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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60 views

Why are my LED weak?

I am beginner enthusiast. I was trying to make lights under my bed by following this tutorial: http://aruljohn.com/blog/raspberrypi-christmas-lights-rgb-led/ It worked for me with a 1 meter color ...
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0answers
44 views

Sedra & Smith Microelectronics 7th edition Problem 7.8

The answer is 0.712V, but how?
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1answer
43 views

MOSFET Drain Voltage

I am trying to simulate a single NMOS, I calculate the I_ds but I need the voltage of the drain terminal. Should I multiply the I_ds value by a resistance value? Is this resistance constant? If not ...
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0answers
30 views

Relay vs Switching Voltage Regulator

I have a microcontroller Atmega328p and some sensors like Dht22,Lm35,switching voltage regulator and a 9V battery.When my microcontroller is on sleep the total circuit consumption is about 11mA.That i ...
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1answer
18 views

Arduino Uno, HC-06 Bluetooth & RGB LED Strip on the same 9V Power source

Hello! I am a complete amateur when it comes to electronics so forgive me for any misconceptions. I am trying to design a circuit that will power an RGB LED Strip (here depicted by a single RGB LED)...
2
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1answer
54 views

Searching for exotic SOT23 P-channel mosfet where source drain swapped

Due to an error in the layouting process a batch of PCBs has to be scrapped. Instead of the standard pin assignments: 1 - Gate 2 - Source 3 - Drain we used: 1 - Gate 2 - Drain 3 - Source As a ...
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0answers
37 views

MOSFETs as Switches

How could you use a MOSFET as a switch to drive a motor of 12-40V and 240W? As well as would it be able to operate at high temperatures (about 150degC)?
4
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1answer
88 views

Transistor PWM Generator (No ICs) for practical application

I want to produce a good quality PWM signal with transistors(BJTs, FETS, etc..). I do not want to use an IC at all(learning to use transistors properly). I'm currently using a BJT Astable Mutivibrator ...
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0answers
20 views

How to switch on/off 8mm(1w)led connected in series? [on hold]

I have 8mm led connected in series(50 nos) where each led take upto 1w . I need blink the led for 3sec once . I need a application to be done like this I did this by using 555 timer ic and using ...
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2answers
51 views

Power Dissipation of Power Mosfet

I am doing power dissipation of a power mosfet. My design requirements are :- 20A @ 12-20V (Ambient temp will be around 50 deg Celsius) The mosfet I am using is :- http://aosmd.com/res/...
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0answers
136 views

Cheapest Raspberrypi (or MCU) on/off power supply latching issues

Together with a friend we tried to implement the following schematic we found online after a quick search for "simple raspberry pi on/off latch power supply": Then we simulated the above schematic ...
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1answer
39 views

How to calculate the dead time to incorporate in the complementay PWM input to an H-Bridge designed using MOSFETs?

I am working on making an autonomous robot. Right now, I am involved in designing an H-Bridge using discrete components for my robot. I am almost done with the H-Bridge design, and want to test it ...
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0answers
78 views

Why do I get maximum output from OpAmp

I adapted a circuit for a voltage controlled isolated resistor using a LM324 OpAmp, a Darlington NPN (MPSA14), and a Fairchild Opto-FET (H11F1). The mission is to provide a 0 - 10K isolated ...
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1answer
81 views

Multiple fingers vs single finger layout (MOSFET transistor)

Please, provide a summary of advantages and disadvantages of a transistor layout with multiple fingers (MF) vs single finger? When laying out a MOSFET with a particular width and length, in an EDA ...
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1answer
44 views

MOSFET connection within oscillating circuit

I'm working on a group project, where for one part of the circuitry we have a "Royer Oscillator", which can be turned on/off via an N-channel MOSFET (IRFU4105ZPBF) at the input (whose gate is ...
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2answers
59 views

what is critical in handling Heat dissipation of mosfet - Source or Drain!

I am working on a board which is connected to a DC power source of 12V/20A. To control the power to the load , I am using a PMOS as high side switch as shown below :- My Doubt is, from power ...
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33 views

microcontroller suggestion [closed]

my requirement is 2 on/of buttons 3 buttons use for 3 steps of motor speed control High medium and low. and they also remote control please suggest a microcontroller which is suitable and low ...
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1answer
47 views

Applications of transistor feedback

I saw the following circuit in an electronics exam. I think the feedback network consists of a transistor (M3) and a resistor (Rf) and the feedback type is current-current; Is this analysis correct? ...
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0answers
26 views

Recommend MOSFET For PWM Operation [closed]

I am looking for a N-MOSFET for fast Switching( PWM ) to control the speed of 5V DC Motor. I will be providing a Voltage of 5V (Voltage to be provided to DC Motor) at the Drain, and connect Ground at ...
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3answers
57 views

hybrid-π model VS T-Model for MOSFET and BJT

1) when to use T model for MOSFETs instead of hybrid-π model? 2) when to use T model for BJT's instead of hybrid-π model?
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0answers
44 views

Class D Output Stage - MOSFET turn off diode

I am currently working on a class D audio amplifier. During this process I've come to have a pretty decent prototype, which I now wish to improve. In this manner I wish to improve especially the ...
3
votes
1answer
117 views

Is the 555 necessary here, or can I just use an op-amp?

Context: The circuit's main input is a line-level audio signal from a computer. Every time that something loud happens in the audio, I need the solenoid to activate for about 100 ms. The first ...
2
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1answer
34 views

In MOSFETs why is the gate-body inversion layer voltage able to create a conducting channel, yet the same source-drain voltage not?

I have very little experience with electrical engineering, so please bear with me. I was hoping to get a qualitative explanation as well as pointers to the maths/formulas which could formally explain ...
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2answers
867 views

I was explaining a transistor to someone, and I realized: I don't really understand several key concepts at a low level. Help?

(Surplus story removed.) I was explaining MOSFETs, CMOS, and logic gates to someone and realized I didn't grasp some concepts as well as I thought. It culminated when he drew a single transistor, ...
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1answer
20 views

How to use BSIM3v3 capacitance for hand calculation?

As you all probably know, capacitances in BSIM3v3 are just the partial derivatives of the terminal charges with respect to the terminal voltages. They are not physical two terminal capacitors. Cij = ...
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42 views

My nMOSFET (maybe non existent). N canal with Vgs=0?

if I realize the following nMOSFET: is it possible to obtain n canal with \$V_{GS}=0\$? Thank you for your time.
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67 views

Is this circuit possible? using same pins for active low/high

I designed this circuit : The goal is to use A B C ports on a pcb, to perform as: output- active low/high, or as an input. (not in the same time) All Fets are <...
4
votes
2answers
75 views

Why is there a resistor in a cmos X-OR gate?

While reading up on logic gates i came across this image on Wikipedia: According to the article, the resistor on the supply voltage for the inverter is necessary to ensure that no current is leaked ...
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1answer
71 views

Why L6743D MOSFET driver is not working properly?

I've started to build a brushless driver by using some Power MOSFETs and some MOSFET drivers, in order to drive the Power MOSFETs. I have connected the chips as shown in the application circuit (page ...
2
votes
2answers
78 views

MOSFET as a switch to control 12 solenoid valves using arduino

I am working on a project that requires me to control 12 solenoid valves using arduino. I find out that I can use MOSFET as a switch to turn on or off my solenoid valves. I have minimal experiance in ...
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0answers
40 views

MOSFET gate capacitance in strong inversion

This lecture (page 4 and 5) said about gate capacitance of a MOSFET in various operating condition. From the table below, as you can see in strong inversion \$C_{ox}\$ and junction capacitance \$C_{...
0
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1answer
38 views

Can someone help me fix this water level controller?

A, B and C are the prongs that stick into the water at 1/4, half and full respectively. D is used to provide the current to switch on each of the prongs as the come in contact with the water. That ...
4
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4answers
810 views

Do power MOSFETs have significant disadvantages over normal MOSFETs?

I have noticed that many power MOSFETs are cheaper, have a much greater \$I_{D}\$ and \$V_{DS}\$, and have comparable \$R_{DS(on)}\$ and \$V_{GS(th)}\$ values to normal MOSFETs amongst other ...
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1answer
24 views

Channel to bulk capacitance in inversion

This lecture (page 11) said that as Vgs increases further, the inversion layer forms and the channel to bulk capacitance is “shielded”. So the channel to bulk capacitance is 0. Could anyone explain ...
2
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1answer
41 views

Is the bulk output deliberately used in DRAM cells?

Regarding the structure of a DRAM cell with a MOSFET and a capacity, why does activating the word-line make the transistor connect through? As I learnt, the MOSFET becomes conducting if UGS >> ...
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0answers
36 views

How to distibute power between MOSFETs and resistors in current limiter cirquit

I thinking about making some sort of not-very-big-power hi-side current+voltage limiter, using cheap china SOT-23 P-chenel MOSFET like IRF9310PBF, BSC030P03NS3G or AO4407. But in some user cases ...
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2answers
22 views

Which CMOS SPICE model should I choose?

I need to simulate digital circuits which have custom gates. For now I am not concerned about the specific CMOS technology, the transistor Length and Width, etc. I only need to glue NMOS and PMOS ...
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2answers
62 views

Are parasitic capacitance \$C_{gs}\$ and \$C_{gd}\$ parallel in a MOS?

The picutre below shows the parasitic capacitance \$C_{gs}\$ and \$C_{gd}\$ in a MOS transistor. Can we consider that the two capacitors are in parallel in this case?
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2answers
63 views

Ultra low power input ORing/power muxing

I'm working on a project with three power inputs and I need to automatically switch between them (favoring the highest voltage). There are plenty of posts on this topic (especially on this exchange) ...
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4answers
105 views

Rapid Reverse polarity

This is the circuit for reverse voltage protection, R2 is the load of a motor. The problem is that there is a test where the changing of polarity is very fast ( <5ms) and the MOS burns. Power ...
4
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2answers
189 views

what is the tempreture at which the thermal limit of an amplifier is reached

Introduction: I am upgrading a "power amplifier" that a fellow engineer has designed , my job is to add thermal protection against failure in prolonged use (or operator miss use). The package of ...
1
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1answer
53 views

What type of FinFET is this? It is an example file of Sentaurus TCAD

As as I am totally new to TCAD software, I'm unable to parse the code. My doubts are as follows: 1) Whether it is a SOI Finfet? 2) Why am I only able to see half structure at the last node? ...
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0answers
69 views

Audio POT with FET and PWM

I've been trying to build a simple audio pot to be controlled with PWM with an arduino, but I'm not sure why it doesn't work. I could do it with a LED (not directly which is simple, but with a FET), ...
0
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1answer
65 views

Help in chosing Mosfet [closed]

we have a circuit using a DAC http://www.analog.com/media/en/technical-documentation/data-sheets/AD5593R.pdf so basically the DAC output voltage is from 0 to 5V This DAC needs to finely control ...
-1
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2answers
43 views

Mosfet driver(Pin configuration)

I would like to know what Vcc(supply voltage) and Vin(input voltage) do on Gate driver. Here is the datasheet. http://www.ti.com/lit/ds/symlink/tps2813.pdf
3
votes
3answers
209 views

What design decisions must I make to select a suitable P-Channel MOSFET

I need a PFET with a logic level gate to trigger a power connection to a hobby servo that pulls more current than my MCU pin can handle. The requirement is simple but I'm trying to understand how to ...
0
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1answer
54 views

Driving 4 100mA motors using GPIO pins and BS170s

I'm trying to drive 4 tiny vibrating motors which draw 100mA at a maximum of 5V. I need to control them using PWM from the GPIO pins and would like to accomplish this in the smallest form-factor ...
1
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1answer
97 views

How MOSFET gate capacitances (Cgs, Cgd) are calculated?

I have read somewhere that the gate capacitance (Cgs, Cgd) of a MOS is calculated as below: Strong inversion: Cgs=(2/3)Cox.W.L + Cov Non-saturated: Cgs=Cgd=(1/2)Cox.W.L + Cov where Cov is ...
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0answers
40 views

Switching ON/OFF the enable input pin of TPS63060 DC-DC switching converter

I need to make an ideal switch to turn ON/OFF the EN pin of a Texas Instruments TPS63060 buck-boost converter. Now, my PCB has got a MC14093B "Quad 2-Input “NAND" Schmitt Trigger" to drive the gate ...
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0answers
16 views

Replace hybrid-pi model with proposed Thevenin model

This lecture (page 10) shows how to replace hybrid-pi model with proposed Thevenin model. Could you tell me how to calculate \$A_{v}\$ to get the result as in the page?