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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Building a +/- 150V DC power supply

I'm trying to build a +/- 150V battery powered DC power supply variable power supply. I have two of these 150V nixie power supplies: http://desmith.net/NMdS/Electronics/NixiePSU.html And was ...
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41 views

MOSFET Behavior During Pulsed Operation

I am trying to use back-to-back MOSFETs/IGBTs to isolate my pulsed supply from my load. In theory, I will switch on the MOSFETs, and the pulsed supply will be attached directly to the load (but not on ...
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2answers
86 views

Calculate mosfet gate resistor?

I got this schematic : In the image you see; I'm driving two infrared leds at 40 Ma each one with a FDN327N Mosfet. Attached at D8 there is one of Teensy 3.1 digital output that has HIGH voltage ...
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57 views

High-side switch for 5V load

I need to control a 5V 60mA load from an Arduino pin, but as the load has an output (tacho) that I will be reading from the Arduino, it seems I need to connect it as a high-side switch. What would be ...
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51 views

High power LED strip dimmed by MOSFET and microcontroller

I'm planning on creating a system to control a high power LED strip from a microcontroller (probably and Electric Imp) using an N-Channel MOSFET, but I've always had a hard time with MOSFETs in the ...
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61 views

Very intermittent power MOSFET failure

I am working on a very spotty motor failure (I am not the designer). We have a wound armature which is switched by power MOSFETs. These are driven by a FET totem pole type FET driver. When the ...
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1answer
45 views

Maximum Power Point Tracking Duty Cycle for a Buck Regulator

I'm currently building a 10W high voltage (~50V-100V) Maximum Power Point Tracking (MPPT) buck regulator on the side for educational purposes. For the time being, the output is tied to a load. ...
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40 views

MOSFET Cell Balancing Circuit

I'm designing a simple cell balancing for charging LiPoFe4 cells in series. In order to prevent overcharging, when on of the cells reach the maximum charing voltage, the microcontroller will enable ...
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56 views

No output at H bridge during quick power drop

I used a H bridge with PMW control to drive DC motor in two directions. I observed a strange phenomenon that during quick voltage drop, the PWM output at M2 is cutoff, although the T4 gate PWM input ...
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53 views

Mosfet life expectancy?

How to determine the life expectancy for the given mosfet? Mosfet : IRFP460 Mosfet Datasheet http://www.vishay.com/docs/91237/91237.pdf Actual Voltage,Current and other specification. Vds = 180VDc ...
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43 views

How to Calculate Mosfet Voltages

For a N-channel Mosfet does Vds = Vdb + Vbs? Is this only true for simple models or always? Where d is drain, s is source and b is base.
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39 views

Odd MOSFET behaviour (in Multisim)

I have this circuit that's behaving in a strange manner. I am getting a surprisingly low current value flowing through the inductor when the path includes the N-channel MOSFET. Please could someone ...
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109 views

MOSFET ringing drain

Background: Using 33kHz PWM through an RF isolator [Si8710AC], to drive a power MOSFET [AUIRFZ44N], to control a high-power LED (8-10 watts). Isolator output is open-collector pulled up to +12V, and ...
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53 views

Commanding numerous motors with one H-Bridge

Is it possible to command more than one motor with an H-bridge like this: Would this work in real life if I replace switches with transistors and command them?
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1answer
78 views

Power Mosfet design issue

My schematic The components BSN20 is a N-channel enhancement mode field-effect transistor (datasheet) IRF7416 is a HEXFET power MOSFET (datasheet) This is a part of a project in which the line ...
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53 views

How does the drain current flow in a MOSFET when the channel is pinched off?

Here is what I have understood. Please correct me if I'm wrong. The depth of induced channel depends on the voltage V. Since the voltage across the gate and the path along the channel decreases from ...
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1answer
42 views

How to observe transfer characteristics of MOSFET?

I have built a simple Mosfet circuit now I want to check the Vds vs Id characteristics. But the problem is when the Vcc(Supply) and Vgs(Gate to Source) (according to the following characteristics) ...
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1answer
80 views

High side P channel MOSFET power switch - gate question, and suggestions for my circuit?

My circuit is for switching a 12V battery to a load (LED lights, designed for automotive use), during my testing with prototypes, the lights consumed about 400mA, meaning they were ~5W LED products. ...
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45 views

MOSFET current mirror: Saturation mode?

I have some trouble understanding why M1 is in saturation/active mode. According to Wikipedia a MOSFET is in saturation mode if \$V_{GS} > V_{th}\$ and \$V_{DS} \ge (V_{GS} – V_{th})\$. However ...
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67 views

OP amp voltage comparator for an FET

I have a project requiring a switch (I supply 4.8V, the switch stays off. I supply 5V, it turns on.) After some testing and asking several questions, I realized that the MOSFET I was using would not ...
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50 views

Adding hysteresis to MOSFET used as a switch

I have a low-voltage detection circuit which I use to trigger one of two LEDs (green, and red) that is powered off of a +9V battery cell. As the battery discharges, its output voltage decreases, until ...
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1answer
82 views

Mosfet Snubber with Inductive Load

I am designing switch circuit that switches on and off a relay that switches on and off a 115AC light.So the switching speed is not a concern as it is a once in a while on or off. The relay for the ...
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1answer
103 views

Brushed DC motor control MOSFET selection

I want to control a brushed DC motor of the below specification: Motor: Permanent magnet DC brushed motor Voltage: 180V Current: 5 Amps RPM: 1500 The control method is PWM switching through a ...
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68 views

MOSFET based H-Bridge Circuit

Okay really need help on constructing a MOSFET based H-bridge circuit with a switch. I've got two p type and two n type mosfets. I understand you have to apply voltage to the gates to turn the ...
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59 views

Gate Source Voltage Drop Approximation

When dealing with BJTs in an approximate large signal analysis, Vbe is often chosen to be 0.7 Volts (Given the component is operating in active mode). My question is: Is it possible to do the same for ...
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77 views

Replace mechanical switch with transistor? MOSFET? Relay?

If I have a switch in some consumer electronics that I take apart, and want to replace a mechanical switch with a digitally controlled one, which component should I use? The only problem I see with ...
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84 views

MOSFET threshold voltage and body effect

I'm trying to simulate a common drain amplifier on LTSpice which can be used to shift the input voltage either up or down by the threshold voltage (\$V_{IN}+V_{TH}\$ or \$V_{IN}-V_{TH}\$, depending on ...
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95 views

PFET to turn on/off system power

I have a Raspberry PI board connected to some external circuitry, and am using Microchip MCP23008 I2C GPIO expander chips to control external LEDs and motor circuitry. One important part of this ...
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32 views

Is IRFD 014 an appropriate FET for switching an array of (about 40) UV LEDs?

We have an array of UV LEDs. The LEDs are rated at 3.2 V – 3.4 V at 20 mA, and we plan to use a 5 V supply for simplicity. We will be using a dedicated 100 Ω resistor for each LED (the power ...
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241 views

How to make a 12V DC variable voltage supply with more than 30A output?

I have a SMPS capable of outputting 33A at 12V and I would like to make it have a variable output with full current potential, or close to it. Now, Is it possible to do it with a PWM-controlled ...
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1answer
67 views

Adjustable charge current from programming resistor for Li-Ion charger - how to change on demand?

I am designing a device which has an integrated Li-Ion battery (single cell, for simple low power portable digital device) and normally charges by way of a buck converter which goes from 12-16V ...
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1answer
48 views

Flyback converter current flow?

If you look at the flyback converter circuit above, the current only flows in one of the coils at any instant of time. What stops the magnetic field generated by the coil in series with the MOSFET ...
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56 views

Simulating a circuit consisting of MOSFETs

When simulating a circuit consisting of mosfets, when can you say that the MOS should be in cut-off, saturation. or linear (triode) region? Specifically a charge pump circuit utilizing PMOS.(refer to ...
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109 views

Do AC inverter H bridges ever get driven this way?

There's a google competition going on at the moment called the little box challenge. It's to design a very efficient AC inverter. Basically the inverter is fed a DC voltage of a few hundred volts and ...
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3answers
80 views

How hot can MOSFETs get before blowing up?

This is different from a lot of other stuff here, but I have a motherboard that has no MOSFET cooling, and when I touch them they burn my hands; they are probably 70-80C. I just want to know how long ...
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87 views

Homemade Brushless ESC

I am currently working on building a quadcopter with brushless motors. I decided to try to build the ESCs by myself with some MOSFETs. I am using an Uno as the main controller on the receiving end. ...
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28 views

Mosfet amplifiers mismatch effects comparison?

In Mosfet amplifiers we have Rd mismatch effect and gm mismatch effect .Which mismatch has the biggest,most important effect?
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43 views

Preference of MOS resistor as load in MOS inverter [closed]

Whys is a MOS resistor preferred over diffused resistor as load in design of a MOS inverter?
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2answers
84 views

Push-Pull driver for low side mosfet — is it a good idea?

I want to build an H-bridge to control a 36V dc motor (or possibly 48V but lets stick to 36V for now) The electronics that will control the H-Bridge (logic, etc) will run from a 12V ...
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120 views

Advantages of splitting a single NMOS transistor into two

Can anybody explain to me why in the schematic attached below that using two transistors is better than using only one transistor that is larger (longer)? I see that these two transistors are the ...
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107 views

Protect N-MOSFET against short circuit and overload

I'm using an Attiny and I want to connect a PWM pin to a N-Channel MOSFET in order to fade some LEDs, or switch a motor.Four wires are connected to my board: VIN, ...
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27 views

Find Id of NMOS

I need to find the drain current in the above circuit where I also know \$V_{TH} = 1\,\mathrm{V}\$ and \$\mu_{n}C_{ox} = 2\cdot 10^{-4} \frac{\mathrm{A}}{\mathrm{V}^2}\$. I'm just not sure about ...
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61 views

Active load using MOSFET

Good evening! I want to create an active load system where I can vary the PWM signal from the microcontroller to the control input of the MOSFET which is attached to a fixed resistive load. I want ...
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1answer
85 views

Safest way to make a high-voltage switch

First of all, I've dabbled in electronics on and off over the years. I have no formal training. I'm designing a vacuum tube guitar amplifier (seems like everyone is these days). I want to add a ...
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70 views

Can I use an N-MOSFET to turn off a voltage divider?

I'm using a simple voltage divider to measure the voltage of my battery. The battery will be in the neighborhood of 12V, and the uC runs at 3.3V. I don't need to read it often, and don't mind a few ...
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2answers
56 views

High frequency signal switch [closed]

I am trying to make a digital switch for a high frequency digital signal. As it's a voltage controlled switch, I am thinking of just using a MOSFET for it. What I am confused about is the bandwidth of ...
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1answer
73 views

Why does my 2N7000 show a gate current of more than 4mA?

I have the following circuit: simulate this circuit – Schematic created using CircuitLab The D1 is in fact a character LCD backlight (with 4.2V input voltage and a maximum current of ...
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52 views

Positive Photo Resist for lift-off & Negative for EBL?

I would like to know two things about Photo Resists (PR): How is positive photo resist used for lift-off? What is EBL and why negative photo resist is used in this case?
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53 views

Help with high side driver

I am building a non-isolated buck converter with a N channel MOSFET(2SK4017), I am using the FAN7382 High and low side gate driver. I just want to verify if my wiring is correct before I construct the ...
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30 views

Derivation of depletion layer in depletion mode in MOS Structure

First off, please understand my background. I am doing a course in Digital Integrated Circuits and following the book CMOS Digital Integrated Circuits and Design by Kang (3rd Edition). I barely have ...