Questions tagged [mosfet]

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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45 views

Mosfet (max 600mA drain) with RPi GPIO PWM output

Original posted drawing (probably now obsolete): Thanks to feedback (@transistor: thank you), I found how to create schematics right here. simulate this circuit – Schematic created using ...
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Microcontroller driver the gate of a mosfet with a pull up resistor to 12V

I designed a PCB to drive mosfets with a ESP32 micro-controller. The ESP32 will be connected to the PCB with wires from a separate PCB. When there is no micro-controller connected to the input of the ...
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28 views

High side mosfet- Extra pulse on turn off

I am making a 3 phase motor drive H-bridge using N channel mosfets (IRFB3607) and BJT based custom mosfet driver such that my turn on and turn off time is about 200ns. Right now I am testing the ...
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49 views

What type of capacitor do I need to stabilize USB voltage?

I am trying to use a "FET" (https://elinux.org/RPi_GPIO_Interface_Circuits#Using_a_FET) to switch the power supply to a USB speaker from my Raspberry Pi. It's working well, however when I turn the ...
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85 views

power mosfet with stm32

I started this circuit with stm32. But it doesn't work properly. When I set zero to all four pins and I don't want any movement, the voltage of 3 volts is at the two ends of the motor again. Or if I ...
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72 views

Charge 12 V, 1.3 Ah lead acid battery via 12 V, 5 watt solar panel

Can someone explain me the below circuit which is used to charge 12 V 1.3 Ah lead acid battery via 12 V, 5 watt solar panel? The circuit is shown below I need to know what is happening in this ...
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49 views

BJT Base-Emitter Voltage

I have a question about Bandgap Reference circuits. How did he get Vt*ln(n)?? This is how I did it:
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How can I choose a MOSFET based on Rds? I have understood all the parameters except this

I have understood all the parameters except Rds and conduction loss. Please explain them to me. I am using a lithium-ion battery pack of 36 V and its maximum voltage is 42 V to drive a motor. Motor ...
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MOSFET Gate driver - negative voltage with Zener circuit

I was reading about minimizing MOSFET switching loss when I came across an article by Texas Instrument on how to use negative voltage, instead of ground, to faster discharge MOSFET gate capacitance. ...
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73 views

Why PMOS act like “close switch” when zero voltage

in PMOS that Vtp less than 0 , from what I understand if We give Vg less than Vtp it has current flow from source to drain ,on the other hand if we give Vg more than Vtp it cut-off. but in digital ...
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Two 24V switching power supply in one fused switch?

I have two Meanwell 500w 24v 21A PSU that are going to control different heaters on a 3d printer but I don't know how to connect them in a single IEC C14 fused plug switch. They need to operate ...
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46 views

How to build synchronous boost converter with IR2104 mosfet driver?

Does anyone know how to build a synchronous boost converter with IR2104 mosfet driver? I am a beginner and I have noooo ideaaa how to connect the circuit. The placement of inductor and capacitor ...
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324 views

P channel MOSFET switching problem

I was trying to build a 16x9 LED matrix with an MCU with a limited amount of pins. The Anodes of the LEDs are driven by P-channel MOSFETs which gates are driven by a 74HC595 8 bit shift register. the ...
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56 views

I'd like to know if this MOSFET switches design is okay

I have a design where the power of my circuit comes from a 12V battery and I use the energy from the battery to turn on/off a solenoid valve using an ESP32 (which outputs 3.3V from it's GPIO). In ...
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1answer
37 views

Reverse Phase Dimmer MOSFETs

I have a comprehension question regarding the design of a reverse phase dimmer. I have a picture attached of the part of the circuit I do not understand: The line is connected to the Drain of Q2 and ...
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Calculate MOSFET Forward Voltage Drop

I'd like to better understand how to calculate the voltage drop between the Drain and the Source of a FET. As an example, say we have a MDD1902 N-channel FET. How would I determine the maximum ...
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1answer
34 views

Logical Effort Inverter Sizing

I'm currently trying to size some logic inverters (CMOS IC Inverters, not power converison) based on the Logical Effort Approach. This approach requires that you know the input capacitance of an x1 ...
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32 views

Using a single MOSFET as an RF switch

I'm assembling a receiver kit from QRP labs. It is an inexpensive kit designed to cover HF. This kit has a BS170 at the input which I assume is intended to disconnect the receiver when the transmitter ...
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45 views

Solid state switch with Terra-Ohm off-impedance

I am looking for a way to create an ultra-high impedance switch without mechanical components. The off-resistance should be around one Terra ohm for a signal range of 10V DC max. On the other hand, ...
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1answer
88 views

AC MOSFET Switch

I'm trying to use MOSFETs to allow or block 450kHz sine wave. Here's the test circuit: At low frequency, MOSFETS are totally able to switch on and off. But when the frequency becomes higher at 450kHz,...
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80 views

Can 12V relay be used instead of 5V relays?

I have the project of making a touch switch using the IRFZ44N MOSFET for making a small led glow and stop glowing when I touch the probes. I thought of using a relay if I have to make a bulb glow, by ...
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91 views

Can a N-channel MOSFET used as a highside switch

Hello I would like to add a high side switch for my circuit. Typically a physical switch can do this job but due to form factor restraints the switches that are rated for my application does not meet ...
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83 views

Voltage divider with MOSFET for light detector with Raspberry Pi

Given the Pi’s 3.3V logic and risk of “frying it” with higher voltage applied at GPIO pin, I am using a voltage divider with MOSFET as a electronically-controlled switch to supply GPIO input. The ...
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63 views

Function Generator Voltage and Current handling

I am using this Function Generator My circuit : FG input : 5V peak to peak. 1kHz. 1ms time period. 90% duty. I want to understand the below questions : Is it safe to do this connection? I have ...
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Switch bounce protection due to impact situations

I use a small form factor switch along with a PMOS as a power switch to a circuit. Due to form factor restraint, the switch available (and was chosen) are susceptible to a bounce problem during ...
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2answers
54 views

Question about N-channel MOSFET turn on Voltage

I'm trying to understand a test result from a MOSFET-load switch circuit. The MOSFET tested after the load switch is DMN3404L, it's a N-channel MOSFET which has a typical Vgs around 1.5V. The load ...
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How do I pick a suitable SMD mosfet to control a 24V pneumatic valve with PIC32?

I need to control a valve (https://datasheet.octopart.com/VXZ242FGA-SMC-datasheet-110849414.pdf) of which I do not know its power consumption and drawn current. I don't have the part yet and usually ...
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75 views

MOSFET with very low Rds_on for very small current

I'm building a uCurrent Gold clone (https://www.digikey.ch/reference-designs/de/sensor-solutions/current-sensing/2637) - with a digital interface (measuring the voltage directly with a microcontroller)...
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27 views

MOS and BJT, why the difference

It takes longer for a BJT device to come out of saturation than a MOS device to come out of triode region. It is explained by the base charge storage time, the charge has to recombine and go back to ...
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54 views

Simplified Open Circuit detection

I'm designing a new PCB in which I'm powering a resistive wire via a MosFet, driven by a microcontroller kind of that way: Vdd: +5V several Amps (depending on the heating wire) Vin: 3.3V, an output ...
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2answers
57 views

What is this MOSFET for?

What is this MOSFET for? First I thought it's some sort of over-voltage protection but right after this, there's Zener diode doing the same?
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1answer
55 views

Capacitor between mosfet source and gnd?

This question has probably been answered before, but I am having a hard time finding explanations about the capacitors purpose. I have been looking at schematics of led matrix circuits and you can ...
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32 views

MOSFET current mirrors

so I am watching this lectures ( since the coranva virus , I am studying again electronics ). so at this lecture he is talking about MOSFET current mirros : https://www.youtube.com/watch?...
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What MOSFET parameters should I look into for this experiment?

I want to generate a low freq movement for this loud speaker coil by using a function generator sine output. With the function generator I can generate a sine wave between 0.2Hz up to 100Hz with ...
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Current Conveyor CCII internal circuital realization

I have read this article about current conveyor CCII, and I have some problems about understanding its circuital realization (page 4): The article says: The feedback of opamp structure [this ...
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1answer
29 views

What is the (exact) difference between CLM and DIBL in MOSFET?

I am wrapping my head around this for a bit and I understand both effects (Channel Length Modulation, Drain Induced Barrier Lowering). While CLM is usually explained as effective decrease of the ...
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26 views

What happens to the output voltage in CS Amplifier when signal source is large enough to drive the transistor into cutoff and triode regions?

simulate this circuit – Schematic created using CircuitLab Given this circuit of a common source amplifier with a resistive load, I know that as long as the signal source $$A\sin(\omega t)$$ is ...
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1answer
42 views

BTS441RG Chip Failure When Reverse Powered

I have this circuit that takes in two 24V power supplies and combines them via two BTS441 ProFETs. It then feeds either input A or B to a BTS6163 ProFET which provides protection and monitoring to a ...
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1answer
66 views

DC voltage at the output of push pull stage

I have an output stage. The circuit diagram is as shown: In DC condition, the node X has a DC voltage of Vdd/2. The node Z has a voltage of about 1.26 volts. Vdd = 3.3 volts. Transistors M7 and M5 ...
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49 views

Power switch using a lower rated switch

Hello I am in need of some advices, I am planning on placing a power switch for my circuit that uses 12v 2A DC. But unfortunately i could not find a switch with the form factor needed that is rated ...
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1answer
48 views

Drop-out voltage at the input using MOSFET

Please have a look at my below circuits. The first one is an MOSFET. N-MOS. Gate is fed with a function generator input of 5V peak to peak. 1kHz frequency. 1ms period. 90% duty cycle. Drain is ...
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2answers
85 views

Solenoid Getting Hot and Not Functioning Properly

Please forgive my ignorance on this schematic. I am new to using relays and solenoids so my diagram may be a bit inaccurate. I am attempting to control a DC solenoid with the GPIO pins from a ...
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5answers
208 views

Improving dV/dt turn-on immunity of a mosfet without increasing turn-off time

I'm designing a solid state battery disconnect switch and I want to improve the mosfets' turn-on immunity (high dV/dt on Vds) without impacting the turn-off time. I don't really care about the turn-on ...
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1answer
88 views

Why is this line connected to the microcontroller input in this schematic?

I found this wheelchair board and am trying to dissect some parts. I don't have many fancy tools so am just using continuity test to trace what goes where and this piece belongs to relay control ...
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1answer
78 views

What properties of MOSFET amplifiers made it so popular?

It seems to me that any circuit where the output voltage varies faster than the input voltage can be used to create an amplifier (for example a diode). We can bias the input voltage and use small ...
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1answer
59 views

Is it possible to make a jumper with MOSFET?

I have a PCB where two signals can be connected with a jumper. These two signals are neither GND nor VCC. The problem is that switching between the unconnected and connected mode requires a user ...
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Mosfet N and Vgs range

My schematic controls a Mosfet N gate by discharging capacitor voltage. It works, but when I calculated the min max, I've discovered that I'm a lucky man. Component : 2N7002 Vgs : Min =1 V / Typ : 2....
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109 views

Interfacing 24VDC output with 5V TTL input

I have a project which requires me to interface a 24VDC output module (PLC) with a rather outdated 5V TTL input module. From the schematics of the old module I can draw the conclusion that it uses +...
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4answers
194 views

Drop-out pulse test

I have a switching MOSFET circuit. Input to the switching MOSFET circuit is 11V at the drain. The gate is connected to a function generator. 5V peak-peak, frequency = 1kHz, 1ms (time period) & ...
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362 views

Best MOSFET to control small 12v load with NodeMCU? [closed]

I am pretty familiar with Arduino, and I will be using a NodeMCU for an upcoming project I'm doing. I have never used a NodeMCU before. I am using it along with a few sensors to turn on and off some ...

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