has various parameters out of which length and width is affecting the ...
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69 views

Where is the voltage drop? / How can I test circuit this without using an actual battery?

I've put together the following circuit, it's just a rechargable LED torch, just to try load sharing: simulate this circuit – Schematic created using CircuitLab BAT1 is a LiPo battery, 5.2 V ...
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SiC MOSFET SPICE model not behaving properly

I have been trying to simulate a fully controlled full bridge using SiC MOSFETs and so far haven't gettng at least expected results. So I tried to check what is happening using a single MOSFET and a ...
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1answer
38 views

Requirements for low voltage, low current MOSFET used in current source

I'm trying to determine the minimum requirements for a MOSFET that will be used in a op-amp based current source. I've hit Google and this site and looked at multiple pages, but almost always, they ...
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N-Channel Mosfet or NPN transistor for Low Power PWM Application

simulate this circuit – Schematic created using CircuitLab LED: 2.05V @ 350mA 5-6 Ohm Resistor for current regulation Hi, currently designing a circuit that controls a LED using a PWM logic ...
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Switching 5v with Arduino

I need to control the state of an El Wire light tube with a USB power supply connector with an Arduino Nano or Uno. I want to avoid relays because of the loud click sound. As I'm pretty bad at reading ...
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130 views

IRF7821: is one of them fake?

Left looks like genuine (logo), right looks like fake. Is it, really? Edit: this part is expected to be IRF7821.
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113 views

MOSFET as heating element for a RaspberryPi

I developed a PID autotuning algorithm that I want to test outside of a simulation environment. For this purpose, I got temperature sensors to send data to a RaspberryPi. Now I need something to ...
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22 views

Current flow in trailing edge dimmer

I was trying to learn something about dimmers for light bulbs. After some reading, I found that most trailing edge dimmers contain some variant of this: Found for example in this diy-project or this ...
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76 views

MOSFET Triggers with Electrostatic Energy

In the attached circuit with a 5V relay and a 30V load across it, I've noticed the FQP30N06L MOSFET triggers with even electrostatic energy (touching the gate). The difference between the circuit ...
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Gate Current Calculation and Practical Mosfet Selection

Vnoo3 is the drive voltage, and Ig is the gate current. What I am wondering is: 1) How to calculate the peak Ig on the rising edge of the pulsed gate voltage? For instance, using the spice image ...
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31 views

In the pao sah model of MOSFET!

Hi I'm studying semiconductor and i got stuck in the concept of MOSFET. In the case of pao-sah's model, we set our electron concentration and hole concentration as following pictures that I attached. ...
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33 views

NMOS Switch, Drain Source Location

I just have a bit of confusion about which way to orient MOSFETs in IC switches for sample and hold circuits Which one is it? Or does it not matter?, since the Source and Drain potentials will be ...
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20 views

Power Gain in a Small Signal Mosfet Circuit

let's consider this circuit, which is the equivalent of a small signal Mosfet amplifier. where RG is a gate series resistance which takes into account of the oxide leakage, and CGS and CGD are the ...
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48 views

Effect of drain inductance on MOSFET turn off

I have made a simple circuit in LTSpice to test MOSFET turn-off time. Inductance is changed from 1.5nH to 1.5mH in a few steps. The next picture shows gate-to-source voltage and drain-to-source ...
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43 views

P channel mosfet as a switch on logic level

I'm quite confused about the p channel mosfet as a switch. I saw designs with zener diodes, other mosfets or BJTs but these seem overcomplicated. I have many P channel mosfets from broken chargers (...
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163 views

Resistance of mosfet's internal diode

I am an IoT solutions developer and not an engineer, so please excuse my vocabulary if not upto the mark. I have used Mosfets such as FDD6637 and IRF9310 in my circuits for power switching and they ...
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41 views

Isolating grounded resistance? Glow plug thru MOSFET

Have an Arduino triggering an LED array AND a MOSFET that burns a glow plug for 1 second, from the same power supply (3.7V 720mAh Lipo). The issue is that when the mosfet is triggered, it seems to ...
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84 views

Reduce minimum operating voltage of an H-bridge

I have purchased the following H-bridge and I'm controlling it with a microcontroller: https://www.amazon.com/H-Bridge-Brakes-Forward-Reverse-Full-Duty/dp/B07GFFVZKS My problem is that the MOSFETs ...
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136 views

Is it possible to use a Mosfet in switching mode as an electronic load?

I'm trying to use a mosfet as an electronic load to measure the IV curve of a solar cell, but if I use it in linear region it dissipates too much power. I was thinking that I could use it in switching ...
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Short Channel MOSFET model

I was reading on a book (Thomas Lee, The Design of CMOS Radio Frequency Integrated Circuits) that in a short channel model, since the phenomenon of drift speed saturation is very relevant, it is a ...
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77 views

How can this PWM converter circuit be improved?

This circuit is intended to use a 1-10Hz PWM signal as input and produce a 1-10kHz 10A PWM output. It will be used for controlling the speed of a water pump: GP1352 The PCB will be ordered with (only) ...
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1answer
47 views

Circuit to identify phase difference between capacitor voltages of two different RLC circuits without loading it

I am looking for a circuit that can translate phase difference of two sinusoidal signals (operating at ~1MHz) to analog voltage swing of 0 - 5V. The signal A & B comes from the capacitors of two ...
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41 views

Why does an ISFET need a reference electrode?

I'm trying to understand why an ISFET needs a reference electrode. I have looked up several answers online but still dont understand. I have drawn out the doping, a MOSFET and the ISFET: In my mind, ...
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69 views

Can I power a MOSFET from my uC in this way?

The uC is a PIC10F220, which if I read the datasheet correctly can supply 25mA absolute maximum on its pins. The MOSFET that drives the load is actually 4 pcs NCE0140KA in parallell, but drawn as one ...
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41 views

Need help for using N-Mosfets to switch on either one battery or the other

I'd like to add a second battery (36V Li-ion) to an ebike to increase its range. My goal is to use one battery at a time, not using both in parallel with e.g. ideal diodes or something. I'd like to ...
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56 views

MOSFET as a Capacitor in IC

I was reading in a book that it is often possible to realize a certain capacitance in Integrated Circuits by exploiting the Gate Capacitance of a MOSFET. I read that the main disadvantage of this ...
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1answer
52 views

What is the use of two n mosfets with their sources tied together?

The circuit I'm looking at recommends two n-channel mosfets in series with their sources tied together between it's output and the power input. pin description: High voltage open-drain gate driver,...
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80 views

driving mosfet gate with an npn bjt

simulate this circuit – Schematic created using CircuitLab Today I saw an led dimmer product. the driving circuit was like in the schematic. it was a cheap one but the circuit looks inefficient ...
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26 views

Finding node voltages in a MOSFET circuit

simulate this circuit – Schematic created using CircuitLab Considering Vdd=5v I want to calculate the node voltages at P,Q and R.
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79 views

Equivalent resistance in this mosfet circuit

simulate this circuit – Schematic created using CircuitLab I have 3 NMOS are connected as shown above. I need to calculate equivalent resistance as seen by the capacitor so that I am able to ...
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Comparison of the SOAs of two MOSFETs

Below the SOA for the IXFP6N120P: And the SOA for the IRFBG30: The first one shows a DC line beyond 100 ms, but the second one does not. Does this mean the second one is unreliable beyond 10 ms, or ...