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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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How to proportion hydraulic flow using potentiometer and MOSFET

I am working on solving a problem that we generally deal with in a mechanical fashion. We have a hydraulic system with a dumb controller and a dumb valve stack. We can change the valve stack solenoids ...
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36 views

A problem with using 2 MOSFets as switch

I have a problem with following circuit. I think that the problem is, both MosFets are 'on' at the same time. Here is the characteristics Vgs(t) of both of them. What have I done wrong? I'm expecting ...
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65 views

Freewheel diodes and shoot-through prevention required on this low-voltage H-bridge?

I have built the following h-bridge: VMOT1 is at logic level (3.3V) FWD and REV are driven by MCU (no PWM in the scope examples given) Q7/Q8 are DMP1045 Q9/Q10 are BSS138 D3/D4 are 4 x 4148 the 2 ...
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18 views

Simulating process variations

How to simulate Drain current vs Drain source voltage characteristics of a NMOS with respect to process variations in LT Spice?
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73 views

What is the maximum voltage the capacitor can be charged in this circuit?

This is a single transistor DRAM circuit. We drive the WL and BL voltage to 5 volts. What is the maximum voltage the capacitor Cs can be charged? Is the dependency of Vth on source voltage important ...
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1answer
70 views

DC motor causing project to work unexpectedly

We have developed in protoboard the following schematic for driving a DC motor with transistor for Arduino, but instead of using the PN2222 transistor, we are using a MOSFET IRF540, and instead of ...
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31 views

Mosfet based inrush current limiter review

Please find below the schematic of a mosfet based inrush current limiter. It works in simulation (Tina TI) but I would like to get your opinion. Do you think the schematic below is a good approach to ...
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58 views

High Voltage Regulator

I have built a valve/tube tester. To provide the various screen and plate voltages I'm doing this: The required voltage is selected by a rotary switch down the stack of zeners. The momentary button ...
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27 views

Choosing Q point for MOSFET amplifier

These are some lecture notes for MOSFET amplifier. Why has he chosen Q point using Vd? Shouldn't Vds = 1/2(Vdd + Vgs - Vt) ?
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Can I drive a high-side N-channel MOSFET with NPN transistor and extra battery? (H-bridge)

I read discussions about only using N-channel MOSFETS in h-bridge circuits. I often see things like optoisolators listed. Example: driving high-side N-channel MOSFETs in H-Bridge But why can't I just ...
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13 views

Low Side Mosfet protection circuit

I build a current limiting circuit, which clamps the current to lets say 4A. Id like to add a mosfet protection, which copletelly turns off the power mosfet, if Drain - Source is higher than 6V. In ...
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17 views

Difference between body, bulk and substrate?

I have a pretty fundamental question related MOSFET devices. I am confused about whether the terms body, bulk and substrate are all just names for the same thing or are there actually some differences ...
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81 views

Do mosfets without protection diode exist?

If they do exist, what is advantage of using them? How often are they used in comparison with mosfets that have integrated diode?
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19 views

Combining two schematics of 1kx3 NOR MOS PROM components into a 2kx6 PROM component

Today after class we were left with an exercise of creating schematics and combining two components we learned about today. The exercise is to combine two 1kx3 NOR MOS PROM components into a 2kx6 PROM ...
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21 views

Damaged (auto) battery charger - which component most likely? [closed]

I recently (stupidly, in the dark, late at night) mistakely connected my auto battery charger in reverse. The current flow from the alternator did some damage to the charger. Before I begin ...
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1answer
44 views

Cost vs quality and performance of H-bridge

I'm working on a project where low cost and small BOM is just as important as optimal functionality. The goal is to drive a cheap DC motor (aka 'yellow motor'), in two directions, optionally with PWM. ...
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1answer
25 views

custom solenoid trigger circuit

I have a custom made solenoid that is required to work at 60V to actuate with enough force. I have tried two circuits shown in the figure below but both don't work. In the first circuit, the voltage ...
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59 views

Turning on/off power to NeoPixel Ring with MOSFETs from ESP12-F

I am creating a pcb with ESP12-F which will contain Neopixel Ring 12. As this will run 24/7 and Neopixel even when completely off drains about 15-20mA and I will have several of those the consumption ...
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14 views

MOSFET depletion region and diffusion electrons

As Voltage from Drain-Source increases, this means the Drain voltage increases. I understand why the depletion region around the Drain increases, since it is more positive minority carriers will fill ...
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1answer
18 views

LTSpice - PMOS Gate not turning on

My question is why is the M2 PMOS FET not turning on when Vchrg_ctrl is LOW? My problem is Vload never goes high to charge the Capacitor C1. I think I am missing something very silly here. Thank you ...
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40 views

Problem using mosfet in my vape mod design

I'm trying to build a tiny 2xAAA NiMH battery vape mod. I know NiMHs are relatively more safer than Lipo or Li-ion batteries, and in my setting (coil's about 1.5-2 ohms) I could just directly connect ...
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3answers
43 views

Can MOSFET drain current be higher than rated if the drain-source voltage is below rating?

Sorry, a very noobish question here. I'm trying to understand if MOSFET ratings work on the principle that current and voltage are proportional (like Watts) or whether each rating is separate and ...
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16 views

Supply independent current reference

Given is the circuit for supply independent current biasing. What are the spice models that should be used in place of nmos and pmos so thay we get the desired output? It is required that the aspect ...
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1answer
63 views

Why voltage drop accross a load is higher in case of inverters? [closed]

I have built an inverter circuit, where the circuit works properly for light AC loads e.g. 9 watts, 230V LED bulb etc. and gives an output voltage of 200v, but if I use a 70 watts, 230V exhaust fan as ...
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15 views

Power staging design with DC plug and charger

I want to build a device that contains a Raspberry Pi and a STM32F103 based MCU. It should run either with an external 5V power supply or with a built in LiPo battery. To keep things simple, most of ...
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1answer
44 views

BJT-piloted MOSFET circuit: Feedback requested

I had the idea to make a power converter, and I would like some feedback. I can take constructive criticism. The basic idea was to make something where a microcontroller could drive a power MOSFET, ...
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100 views

How to define a microcontroller pin as open collector or open drain?

Source I have understood the fundamental theory of open collector and open drain configuration. But the problem is how to define/make a micro controller's pin as open drain? Can any pin of a micro ...
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2answers
67 views

How does a high amperage (100 Amps or more) MOSFET handle the current flow without overheating?

High amperage MOSFETs like the 511-STP200N3LL say they can handle 120 Amps of current. Is this possible? If yes, then what prevents the small wires coming out of the device from melting or getting ...
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23 views

Dual-gate mosfet gate resistance at DC

I'm investigating a bf1105 dual-gate mosfet for use in an rf mixer circuit. I've never used a dg mosfet before so I decided to do a DC sweep of the gates to determine an appropriate bias point. I ...
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2answers
30 views

Vds vs. Rds(on) on 19N10L mosfet

I measure in common source connected mosfet (19N10L) Vds about 2.4V in on state. The current is 2A. In datasheet is defined Rds 0.1ohm. Why is Vds in this mosfet so high (2.4V)? Shouldnt be Vds = 0.1 ...
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3answers
39 views

Mosfets differing in aspect ratio [closed]

Which are the mosfets exactly similar to the mosfet 2N7000 but differ in its  W/L ratio so that it can be used in applications where you need differing aspect ratios ?
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Mosfet parameters from Datasheet

Is it possible to find out the W/L ratio and process transconductance parameters of a mosfet from it's datasheet when it is not directly given ? If yes, how ?
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67 views

How does this circuit with inverters work?

What this does this circuit do? I suspect it is an amplifier, but don't know how it amplifies. For example Inv 5 and Inv 6 are connected in parallel with reverse sides but there is a wire between ...
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34 views

CMOS Inverter circuit

I want to design CMOS Inverter which gives: 0 volt input --> 5 V output Any positive input voltage above threshold voltage --> 0 V output. On simulating, it is giving me alternatively +2.5v and -2....
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66 views

MOSFET as Power Switch Issues

I am trying to use a N-channel MOSFET to toggle battery power going to a 5V voltage booster using the circuit shown in the attached image. Battery voltage is 3.7V and the gate voltage is 3.3V. High ...
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28 views

Switching P channel mosfet transistor or an n channel mosfet

I want to control the power being fed to my raspberry using my microcontroller and a mosfet. I want to drive this using a p channel mosfet and I'm not too sure whether I should choose using an NPN ...
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30 views

How to calculate inductance (ferrite core) in a induction heater [duplicate]

this is my third tag and I´m going to accurate my question, I have builded four induction heater and only one works, I´m sure that´s because of the inductor L1, I do not know how to obtain te correct ...
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3answers
91 views

E-fuse using Mosfet

I have not succeeded to make an e-fuse according to this schematic. Basically its a simple current limiter to 14A , where the mosfet G to S structure breaks the current flow. Can someone check, whats ...
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1answer
87 views

Driving MOSFET with 5V PWM for 12V fan speed control

I came up with this circuit to control a 12V 6A fan's speed, with a 5V PWM from another circuit. I'm not sure if it's going to work (I'm not very experienced nor knowledgeable in electronics) and I ...
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2answers
88 views

Universal Analog Input [closed]

I am implementing this circuit but want to make it automated to avoid the use of jumper headers. I have replaced all the headers with P-FETs. Is this the best solution?
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1answer
390 views

Why does turning a MOSFET ON too fast cause ringing?

Going though app notes, I can understand that turning it off (i.e. when drain-source voltage is increasing) can cause ringing due to parasitic NPN and also drain-gate capacitor which can charge the ...
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1answer
47 views

What methods exist to introduce dead-time in a MOSFET H-bridge? [closed]

What methods exist to introduce dead-time in a MOSFET H-bridge? (to prevent shoot-through) (other than software methods, or using MOSFET driver ICs with internal dead-time generators)
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1answer
1k views

Is turning off MOSFET too fast, bad?

As far as i understand turning off a MOSFET too fast, is bad, as high drain-source dv/dt can cause ringing through: a) biasing Parasitic NPN and: b) charging the GS capacitor through DG capacitor, and ...
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26 views

Mosfet Vgs-Qg graph

What is the reason behind the horizontal region in the center? why gate-source voltage doesn't increase in that region, even though we are adding charges to it?
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3answers
69 views

How can you conduct a simple test for a MOSFET?

Is there a simple way of conducting a test on a MOSFET? For example, testing if a transistor is in good condition or not by using a multimeter. Can the same test work for a MOSFET?
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21 views

Fiterless Class D amplifier: the PWM and Switching stage

What is the minimum voltage and current to drive a MOSFET switching stage for a filterless class D amplifier having 86% efficiency? What ae the calculations needed to find this out?
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1answer
46 views

What's the purpose of diode between high side and low side supply voltage of IR2110?

What's the purpose of the diode between VCC and VB?
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39 views

Can i use IR2110 for two independent MOSFETs?

Can i use IR2110, and feed it with two independent PWM signals, to drive two independent MOSFETs, each controlling a separate motor? (or high side and low side inputs/outputs of this chip gonna affect ...
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1answer
50 views

Driving MOSFET from MCU with BJT

1- What is the purpose of D1 in this circuit? 2- Can i connect the PWM output of MCU to Vi through a diode, to protect the MCU from 12V supply of the drive circuit? (e.g. if Vi got accidentally ...
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32 views

Understanding MOSFETs Driven by Analog vs. Digital Signal

I plan to run a circuit with two 18650s in parallel to get 7Ah of capacity and a 3.3V rail (for running the ESP32 MCU). I'll use an LDO to get my 3.3V until the battery voltage drops to 3.3V. At that ...