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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17 views

12v/24v 125amp battery charger fets [on hold]

The fets are hitachi and are marked 78455. Need a suitable replacement or access to the originals. Have searched the internet and equivalent handbooks without any success.
3
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1answer
93 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 ...
0
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3answers
70 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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1answer
62 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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39 views

Preference of MOS resistor as load in MOS inverter [on hold]

Whys is a MOS resistor preferred over diffused resistor as load in design of a MOS inverter?
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2answers
66 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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1answer
100 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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89 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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1answer
25 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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1answer
45 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 ...
0
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1answer
84 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 ...
0
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1answer
64 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 ...
2
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1answer
68 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 ...
5
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1answer
45 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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1answer
38 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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23 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 ...
2
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1answer
71 views

MOSFET H-bridge design

given the circuit below to be used as a H-bridge with AVR PWM. Is this a good desing to use? What can you recommend? I already built something like this but without the resistors. ( and so burned ...
3
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2answers
131 views

How to protect a P-channel MOSFET when driving a motor?

I want to switch a 12 V DC automotive fuel pump in a bench test rig using a P-channel MOSFET, as follows: simulate this circuit – Schematic created using CircuitLab This is a simple ...
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2answers
101 views

RGB LED strip, powered by an ATX PSU and controlled by PWM, makes my speakers buzz with Arduino connected by USB

I've not much idea about electronics, but I managed to do some little projects in the past. Now I'd like to place some RGB LEDs in my desktop PC windowed case. For that, I bought a 5050 SMD strip with ...
4
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3answers
115 views

Can I use a N-MOSFET to switch lower voltage signals?

I'd like to have a 12V signal as an input to a microcontroller, but it can only handle 5V on the input pins. This circuit will be used in a truck, so the "12V" signal can vary by quite a lot. My ...
2
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1answer
109 views

Specification Clarification for FETs

I use a MOSFET in my project, and I don't know what model of MOSFET I need. I do have a list of specs, but I don't know what they would be called on the datasheet. I need some help translating my ...
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2answers
55 views

PMOS, NMOS length width concept for low power circuit

Why for low power consumption width of NMOS taken same as length of feature and Width of PMOS taken as 2.5 times width of NMOS ? e.g for feature size 180n width of NMOS 180n and width of PMOS 450n. Is ...
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1answer
69 views

Which kinds of FET have a body diode

I need to detect small high and low peaks in the battery voltage while in use. The goal is to help estimating the end of the battery charge by its change in impedance, since my circuit uses the ...
0
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1answer
65 views

MOSFET controlled DC motor too slow

I want to control a DC motor using a P-channel MOSFET. I tried the motor with a 5VDC power supply. It works perfectly and speeds up in no time. I measured the current flowing through, it's around ...
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3answers
103 views

Circuit to switch about 5W of 12V using CMOS logic inputs using N-channel MOSFET?

I want to switch some 12V landscape light LEDs, totaling about 5 watts, using MOSFETs. I thought I had some logic level N-Channel MOSFETs lying around, but apparently not. What I have is several ...
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1answer
58 views

MCU Output Driver Verification

I am creating a circuit in which a MCU (STM32) must drive 12VDC outputs, and wanted to make sure there wasn't anything missing in my driver circuit for the outputs. ...
1
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1answer
38 views

Custom device with multiple gates tied together in Eagle

I'm trying to create a transistor array device in a small library I'm working on in Eagle. The device has five P-Channel MOSFETs. The source of each MOSFET is internally tied together and connected to ...
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1answer
73 views

Is a DVD sensor a photodiode or an array of them?

Is a DVD sensor just a photodiode or an array of them? I need to know if it is a CMOS with an array of them or just a single sensor.
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2answers
282 views

Why is there so much overshoot in my LED circuit and how do I prevent it?

I'm trying to PWM a 5 meter RGB LED strip with a microcontroller. With this setup: simulate this circuit – Schematic created using CircuitLab I have built it on a breadboard and probed ...
3
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1answer
149 views

Linear Regulator: MOSFET vs BJT

Currently I am doing a project on a voltage regulator. Can you tell me some advantages of MOSFETs over BJT? Apart from a higher power loss, I can not find much. In control engineering it is much more ...
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52 views

Driving LED from two supplies

In my design, I want to drive a LED using two different supplies depending on the control signal for n-mosfet. One of the supply will be disabled at boot-up. P MOS will be used to enable supply for ...
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1answer
120 views

MOSFET resistance

I'm trying to understand how MOSFET resistances work, but I'm seeing a lot of things that don't always fit together (probably due to my lack of understanding). Specifically the amplifier ...
0
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2answers
74 views

Can a high voltage difference force a MOSFET open?

I'm going to assume the obvious answer is no, but I figure I should check with the experts before I go off and waste a bunch of my time. Say you have several MOSFETS in a row controlling the flow ...
0
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1answer
77 views

driving a control pin to ground with different voltages

I'm using a 3.3V atmega2560 to disable a switching regulator that's operating on a ~12V battery. The EN pin on the switcher is pulled up to the battery voltage, and needs to be driven to ground to ...
3
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2answers
259 views

Does a logic-level P-MOSFET need a gate resistor?

I'm quintuple checking something I'm about to order from a PCB house, so bear with me. I'm using a P-channel MOSFET to power on/off a GPS chip. The chip's grounding is complicated, so I prefer to ...
5
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1answer
136 views

Why have my MOSFET drivers blown in this H-Bridge?

I've built a discrete H-Bridge circuit to run a reasonably beefy 12V windscreen wiper motor. The circuit is below (EDIT: see here for a bigger PDF, StackExchange doesn't seem to let you expand the ...
0
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1answer
57 views

Heating coil over-drawing current

I am currently designing a circuit that includes a nichrome coil used as a heating element. The wall adapter is 25V 5A DC, which leads to different buck converters that takes it down to the ...
0
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1answer
60 views

Inform microcontroller that the analogue circuit is powered up

Basically, I want to pull-down the microcontroller pin if some analogue circuit is powered up. The analogue circuit power is 9V, 1.6A. The idea I have is to use something like IRLZ24N MOSFET, connect ...
0
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1answer
94 views

n-channel MOSFET source load alternative

I'm trying to drive some RBG leds using MOSFETS. Let's say I have 2 individually RBG LEDS, each controlled by 12V, with each R, B and G with its own output to GND. What I want to control, is to be ...
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1answer
36 views

overdrive voltage margin to enter MOS into subthreshold and saturation region

What is the equation for Vgs value for any MOSFET in such a way that, Below Vgs, Mos is in subthreshold region, Above Vgs, Mos is in saturation region?
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110 views

2n3055 replacement with MOSFETs

I have searched a simple circuit diagram for a 12v to 220v voltage inverter. The circuit has two 2n3055 transistors and I presume it is used for switching. Can I replace them with IRFP250 MOSFETs ...
0
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61 views

How to use LM56 to switch on/off a 2kW heater using a MOSFET

I have an oil heater at 220V/2000W so lets say 10A (maybe more when it starts?!). I was thinking of creating a circuit to switch the oil heater on/off with a LM56. Is it possible using a MOSFET ...
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1answer
115 views

MOSFET Amplifier?

I'm trying to create an amplifier circuit using a n channel MOSFET and I can't seem to get the results I'm looking for. I'm trying to amplify an AC signal up to the +/- Vcc but I keep getting strange ...
0
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2answers
77 views

Optoisolation and Mosfet combo

I want to switch a Thermoelectric Peltier Cooler (TEC1-12705) (12V - 77 Watts) using an Uno. I am an engineer but not an EE so I could use some guidance on circuit setup. There was a very good ...
0
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0answers
55 views

Strange output waveform of the high-side load of MOSFET

everyone. I am using a MOSFET as a switch to drive a laser diode. I input a periodic signal to the Gate of the MOSFET and I obtained a strange high-side load waveform. Here is my schematic. When I ...
0
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1answer
49 views

Unexpected results in Multisim

I am in the process of selecting a N channel MOSFET for switching purposes and thus, tried out this simple circuit in Multisim. But it seems that the MOSFET conducts in the cut off mode and remains ...
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2answers
185 views

Power switch with slow control signal

I am trying to switch on and off a circuit that draws about 0.8 amp at 12 V. The obvious choice is to set a MOSFET. The problem is that the control signal (the one that goes on the gate of the MOSFET) ...
0
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2answers
154 views

Make a zener diode out of a MOSFET

Does anyone know if its possible to wire up a MOSFET transistor as a zener diode? I have been happily making normal diodes from my MOSFETs by shorting the gate and the source simulate this ...