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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111 views

How to make a computer with only copper? [on hold]

I have 60 lbs. of copper, and before selling, I intend on using all of its 60 lbs. of free electron movement to power a homemade computer. I would like to have MOSFETs connected to the copper ...
0
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1answer
39 views

MOSFET switch replacement not working

I'm using a PNP MOSFET to replace a physical button. When I ground the lead I've attached to bypass the switch, the action I need activates (a notification light comes on - it's the activator button ...
0
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1answer
65 views

using a MOSFET to switch a voltage lower than the gate

I'm using a p-channel mosfet to switch a 3.5V load, using a gate voltage that's ~5V. The gate goes from 5V to 0V, but the mosfet doesn't start conducting. Did I just fry the mosfet by having the gate ...
0
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1answer
63 views

DC motor - Transistor / Mosfet - Design

The one on the left seems to work neatly. But the right ones' motor goes way slower. Though, I did find the right one on the internet (and internet is always true). My thoughts: The amount of ...
2
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2answers
62 views

Is this the behavior of a broken mosfet?

I designed this circuit to switch on/off 8 solenoid valves for a programmable dancing fountain that I am building. The GPIO is coming from a Raspberry Pi. VCC is coming from a 12V deep cycle car ...
0
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0answers
20 views

Voltage-mode or Current-mode PWM controller?

I am trying to decide between a voltage-mode and current-mode PWM generator to connect to a gate driver IC to drive my power MOSFET. The PWM will be generated based on a current input to the ...
0
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0answers
18 views

Current-controlled PWM Generator with variable duty cycle?

I need to implement a variable duty cycle PWM generator with constant frequency (100kHz) to help drive a MOSFET. Is there such a thing out there in the market or is it something I need to build with ...
1
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2answers
125 views

Selecting a transistor for high-side switching at 5V with a 2A load current

I'm doing a high side switching of 5V 2A load and will be ON or OFF for long time(1-10 hours). Now I'm confused about which transistors should I use ? or MOSFETs ? Do I need heatsink ? I really ...
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0answers
32 views

Using p-Channel MOSFET as a Switch to turn load on / off via BeagleBone Black GPIO

Is this the correct way of using a pMOSFET as a High Side Switch? I need a Load Device to be turned on/off (Vin Pin). The Load Device requires 5v 700mA power to run. My logic is, when the ...
0
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2answers
54 views

Short-circuit primary side of a transformer to collect all the spikes at the secondary

Abruptly detaching a power source from a coil produces a back-emf: this is a well known fact. What I would like to achieve, in my experimentation, is to convey ALL the collapsing magnetic field to ...
1
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2answers
59 views

Mosfets cooled with Heatsink and fan?

For my circuit, I have mounted heatsinks to my mosfets to dissipate heat. I have below a crude drawing of how the heatsink/mosfet is placed on the PCB I was thinking to integrate a LM35 to measure ...
0
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2answers
45 views

What is the dependance of voltages in a MOSFET on its Performance?

The Wikipedia page says that (in context of scaling) To maintain performance, the threshold voltage (Vth) of the MOSFET has to be reduced as well. And also, this paper says, For high ...
1
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1answer
52 views

How to find the Q point of the NMOS trsistor in Voltage-Divider Biasing Circuit?

The following is the circuit needed to be analyzed to find the Q point(\$V_{GS_Q}, V_{DS_Q}, I_{D_Q}\$). \$V_{TN}=1\text{V}\$ \$K_n=0.5\text{mAV}^{-2}\$ simulate this circuit – Schematic ...
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0answers
34 views

MOSFET T-model question

In the attached diagram, I do not understand why the current source I becomes an open circuit and the voltage source Vdd becomes grounded. If someone can clear up this simple question for me, it'd ...
0
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2answers
48 views

Diode parallel to resistor on H-Bridge MOSFETs gates

I was looking at a TC4467's gate driver datasheet and there is one thing there that I haven't seen before when reading about H-Bridges. On the schematic of example H-Bridge motor control there is a ...
0
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3answers
70 views

Dual Mosfet Not Gate Getting Very Hot, Critique Circuit

I have put together this circuit from parts I had lying around, It is to invert a normally closed momentary switch to behave like a normally open. The switch is for a car and toggles a tail light. ...
0
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0answers
39 views

What are the two big transistors on a ESC

Looking at an commercial electronic speed controler for a brushless motor, there is two big transistors on one side. For controling a motor, you have to switch the current on three wire, so you need ...
0
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0answers
30 views

P-Channel FET Switching Time

I have a question about the circuit shown below. Specifically, I am looking to calculate the time that it takes to fully enhance the PFET and activate 3V3_SW1 after the control signal transitions ...
0
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5answers
63 views

Reducing the voltage drop on a simple comparator driving a MOSFET to avoid LiIon overdischarge

I would like to use a LiIon cell recovered from an old laptop to power my bike light (a bulb one, 2.4W 6V). I thought about using an opamp controlling a MOSFET to avoid overdischarge (MOSFET ON for ...
0
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0answers
32 views

Field Excitation of synchronous motor with MOSFET+ Arduino ( MOSFET accessories design)

Abstract: I am trying to make an automated system, that monitors the system's voltage, current, all powers and power factors. This data is wireless sent to a substation(prototype model, imagine=master ...
0
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0answers
8 views

How to add different models for different transistor in tanner t-spice?

I am working in tanner 15 at 180nm technology. I have a circuit in which transistor have different threshold voltages so is need to define model file for each transistor how to do that .... I tried ...
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1answer
45 views

What could be the target applications for these BJTs?

NXP recently introduced a new family of BJTs with switching capabilities of up too 100V, 10A , see "The toughest bipolar transistor - 100 V in LFPAK/Power-SO8". I cannot think of a switching ...
1
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1answer
103 views

Do MOSFETs have a diode built into them?

I have noticed that a MOSFET symbol has a little diode in it (or at least what looks like a diode). Does this mean I do not have to worry about using a diode in a circuit that runs a motor using one? ...
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36 views

MOS differential pair simple question?

In the MOS differential pair why is Vg1=Vg2=Vcm? I always read in exercises relating MOS pair that "We assume Vg1=Vg2=Vcm" but why are Vg1 ,Vg2 and Vcm equal with each other?
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18 views

Solenoid Circuit: MOSFET switch help

I am trying to operate a 5V solenoid using a IRLZ44N power MOSFET. My problem is I cannot get the MOSFET switch to work. My circuit: 5V into solenoid and diode (1n4004) in parallel into the drain of ...
0
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0answers
52 views

Mosfet small signal input resistance from source

Considering the T model of MOSFET for small signals I want to obtain the input resistance from source to gate. simulate this circuit – Schematic created using CircuitLab The current ...
0
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2answers
72 views

What is the purpose of the resistor on this MOSFET's drain?

Shown in the schematic below is a typical MOSFET driven by a BJT. I know the purpose of almost everything here, except for R4. I just can't figure out what the resistor on the MOSFET's drain is for Is ...
0
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1answer
31 views

Operation of this CMOS Logic

I found this CMOS circuit in my textbook. It says that when input voltage is 0V, the output voltage is 0V, and IDN and IDP are both zero. I think that the output voltage is 0V due to some form of ...
0
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2answers
59 views

N-Channel MOSFET as 12 VDC switch

A little background: I have a 12 VDC "cigarette" socket in my car which is a non-switched circuit (so, always on). I'm in need of a switched socket, whereby power is cut when the car is not running. ...
3
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1answer
98 views

Using a MOSFET to switch a High Voltage on a Capacitive Load

I am trying to bias the filament of an electron gun to -575 V, but I need to switch it on and off using a TTL signal. I have an idea for how to do it, but I would like to know if it will work before I ...
0
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1answer
62 views

Switch between voltages

i already posted a similar question before and i still don't know exactly how to wire up things. I will try to explain better. I have a pc power supply and a pc fan that works between 5v and 12v. All ...
0
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2answers
23 views

Achieving higher current at the lowside MOSFET to pulse LED

I have attached the following circuits which i have been developing overtime. The OBJECTIVE is to get as high as possible a current at the gate of the MOSFET (VF1) to achieve faster pulse times of ...
2
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1answer
64 views

MOSFET orientation in schematic

I'm working on an ultrasonic transducer driver circuit, originally designed by Lindsay Wilson, and I'm currently seeing spikes at the switching junction. I'm running out of things to troubleshoot, so ...
0
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1answer
39 views

Gate biasing of common source MOSFET amplifier

I am trying to fully understand the following circuit and have some questions about it. Some preliminary info is that this is an audio voltage amplifier specifically for guitar use. Now overall, it ...
0
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0answers
32 views

Question on large signal MOSFET DC Circuit Analysis

The question is asking us to prove that the PMOS is indeed operating in the saturation region. For part (iii) , I've found that VG = 6V by voltage divider law. Since IG = 0 , then ID = IS. In other ...
0
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1answer
40 views

Voltage source connected to a MOSFET source

This circuit simulate this circuit – Schematic created using CircuitLab where M1 is an n-channel MOSFET, is said to be incorrect. If the voltage Vin should be imposed to the source ...
1
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1answer
26 views

Carriers in the channel of a MOSFET

The channel formed in a MOSFET which is ON consists of carriers. From where do theses carriers come? Do they come from the Source/Drain regions? Thanks.
0
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1answer
59 views

Should ground be shared between MOSFET gate, draing and source?

I'd like make a voltage buffer with MOSFET STD12NF06L-1 IPAK - STMicroelectronics Configuration of Gate and ...
0
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0answers
34 views

Help Converting a PSPICE MOSFET .LIB to an LTSPICE .SUB

I am designing a buck-boost regulator for a course at school and I would like to use the OnSemi ntk3139p PMOS transistor. OnSemi provides a few spice models for this part and I am getting stuck ...
0
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2answers
52 views

can NPN transistor be used when sinking current?

so to give a little bit of background, I want to experiment with led matrixes. I have multiple Arduino Nano boards, and have done small projects (9 LED bank with simple animations). So I know that ...
1
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1answer
35 views

Might I be better off using a TIP122 Darlington than a FQP30N06L MOSFET?

This is a followup to: Simple ESD protection for MOSFETS I built the circuit described in the above post using FQP30N06L MOSFETs and after several hours of testing two of the MOSFETS died at nearly ...
0
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1answer
30 views

Rise time and fall time calculation of an integrated switch?

Following the analysis regarding the selection of buck converter for my application (Buck converter efficiency Vs load current:). Now I am trying to estimate the power dissipated in the integrated ...
-1
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2answers
91 views

Theory of operation for discharging filter capacitors with a MOSFET switch [closed]

Our teaching assistant showed us this circuit, saying that the MOSFET acts as a switch. When the power supply is OFF, the MOSFET allows the filter capacitors to be discharged via the switch circuit. ...
2
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0answers
79 views

Switch between power supplies with a mofset

i'm new here and my knowledge in electronics is basic, so what i'm trying to do is to switch between two power sources, one at 5V an other at 12V, i already made a circuit that kinda works, but i have ...
2
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1answer
60 views

Vias under thermal pads

I'm working on a design with MOSFETs and with the LT4415 device. The MOSFETs should dissipate an average heat of 0.45 W (with peak at 2 W but just a couple of seconds with several minutes to ...
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2answers
85 views

Why are MOSFETs better than BJTs in application of Voltage Controlled Resistor?

Why are MOSFETs better than BJTs in application of Voltage Controlled Resistor ? Thanks for your responses.
2
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2answers
47 views

DC analysis of common source MOSFET circuits to find gate voltage using different power supplies

simulate this circuit – Schematic created using CircuitLab strong text I am solving problems on DC analysis of MOSFET circuits. We are supposed to find various parameters like Id(Drain ...
0
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1answer
51 views

PSpice cascode mosfet design not working properly

I'm making a Common Source amplifier using a mosfet and then comparing that to the same basic setup but with 2 mosfets in cascode. However I get a nearly identical response for both circuits. I'm ...
0
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1answer
38 views

please help me choose power mosfet for multilevel inverter

I am doing my senior project on cascaded multilevel inverter. I am planning to use MOSFETs as switches in my project.Please kindly give me instructions and respective formulas for getting right ...
0
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2answers
90 views

CMOS: dual of cascode circuit

If this is a differential folded cascode CMOS amplifier simulate this circuit – Schematic created using CircuitLab (where the "first" stage is nMOS and the "second" one is pMOS), can the ...