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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1answer
14 views

mosfet switching high frequency ac

I am trying to use MOSFETs to switch AC power. Here is my test circuit: simulate this circuit – Schematic created using CircuitLab If I put DC or low frequency ( < 1000khz) across the ...
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1answer
33 views

MOSFET Vg not zero?

I have this simple circuit with a 5V power source, a MOSFET, a diode and a resistor. With the diode already blocking, how come Vg isn't 0V but 2.06V? If the circuit is modified to become this, Vg ...
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1answer
25 views

Correct MOSFET choice for brushed DC motor

I'm looking for a few MOSFETs for a really small motor. This question is exactly what I am asking but I'm afraid this might be marked as a duplicate. Basically, I have really small motors rated more ...
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1answer
42 views

High side driver and Low side driver

Can anybody help me in understanding exactly what a high side and low driver is? Where they will be used? and why? How is their selection done? It will be really helpful..
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2answers
104 views

Trying to understand why MOSFET is not switching

I am experiencing an issue with the N channel MOSFET below: The MOSFET is not switching at all and I would like to understand why. I have used a similar circuit to control an LED and it always ...
-1
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0answers
46 views

13.5 MHz amplifier 20 W

I need to design an amplifier that takes a 13.5 MHz signal (10 mW, 1 Vpp) and amplifies it to 20 W for a coil. I'm thinking I'll use an op-amp to drive a Mosfet, but I don't know much about designing ...
0
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1answer
53 views

Driving MOSFET gate using PIC

I would like to drive a MOSFET gate using 12V (in order to reduce the drain-source resistance). Using the answer from a few post i've read I have come up with the following circuit. Will this circuit ...
-2
votes
1answer
47 views

Mosfet identification

What mosfet is this? I know that it's N-Channel but where's the side of Source and Drain? I think, Source it's at right side, because of shifted Gate line... What's the usage of the two opposite ...
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0answers
32 views

BJT or Mosfet for PID

I want to build a PID controlled Servo valve. I can't choose driver transistor which is best for linearity , fast response, working life. BJT or Mosfet? This is the amplifier schematic In the ...
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2answers
63 views

MOSFET driving MOSFET for reduced reduced Rds [duplicate]

I am using a PIC to drive the gate of a logic level MOSFET. Although the 5V logic output of the pic is sufficient to exceed the threshold voltage I would like to drive the gate using 12V to reduce the ...
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4answers
71 views

Using transistors to prevent short circuit / current limit

I am designing a circuit where I want to protect Q1 from current overload and popping in the event that Rl is a short. The length of wire in a short circuit situation is 0.7 ohms. Usually Rl is 10 ...
-3
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0answers
33 views

h bridge with 4 N type mosfets [closed]

i have some kind of big problem and i need kind of a fast solution. i want to make an H-bridge with 4 N-type mosfet(what available now is rfd14n05, but i can use any kind of n type mosfets). but i ...
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votes
2answers
24 views

how to find the current sensing resistor value for linear mosfet?

I am new to this field, that's why i am trying to find the value of current sensing resistor for monitoring the drain current of MOSEFT which is used in this picture. as an electronic load, the ...
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0answers
32 views

Low Voltage Switch/ Cut off for 5S lipo

Hi Could anyone please provide a schematic with component specs/values for a Low voltage switch / cut off using a mosfet. I have a power supply consisting of a 5S lithium battery pack and its ...
0
votes
1answer
23 views

BUZ71 MOSFET seems to be not fully activating

I'm controlling a coil running at 32V from a microcontroller running at 5V via a BUZ71 N-Channel enhancement mode MOSFET. The coil has a resistance of about 30 ohms and it draws about 0.6A at 32V. I ...
13
votes
4answers
459 views

Designing a *linear* MOSFET driver stage

I'm looking for a MOSFET driver circuit that can be placed between an op-amp and a power MOSFET to operate the transistor as a linear amplifier (as opposed to a switch). Background I'm developing an ...
0
votes
1answer
90 views

Can I connect a MOSFET to an Arduino directly?

I have the following electromagnet and plan on connecting it to the following MOSFET which will be controlled by an Arduino (I'm thinking analogue or PWM). Do I need any other parts (resistors etc.) ...
0
votes
1answer
48 views

Controling the Voltage of alternator

I want to design a circuit to control the output voltage generated by car alternator in a way that it shouldn't allow voltage to exceed 15V and also when the output voltage of alternator is less than ...
0
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0answers
64 views

Resistive feedback on MOSFETs

simulate this circuit – Schematic created using CircuitLab Two quick questions ==== So, I've modeled several MOSFET-based amplifiers and a lot of them are based on this assumption: if ...
-1
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1answer
35 views

What will be this CMOS logic circuit's Truth Table?

I encountered with this MOSFET logic circuit and asked to find which logic gate it represent. simulate this circuit – Schematic created using CircuitLab How can I calculate it's logic ...
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2answers
39 views

Low voltage drop transistor for Arduino

I am using a MQ135 gas sensor in my project. It takes a max of 200ma and I have connected the Arduino to a battery so I can disable it when needed to save battery. I am using a transistor for that but ...
1
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1answer
63 views

BS170 Mosfet equivalent for PWM application

I'm currently using a Mosfet BS170 to drive LEDs from a 3.3V 1Khz PWM output. The problem is I would like to use more current (something around 2A max at 12V Max) than the 500mA allowed by the BS170. ...
10
votes
3answers
349 views

How can I measure gate capacitance?

Is there an effective way to directly measure the gate capacitance of a power MOSFET, like say the IRF530N? The way my circuit is behaving would indicate that the effective gate capacitance is ...
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2answers
41 views

compare high power mosfet for high power load

I'v been searching mosfet for high power load project (DC 110V 100 Amp) and I found Fairchild FDL100N50F (TO-264) with maximum Power Dissipation 2500W. According to data sheet, the Max SOA DC ...
2
votes
2answers
60 views

Is it safe to “top up” bootstrap capacitors using a charge pump?

This document from TI describes a method to allow use of bootstrapped N-Channel MOSFETS at high duty-cycles, by keeping the bootstrap capacitor "topped up" with an external charge pump, separate from ...
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0answers
71 views

How can I perform power source switching using a P-channel MOSFET?

I am trying to build a power source switching circuit for an Arduino-based GPS tracking device/application. One power source is a solar-cell (rated at 1.5W and 6V) and the other is a 3.7V lithium-ion ...
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0answers
38 views

Power Mosfet and IGBTs

Can somebody explain me the difference between power semiconductors and traditional ICs..and within power semis the difference between IGBTs and Mosfets. a detailed answer would be really ...
2
votes
1answer
166 views

N-channel MOSFET connection

I'm studying this circuit below which in fact uses a N-channel MOSFET in a power line, with source at the supply voltage and drain at the load. Why the source is the input supply voltage and not the ...
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2answers
44 views

How to use arduino and P-channel & N-channel MOSFET to control voltage to PT2264 address pins

Im looking to control a PT2264 RF transmitter module from an arduino so that I can transmit to different receivers. To do this I need to supply either +12v or 0v to the various address pins of the ...
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0answers
32 views

JFET n and p channel low frequency response? [closed]

So suppose whe have an amplifier with a transistor JFET ,n channel. I need to do the low frequency analysis and explain the parameters. Problem is,in my book there is this exact same analysis but ...
0
votes
1answer
35 views

MOSFET transconductance variation

My book says that by varying Vgs the transconductance varies in a non linear fashion (this all happens in the "linear" or ohmic region of the FET) and it is constant in the saturation region.I just ...
1
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2answers
143 views

Can I bench test a N-channel MOSFET with battery, oscilloscope, and arduino alone (no applied load)?

I am having trouble getting some MOSFETs I have to behave like I expect, but I am just testing them with an oscilloscope, battery, and appropriately high voltage digital output on a microcontroller. ...
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2answers
75 views

What should I do if my MCU output is higher voltage than the Max Gate V on my N Channel MOSFET?

The V(GS) Gate to Source Threshold Voltage for a MOSFET I would like to use is listed as Min 1.5, Typ 1.9, and Max 2.3V. I am working with a Teensy3.1 that outputs 3V on the PWM pin. Do I need to ...
1
vote
1answer
72 views

Mosfet overheating under pwm

Here the schematic of a very simple circuit I know I don't have the flyback diode on the motor. And the MIC4422 is flipped in the schematic. I want to control the high power motor with this high ...
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0answers
34 views

Mos amplifier mismatch

There is a question on my textbook..Analyze in a detailed manner the effects of the mismatch in the differential amplifier MOS.Which one has a dominating effect according to you and why? I know how ...
2
votes
1answer
53 views

AVR and MOSFET gate resistor

I am driving a MOSFET with AVR using PWM for controlling a motor. I have a 4K7 pull-up resistor on the gate. My question is, do I need a resistor in between the AVR pin and the gate? (The mosfet is ...
0
votes
2answers
90 views

MOSFET with *actual pin* for body

I have always thought that MOSFETs have four pins [see wikipedia], one of them connected to the body (i.e. substrate). However, when trying to order some, I have been completely unable to find any ...
0
votes
1answer
63 views

When to use a digital potentiometer vs PWM and mosfet?

When would you use a digital potentiometer over PWM and a mosfet/transistor? I don't understand the advantages/disadvantages between the two.
0
votes
2answers
52 views

Mosfet gate driving circuit

I saw couple of h-bridge circuits based on IR2184 driver that have following circuitry connecting driver and transistor: My circuit will be full h-bridge driver with load 20A 24V DC motor. I have ...
0
votes
1answer
68 views

How does a junction-less transistors work?

I have recently read in a book that in 2010,junction-less transistors were developed. I can't understand how a junction-less transistor can be used to amplify current or voltage with having any ...
0
votes
1answer
40 views

FET array - logical switch

This is the circuit I plan to implement to control a LED by a logic bit simulate this circuit – Schematic created using CircuitLab The datasheet of the transistor can be found here I ...
1
vote
1answer
50 views

How to drive luxeon Rebel LED

I was working on a project regarding building a high power LED driver as a excitation light to excite the florescence in the plant tissue. I want to turn the LED on and off at around 200Hz~10KHz.I ...
0
votes
0answers
53 views

Reset a chip on any change of signal

Here is some background info on what I am trying to accomplish: When a cable(12V signal) is inserted, the chip should be reset (pulled low) for only 1 second, then return to 3V3. But when the cable ...
2
votes
3answers
115 views

Why 60% overshoot with 55° phase margin?

UPDATE: Based on the answers I received, I got this working beautifully. There's a full outcome report in one of the answers below. I'm working through the design of an electronic load, basically a ...
0
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2answers
22 views

MAX1555 - High level logic output

I plan to use the MAX1555 chip The chip output a logic bit to indicate if current is pull from the charger ( POK pin- Chip 1551 , CHG pin - chip 1555) The datasheet talk about the low state, being ...
1
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2answers
37 views

MOSFET/IGBT Current capacities and SOAs

I need to switch off a 20V 60A DC current electronically. I don't want to use a relay, due to the environment (vibrations etc.). It is not a switching supply, just a switch that turns everything off ...
1
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2answers
95 views

MOSFET oscillation with gate resistance

I'm trying to make a current buffer for high currents, using an LM324 and BUZ70. This is the circuit: simulate this circuit – Schematic created using CircuitLab I've noticed that this ...
0
votes
1answer
38 views

Undestanding the SOA of MOSFET from the datasheet?

I was checking my MOSFET for the selected power class. Could somebody explain the decoding of SOA of the MOSFET from the datasheet specs. I want to know which regions are considered during the ...
1
vote
1answer
46 views

Does this Schottky provide MOSFET transient protection?

I'm studying the schematic for an electronic load available as a kit from Jameco: http://www.jameco.com/Jameco/Products/ProdDS/2161107%20Schematic.pdf There is a Schottky diode shunting the ...
4
votes
1answer
58 views

Pull up resistor in NMOS logic value

For my senior high school project I decided to build a basic CPU from discrete components. I plan on using a 5V logic level and the current design calls for around 2000-3000 N-channel MOSFET ...