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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1answer
405 views

Mazzilli flyback driver mosfets keep failing

I've been trying to build a high voltage generator consisting of a high-voltage transformer and a Cockroft-Walton multiplier. I have actually tried several different drivers to drive a high-voltage ...
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2answers
122 views

Low power tube headphone amplifier design

I have never worked or even listened to tubes/valves before, so its about time I did. I wanted a simple design to work with being my first tube project, and have found this from diyaudioprojects.com: ...
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3k views

Dual active bridge converter

I'm having issues calculating the power losses associated with the operation of a bidirectional isolated Dual Active Bridge DC/DC converter. The converter is controlled using Phase Shift Modulation (...
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0answers
94 views

How to suppress noise in my circuit

I illustrated what my circuit do as you see. Switching frequency is 800 Hz. When I increase the load, a noise is heard from my circuit. Here is my drain oscillocope view in frequency domain. What can ...
3
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2answers
290 views

Is there any advantage to using multiple tracks in this PCB design?

I'm fairly new to PCB designing, but I'm loving experimenting with it. Currently, I'm trying to develop a simple PWM circuit using MOSFETs to control an RGBW strip, using an Arduino with an integrated ...
3
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2answers
59 views

MOSFET pinchoff reduce current

I understand that in an n channel MOSFET as Vgs increases, electrons are attracted towards the gate forming an n channel. These electrons are responsible for the conduction of the MOSFET. As Vds ...
3
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1answer
203 views

How do actively driven mosfets or transistors react to floating source?

Attempting to add some lights to a car's "intelligent" lighting system. Want to make sure I understand how my n-channel mosfets will react to losing their ground, while their gates are still connected....
3
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0answers
225 views

Gate of a transistor and mosfet damaged

In my schematic, I found that the base of transistor Q7 (2n2222) was damaged. I tried to replace it with a BS170 MOSFET, and the same thing happened where the gate was damaged. The microcontroller ...
3
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1answer
319 views

Parasitic Capacitor current of an inductor

I am doing a double pulse test on SiC MOSFETs from 100-800 V and current from 20-80 A. The schematic is shown in figure (the values are not correct though). In my first round of tests (Figure 2), I ...
3
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3answers
1k views

Audio soft mute using optically isolated MOSFET

I have an audio signal running through a device that switches it over using a mechanical relay, as a result of the DC offsets and the parasitic capacitance on the output (which also connects to a high ...
3
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1answer
281 views

Why does the signal MOSFET keep failing in this circuit?

The following is the power control part of the circuit I use in my car to control the wing mirror folding motors, the idea is that the whole circuit can power itself off after its done its job to ...
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0answers
28 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 ...
2
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2answers
110 views

MOSFET-based ring oscillator not oscillating (but oscillate in simulator)

I created the following ring oscillator: In the LTspice simulator, it is supposed to oscillate at ~3Hz (LTspice source) given the 47nF caps and 680kΩ resistors: I then built this design on a PCB ...
2
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0answers
96 views

Designing MOSFET bridge rectifiers for high voltages

I've been looking into MOSFET bridge rectifiers, also known as "zero IQ" rectifiers, as a replacement for traditional diode-based bridge rectifiers. Here's a simple example: The benefit, of course, ...
2
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2answers
318 views

Connecting battery packs in parallel and series, each with their own BMS

Recently I bought cheap a lot of CASIO DT-9723LI battery packs. Every pack consists of 2 Sony 6th-gen Li-ion 18650 cells and its own 2s BMS. Here the question arises: Can I connect this packs ...
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0answers
64 views

Pulse Transformer design problem: cant understand for sure whats the reason or irregular output waveform?

A ferrite core pulse transformer provided with 12V PWM signal (as primary winding input voltage) as shown in Fig-1, produces irregular output voltage across the secondary winding as shown in Fig-2. I ...
2
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0answers
37 views

MOSFET as a Switch with 26 V Circuit

I'm pretty green with electronics and I've encountered a situation I need some help on. Any help would be greatly appreciated. I've created a circuit wherein I am inserting a logic-level MOSFET (...
2
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0answers
47 views

Automatic power switching between two DC sources with a switch to charging in the second position

I am designing a circuit which will automatically switch to be powered by a single 18650 when the other voltage source is disconnected. It will use a DPDT switch, the second position of which will ...
2
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0answers
68 views

Buffer-cum-Level shifter using dual MOSFET

I am putting together a Buffer-cum-Level shifter using dual MOSFET to deal with PWM signal for display backlight control. This 3.3V PWM signal is driven by MSP430G2452 and would be reaching the ...
2
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1answer
81 views

When to use P-Type current source(using pMOS) and when to use N-type current Source(nMOS)?

I am referring to Prof. Behzad Razavi Lecture https://www.youtube.com/watch?v=GAvZLyii3aw&list=PLiDoPUX9nLkIw9EnIv_3K19wlcyJ6msYd&index=2 (Minutes 19-26) Prof. says to use nMOS when we draw ...
2
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0answers
103 views

Switching speed of MOSFET and BJT

I've read on the internet that MOSFET is faster switching device than bipolar transistor, however, i don't understand why. Considering the fact that transconductance of bjt is grater than ...
2
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0answers
121 views

Humming and voltage drop on p channel Mosfet

I am designing a high side switch using P-Mosfet to drive a heat element. The Mosfet is driven by PWM from MCU, which in the test is around 40Hz, 10% duty. Here is the schematic I am testing. I am ...
2
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1answer
43 views

Mosfet channel length modulation

Consider the nMOS for simplicity, even in saturation, Ids grows with Vds because the depletion region around the drain grows too ...
2
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0answers
65 views

Calculate the junction temperature of a MOSFET during pulse

Hi all I have a question regarding using a MOSFET for a constant current source. I have found this question with some answers but it wasn't clear to me yet. I want to create a constant current LED ...
2
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0answers
320 views

Large negative current spike in N-Channel MOSFET source when turn-off

I am working on repairing a power supply board of a LCD TV (200W power), more specifically, the PFC section (active power factor correction). See schematic (adapted from here): I've replaced some ...
2
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2answers
43 views

R_on for inverter gate

What \$R_{on}\$ do I use to calculate the delay for an inverter gate? In my class we came up with two definitions of \$R_{on}\$, one for saturation and one for triode. Is there a certain mode I ...
2
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0answers
54 views

Can I generate following voltage waveform with single PWM FET?

I am designing power supply which must output following voltages at a maximum of 1.5 A stepped down from a 24 V DC supply. 24 V 13-15 V 0-5 V Waveform for one of the inputs requires following ...
2
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0answers
77 views

Controlling IRL2703 with 3.3V (Reading MOSFET datasheets)

I have an application where I want to switch on/off a resistive load (24V/300mA) from a 3.3V MCU GPIO pin at a rate of 1 HZ or slower. I also have some IRL2703 MOSFETs, and I wonder if they would do ...
2
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1answer
445 views

Is it okay to connect 2 lithium ion battery in parallel to a charger that can maintenance 4.2V? (more detail in post)

So I'm planning to make a charger that can charge multiple lithium batteries in parallel with hope to use recycled one. I fully understand that they are dangerous when you do it incorrectly, so I just ...
2
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0answers
71 views

Questions about a remote relay control application with a MOSFET

I need to control eight solenoid-valves for water drainage outdoors, remotely and simultaneously. The valves are normally closed (NC) type which I guess, in that context, means they open and let the ...
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0answers
369 views

High Voltage Cascode with MOSFET LT Spice Simulation

I'm an electronics engineering student and want to develop a high voltage switch with normal Si N-MOSFETs. After some research, I discovered cascode switches for this application. Most of these ...
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0answers
166 views

Inverter Design - High Side MOSFET - Slow Switch Time

I've posted previously on a similar issue which can be found here Overview: My design is a 3 phase inverter with: MOSFETS are STF10N60DM2 Gate Driver is 6EDL04N06PT I'm using only a single high ...
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0answers
228 views

How does a cascode current mirror maintain equal Vds of the bottom transistors?

A basic current mirror is shown below: The load and reference current relationship is affected by channel length modulation: In order to cancel the effects of channel length modulation, vds1 and ...
2
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0answers
62 views

How does a MOSFET conduct in saturation region?

It is a simple question but I could not find a straightforward answer. When a MOSFET enters saturation region, the channel length starts to decrease, and the channel width is the smallest near the ...
2
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1answer
402 views

How to make battery controller with arduino?

I want to make simple UPS with means of arduino, to learn the processes from it, and be able to record and monitor at PC. For the start i want to implement buffered usage charge mode. Logic is simple -...
2
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1answer
329 views

Programmable Electronic Load Design

I am trying to design a programmable electronic load for testing the PWM outputs of PLC controllers. The outputs operate between 5-36 V and 10-2000 Hz frequency. The output is supposed to tested for ...
2
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0answers
144 views

Measuring battery voltage, capacitor on drain (nMOSFET switching load)

I've got a schematic to measure a battery voltage using a nMosfet (triggered by a GPIO high level). The voltage is measured at the Probe (see picture). Can you tell me the purpose of Capacitor C1 on ...
2
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0answers
368 views

Adding a ferrite bead to source of mosfet (smps)

We are designing a SMPS (ultra low noise) based on TI schematics http://www.ti.com/lit/df/tidrgc2/tidrgc2.pdf (5V, 15W quasi resonant) In order to reduce EMI (we have some ringing across Mosfet when ...
2
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0answers
212 views

Load Sharing/Isolation Circuit with ADP5063

I'm designing the battery power/charging circuit for the Reform DIY laptop which uses a (big) LiFePo4 cell. For the charger IC I've now settled on ADP5063 as it seems simple and can charge with 1.5A ...
2
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1answer
595 views

MOSFET Sizing in Wide-Swing Current Mirror Design Exercise

TL:DR How do I know how to size transistors? This is the same problem as this one. Now knowing that I can change L, I know that my W/L ratio to make Von = 200 mV is roughly 6.75. Also knowing that ...
2
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0answers
193 views

What MOSFET circuit replaces a diode in a 48V 40A escooter?

I want to use a 1kW generator and convert my eScooter to a hybrid. The scooter uses a 48V SLA battery bank of 4x22Ah SLA batteries in series. I used a transformer from a 1200W microwave oven and ...
2
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1answer
307 views

Proof of type for Current mirror and Early effect (Mosfet transistors)

Can anyone explain me how I can prove this equation below (4.19).I know that \$V_{GS1}=V_{GS2}\$ and assuming that M1,M2 is in saturation then \$ID=0.5kn(vov)^2(1+\frac{V_{DS}}{V_{A}})\$
2
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1answer
727 views

High side RC ESC switch

I've been designing a test bench for RC propulsion systems and for that I thought it would be nice to be able to switch the power to the ESC on/off. For this I designed a simple circuit which I ...
2
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2answers
286 views

P-MOSFET Dropper-Switch - Linear Region

I'm repairing an ECU board from a SCANIA generator. It works with 24Vdc, and on the last maintenance the technician powered it with 220Vac, so it blew up some components. I've managed to replace the ...
2
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1answer
163 views

Noise in FET reverse-polarity protection for ADC

I have quite precise ADC circuit. I want to protect input supply voltage (not ADC input) from reverse-polarity using FET transistor as shown on the picture below. I wonder: is there any noise / worse ...
2
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0answers
422 views

Conduction angle in three-phase rectifier

In a standard three-phase bridge rectifier, which consists of 6 diodes, each diode (or thyristor) conducts 120º of the full 360º period. I have built a synchronous rectifier (for research purposes), ...
2
votes
1answer
209 views

Smart mosfets, logic level input(mosfet replacement)

Basically diesel heater ecu my car uses has an shorted "smart" mosfet BTS141, which drives the glow plug. I don't know much about it since i cant determine the manufacturer. Basically it accepts logic ...
2
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0answers
104 views

Input selection circuitry for USB/battery

I'm making a development board, and trying to sort out the input selection circuitry, where if a battery (3.7V lipo) and USB is connected at the same time, it doesn't damage the circuitry, by stopping ...
2
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0answers
178 views

Protection High side Mosfet driver with less solenoid connection

I suggest control solenoid. Solenoid will be connected externally via a connector. Steering is via high side MOSFET driver. The requirements are for detecting disconnection, short circuit and current ...
2
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1answer
5k views

Straight forward method of adding encrypted third party models to LTSpice's Model Tree

I have >20 different types of MOSFET from fairchild that I would like to add to LTSpice's model tree. Fairchild encrypts their libraries. What is a straight forward method of adding their libraries to ...

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