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)

learn more… | top users | synonyms

0
votes
1answer
16 views

Arduino PWM control MOSFET

I have a bit of a problem that in hoping someone can shed some light on. I have a 4 wire fan (from a power mac g5) and I found that the pinout is positive, negative, PWM and rpm output. It's a bit ...
0
votes
0answers
10 views

If you put a MOSFET in backwards does the impedance change?

if I stick a MOSFET that should be going (S-D) to positive in backwards, and make it (D-S) to positive, all the current drops across the diode instead. This diode then approaches an impedance of 0. ...
0
votes
0answers
11 views

What is Co(er) for a MOSFET?

http://www.aosmd.com/res/data_sheets/AOK42S60.pdf Page 2, dynamic characteristics. Why is that different to the Coss I get on, say, figure 9 at 130V? Should I add it to Coss to get an accurate ...
0
votes
1answer
22 views

multiple mosfets controlling individual circuits sharing one pull up res?

i'd like to control several individual circuits using an array of MOSFETs and wondered if they have to have individual pull-up resistors or if they can share one connecting them to ground. Or do the ...
1
vote
0answers
39 views

Calculating signal attenuation for AC?

So we've got this; simulate this circuit – Schematic created using CircuitLab Which I've been told is equivalent to the sum of it's Coutputs to an AC signal; simulate this circuit ...
0
votes
1answer
15 views

Mosfet driver ir2301s

I try to implement brushless motor driver using IR2301s driver. I start with testing the driver without MOSFET's. Here is scheme: In datasheet for IR2301s given this picture: If I understood ...
0
votes
1answer
37 views

What should be the source impedance and load impedance in LC filter design?

My aim is to generate analog signals with class-D amplifier. For that I am using the following configuration: Class-D-->Low-pass filter(LC)-->load(complex, real+imaginary) class-D amplifies my PWM ...
1
vote
1answer
39 views

Procedure for finding the right MOSFET, diode and resistor to make a solenoid valve open/close?

I need a right MOSFET to make a 8 valves open/close about 15 times per second! It needs to switch very fast. Anything that can slows the speed of the valves is not desirable. From what I see the ...
0
votes
0answers
47 views

Changing the resonant frequency on the fly?

So I have a coil and a default capacitor, they resonate at 150kHz. I have these three SSRs in place, they "add" a capacitor into the circuit. Here's a simplification of one switch; simulate ...
2
votes
1answer
71 views

Very odd open-drain output design

I ran across a open-drain design and am baffled by the resistor between the nFET source and ground. There are only two purposes that I see it could serve. 1) It's series source termination, matching ...
1
vote
1answer
110 views

MOSFET transistor

Circuit a) presents the circuit of polarization of a MOSFET and b) the equivalent model of small signal on \$g_m\$ is the transconductancy of the dispositive, and \$r_0\$ an equivalent resistance ...
0
votes
2answers
83 views

Why would MOSFET transistor heat up?

I had a circuit on PCB. I used solder with acid-core to solder it. This combined with my mess soldering caused various shorts between components. One of those components was MOSFET transistor BUZ11 ...
0
votes
4answers
75 views

Switch from 3.3V to 24V Raspberry Pi

I want to convert the Raspberry Pi's 3.3V output to 24V as this is what the I/O uses on the Universal Robot arm, UR5. The 24V is supplied by the UR5 and so I thought that a simple NPN transistor would ...
0
votes
2answers
48 views

voltage drop over IRF9540 = IRFZ440N H-Bridge

I am trying to build a simple H bridge as part of a learning curve. At the moment it is on a breadboard. I am using 2 P-Channel MosFets (IRF9540) and 2 N-Channel MosFets (IRFZ440N). They are tied to ...
0
votes
1answer
101 views

Why PNP transistor might be opened even though (almost) nothing is connected to the base?

I have a simple printed circuit board with simple circuit on it. Very beginner. No SMD. As a part of this circuit I have transistor BC557. If I don't solder the base pin of this transistor and test ...
0
votes
0answers
57 views

Please help me with my capacitance-adding circuit

It's to add capacitance to a little tesla coil, (Bigger schematic, right click > open in new tab to view full size) Please note, I removed the capacitor and resistor on the gates. For some reason ...
3
votes
1answer
78 views

555 fading in&out if possible with pwm & led array

i'm new here and also in the electronics world so pls be patient with my ignorance. I's now months that i'm fascinated by the 555 timer. The stuff you can do with such a tiny thing is impressing. ...
1
vote
1answer
54 views

High current Synchronous Buck Converter, MOSFET or IGBT?

I am supposed to design a synchronous buck converter (to be driven by micro controller control signals for switching purpose). The input Voltage range is 10V-15V, and output voltage range is 4V-5V but ...
1
vote
1answer
28 views

Rds(on) versus Vgs

I saw this graph in the datasheet of the Supertex (now apparently Microchip) TN0604: It shows a lower Rds(on) for a lower Vgs. Can that be right? Don't you require a higher Vgs to get a lower ...
0
votes
2answers
105 views

Power Mosfet - Unreliable High Speed Switching Behavior

Im having a peculiar problem with my circuit, your help is very appreciated :) My Set-Up I am using an FQP30N06L N-Channel MOSFET to pulse an array of LEDs at 38 kHz. A micro-controller (Arduino Uno ...
0
votes
1answer
45 views

What does 'W/DIO' mean when used for MOSFET descriptions?

For example on Farnell: VISHAY SILICONIX SIHP18N50C-E3 MOSFET,N CH,W DIO,500V,18A,TO220AB I've googled it in various forms but all it returns is other listings for MOSFETs with that in the title. I ...
0
votes
0answers
42 views

Driving the floating power MOSFETs

In a battery balancing system, I have four transistors and some of them are floating as you can see in this circuit: There are four battery packs each made of two batteries (Li-Ion) and charged via ...
1
vote
1answer
51 views

Dimming an LED Strip (9v) with a 555 timer and MOSFET

I'm doing some VERY amateur prop building for an upcoming night of cosplay and I'm trying to create a throbbing/pulsing crystal for the top of a magic staff. Initially, I was just going to use a ...
0
votes
0answers
47 views

Cause of shoot-through in H-bridge

I've designed an H-bridge for a 15A DC motor. Power is applied by plugging in a very high-capacity Lithium battery. Unfortunately, when I plug in the battery, one of the transistors goes pop instantly ...
0
votes
0answers
23 views

Computing K parameter for Mosfet/JFet/

I am writing a simple simulator for Mosfet and JFet. The equations governing these involve the important parameter "K". But, the data sheets normally do not provide the value of parameter K. So, I ...
1
vote
1answer
34 views

Precharging capacitors with P mosfet slew rate control - Unwanted turn ON

I am considering using a MOSFET to control the dV/dt rise (slew rate) when power is first applied to a DCDC power supply. This will hopefully resolve both a precharging issue I am having and the ...
2
votes
1answer
75 views

What is causing this level shift in my wave?

Excuse the quality, sorry; RED is GATE of Q2. YELLOW is GATE of Q4. 5V INPUT AT ALL STAGES What are possible reasons that my H-bridge has a little 'bump' at the turn-off of the high-side? It's ...
0
votes
3answers
87 views

Using a mixed technology, SMD and THT components in one PCB

I want change design from Through-hole technology to SMD design. Some components have no SMD version, for example some transistors in TO-92 package, and Power Mosfets, which available in DPAK SMD ...
0
votes
0answers
34 views

Common source configuration causing errors in KiCAD

I am trying to design a circuit with a N-type MOSFET that has a common source configuration in KiCAD. The standard PWR_FLAG on the Ground net makes it into an power output which generates errors with ...
0
votes
0answers
10 views

Why is the conduction band not continuous in flat band condition in moscap

He, I have a problem understanding the band daigram of moscap(MOS capacitor) under flat band condition. In the photo, it's quite clear that the band diagram is discontinuous at the substrate-oxide ...
1
vote
1answer
43 views

How to Find value of Early voltage of output characteristic curve of BJT?

I have this graph from data that I have. This is the output characteristic curve of BJT. I want to find the value of early voltage VA?
0
votes
0answers
28 views

Power MOSFET 27N3LH5 for SMT design

I want change existing through-hole type PCB design to SMT design. The existing design use Power MOSFET 27N3LH5 in TO-220(DIP) package and with Heat Sinks in output channels. The SMD version of ...
3
votes
2answers
87 views

Advantages of depletion mode FET devices over enhancement MOSFETs

I've grown the impression that JFETs and depletion mode MOSFETs are not used very much nowadays, especially in new designs. I know that they need different bias networks, especially as discrete ...
0
votes
0answers
27 views

MOSFET Voltage during turn off

I have a field stop IGBT and I just replaced the P+ collector at the bottom with n+ to change it to MOSFET to understand the difference by simulating the device in TCAD. I am simulating turn off ...
11
votes
4answers
550 views

Can a power MOSFET for switching application be used as a linear amplifier?

Power MOSFETs nowadays are ubiquitous and fairly cheap also at retail. In most datasheet I saw power MOSFETs are rated for switching, without mentioning any kind of linear applications. I'd like to ...
1
vote
2answers
50 views

Recommended Mosfets for switching purposes

I'm looking for common MOSFETs to do some experimenting with. They should be able to switch at least 3A at 15V, have a low on resistance for power efficiency and also be quite cheap. I require all ...
0
votes
0answers
25 views

Collector emitter capacitance of NPN transistor

I have a p-channel mosfet that I am driving it with a NPN transistor, similar to the diagram in this post, Using p-channel mosfet on high side of h-bridge, do I really need a driver chip?. When I turn ...
0
votes
1answer
45 views

Basic MOSFET question

I am using a P-Channel MOSFET to build a buck converter and change 12VDC, 2A (from a 12V battery) to 5VDC, 2A (for cell phone charging), should I use a MOSFET rated for 20V, 2A or -20V, -2A? I am new ...
2
votes
1answer
90 views

Using NPN BJT with a P Channel MOSFET to switch 3.3V to 24V

simulate this circuit – Schematic created using CircuitLab I have some 3.3V I/O on a PC Board. When an output is switched on, I need to switch the 3.3V output voltage with a +24VDC and ...
0
votes
0answers
60 views

How do you correctly measure the gate voltage of a MOSFET?

If you have a half-bridge, or an H-bridge, or some other usual configuration; and you want to see the voltage you are getting on the gate, to check for any errors and shoot-through. Do you do it like ...
1
vote
2answers
39 views

When are Avalanche-Rated MOSFETs Necessary?

Why do we care about avalanche rating for power MOSFETs in circuits that exhibit inductive kick (flyback converters, motor drives, etc.)? I understand the basic destructive mechanisms behind ...
1
vote
2answers
218 views

What is the ground-source voltage of this current mirror?

In Neamen's microelectronic book, there's a problem using this current mirror There is a 5V DC voltage source above the current source. The reference current is 250 microAmp. The threshold voltage ...
0
votes
2answers
26 views

Hi Drive MOSFET waveform for charge controller

I have designed a charge controller using the BQ24650 IC from Texas Instruments. Although I am outputting the correct voltage, the hi drive waveform is not the square-shaped waveform I was expecting. ...
0
votes
0answers
18 views

Noise with PWM Motor Driving Circuit

I'm using the circuit of this question: Problem with PWM motor driver The problem of the past question is solved using a 1200k resistor and lowering the frequency to 4 Khz: now I have noticed, using ...
0
votes
1answer
25 views

Problem with PWM motor driver

I'm using my custom circuit in the figure for driving dc motors. I'm providing a PWM (25khz). While trying the activation threshold (minimum duty cycle that activates my motor) experimentally I have ...
0
votes
1answer
24 views

Polarity of feedback in a feedback circuit

How should I check whether the given configuration has a negative or positive feedback. I am stuck because, I know that as Vin increases the drain current will increase but after that I don't know ...
0
votes
1answer
46 views

How to make Kicad alow P-MOSFET as switch without ERC problems?

I have a P-MOSFET which is acting as a switch. However, I get errors as seen in the image. How should I resolve this issue? I know i just could don't bother since i know it will work but I rather not. ...
0
votes
0answers
24 views

How does id versus Vds characteristic curve will change if Gate and Drain are shorted?

I was trying to solve this problem 5.19 From Sedra & Smith for microelectronic circuits 6th edition For the below circuit, Find an expression for Vds in term of id, Sketch the graph for Vds ...
1
vote
1answer
84 views

Can I alter this circuit?

I am making the following solar charge controller circuit based off of the NE555: This is the webpage I got the schematic from: http://mdpub.com/555Controller/ The potentiometers at the trigger ...
0
votes
0answers
26 views

What topologies are used for synchronization of AC power in a micro inverter?

I would like to know the design pattern utilized in syncing the AC Sine output of a micro-inverter (or inverter in general) with the grid. Please also give any good resources for designing an ...