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
30 views

FET and BJT transistor question

We have the circuit in the figure BJT transistor has the parameters β=80 and the JFET transistor has the parameters Vp=-4 Volt and Idss=8 mA; Vgs=-2.6 Volt and Ids=1 mA We have R1=470 Kohm ,Rc=3.6 ...
1
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0answers
14 views

Bootstrapping a bidirectional MOSFET switch?

is it necessary to use a driver and bootstrap circuit in order to make this configuration work; Or can I just stick 10V in it like shown? This is to make a bidirectional switch, I'm not pulsing ...
1
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2answers
43 views

Differences between current sources transistor and current mirror

In this configuration simulate this circuit – Schematic created using CircuitLab if the two pMOS are equal, they provide the same drain current to both the branches: suppose that Vbias ...
0
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0answers
32 views

How to switch on or off capacitance on a piece of conducting material?

I don't know if this is the right way of describing it, but I need to activate an area of capacitance on a touchscreen by applying some current to a piece of conducting material like tinfoil. I am ...
1
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1answer
30 views

Discharge of a load capacitor through a cascode

How will a cascode effect the discharge of the load capacitor? I would expect that the discharge trough the cascade is slower since the cascode has higher output impedance. simulate this ...
3
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2answers
88 views

How to switch a Bluetooth module with a P-Channel MOSFET high-side switch?

I am looking for a high side switch to turn a Bluetooth module off when not in use. The module uses 100mA at most and runs on 3.3V. I am using a ATMega328 to talk to the module and it runs at 5V. ...
0
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2answers
69 views

Explain in layman's terms Vgs and Vgs(th) of MOSFET's

I'm trying to understand Vgs of MOSFET transistor; from what I understand Vgs normally stands for voltage gate to source breakdown, but other than that I lack an understanding. Vgs(th) is the ...
0
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0answers
17 views

Use Mosfet to switch secondary Powersupply on

I'm building a small computer that uses a Thin M-ITX motherboard. But I'm also using an GPU that is being powered by a secondary board. This secondary board has a regular 24-Pin ATX header. I know ...
0
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0answers
47 views

Reverse engineering MOSFET power circuit

I'm looking at a portable heater circuit that uses a 1.4 Ohm resistive load as the heating element. The circuit in question uses an N-channel dual output mosfet, and on the other side of the board a ...
0
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1answer
31 views

power mosfet switching basis

I have a really simple question. I have this simple circuit. This is a converter, where the power-pole is made as a power mosfet transistor plus a diode. I did not get the Turn-on behaviour as ...
0
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1answer
42 views

IRF540 power Mosfet 12 volt motor gate resistance

I have a IRF540 power Mosfet driving a 12 volt motor. Currently I am using a 100 ohm gate input resistor, It is working fine. What I want is the maximum gate resistor value that I can use and still ...
0
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3answers
106 views

MOSFET not fully OFF when Gate Voltage is 0V

A N-channel MOSFET STP16NF06L is used to drive a 12V load. Pin 1 is connected to Arduino Uno digital pin 4. Pin 2 is connected to the negative terminal of the 12V load. Pin 3 is connected to the ...
2
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2answers
100 views

Polarity of feedback for a mosfet circuit

I came across this question in "fundamentals of microelectronics" The objective is to find out the polarity of the feedback. Could someone help me with this? My approach to this question is as ...
3
votes
1answer
124 views

MOSFET and Driver. Gate current questions

I am designing a three phase bridge inverter and I have some questions about the MOSFET driver. My MOSFET has a total gate charge (Qg) of 200 nC and a internal gate resistance of 2 ohm. I want it to ...
1
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1answer
58 views

H Bridge with PWM input giving small voltage outputs [duplicate]

I designed a H bridge to work with pwm input and to select between directions using a mux; However, when I run simulation, I get an output like this on the oscilloscope; I am using FQP7P06 for the ...
1
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1answer
30 views

LTspice MOSFET width sweep

I am trying to simulate the transfer characteristics of a CMOS inverter using LTspice. I want to sweep the MOSFET width and length and observe the effects on rise and fall times of the CMOS inverter. ...
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votes
1answer
35 views

irf840 power mosfet [on hold]

can irf840 power mosfet pass ac and also is it possible to logically control it? I have the need to control an ac motor with a microcontroller (msp430). so whenever there is a dc signal from the ...
1
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0answers
18 views

PWM capable H-bridge, best low side drivers

Im trying to make a high current h bridge 24volts around 60amps to start off with however I might decide to up it 120amps continuous if I can easily. I have already made a simple high side mosfet ...
0
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0answers
37 views

Low cost solutions for reversing 130VDC 20A motor

I have a treadmill motor controlled by an MC-60 controller board. The motor is reversible and I want to control the direction using an Arduino. The catch is that it's 130VDC and 17A (the voltage ...
0
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0answers
27 views

Isolator for MOSFET switching

I am operating power MOSFET at 100khz. Signal for gate is given by MCU which is then given to MOSFET driver and then fed to gate. I want to build MOSFET driver can anyone help me in specifying the ...
1
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2answers
46 views

Use of MOSFETs body diode

I have an N-MOSFET array IC and I don't need to use all of them, but I do need to use a diode. Is it OK to use the body diode of one of the MOSFETs as a regular diode to decrease component count and ...
1
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0answers
59 views

Understanding power dissapation of MOSFET's

I'm currently trying to understand how MOSFET's work in total but come across confusing information when looking into power dissipation of the mosfet; mainly how to calculate it. Say I have a circuit ...
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0answers
58 views

Coilgun troubles

I am trying to make a coil gun and I'm following a design made by Mehdi Sadaghdar the link is below. http://www.electroboom.com/?p=101 I am having trouble with my IRF540N nmos transistor. At first I ...
1
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1answer
46 views

Which MOSFET is best for me? [closed]

I plan on driving a heating coil of about 1.4 Ohms from a 3-4V power source; which gives an current draw of 2.14-2.85 A. So Watts from the following info is 6.42-11.4 W of power. The MCU will output a ...
0
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3answers
129 views

Power optimization for high-side switch

I'm trying to figure out a way to optimize the power consumption of a group of two high-side switches. They are not supposed to be switched more than once every minute. I don't know if my way to ...
3
votes
3answers
261 views

Control Power Resistor with MOSFET

I am making a temperature control system using an Arduino. However, I have a problem with controlling a power resistor (which is used as a heater). I was suggested to use a MOSFET to control it. ...
0
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1answer
41 views

NMOS Channel Type

I've seen some conflicting information about the inversion channel for an NMOS device. Is NMOS n-channel or p-channel? And is the substrate n or p? I know PMOS is just the opposite for both and the ...
1
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3answers
38 views

using a NOR gate output to a mosfet switch, improper high level output voltage

I am using a hex 2input NOR gate IC (TI SN74AS805BN). NOR Datasheet with a 5V regulated supply I want this to control a power mosfet switch Vishay FB180SA10B MOSFET Datasheet. The problem is that the ...
0
votes
2answers
27 views

Best way to control heater coil in portable application

I have a resistance wire (kanthal) that is about 2 ohms; with a power source of 3.5V. I'm trying to figure out the most efficient and portable way to control the coil; I'm toying with a mosfet right ...
0
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0answers
55 views

Why does load position affect dissipation of MOSFET [duplicate]

I am trying to use two MOSFETS to pass AC through a load but i noticed uneven temperatures between the two switching devices. In the configuration Below the lower FET heats up more than the upper ...
1
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2answers
88 views

Driving high side MOSFET problem

I designed a simple half bridge circuit using popular FET driver IR2101 (switching freq. around 500 Hz, drain current about 250 mA, supply voltage about 12 V): Of course I have resistive load ...
2
votes
2answers
131 views

MOSFET as Variable Resistor in High Amp Circuit

I'm trying to create a variable wattage heater circuit as shown below. I'm clearly not a trained electrical engineer (simply a hobbyist) so please forgive my crazy idea and general stupidity. You ...
1
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0answers
106 views

One MOSFET appears to get hotter than the other

I am trying to figure out some sources of error in this circuit. Firstly, the lower FET (in the schematic) seems to dissipate more power and heat up faster than the top FET. The shcematic above ...
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2answers
58 views

Complex circuit analysis

I need help solving the circuit above. I don't understand how to analyse the op amp using the small signal model in order to calculate the Vout/V3, the input resistance (Rin) and output resistance ...
0
votes
1answer
71 views

Driving a 3v Latching Relay with an 1.8v logic MCU Not Working

I have a battery powered device with an 8051-base MCU running off a 3v coin cell (with a DC/DC converter down to ~2.1v). I'm attempting to drive a 3v dual-coil latching relay using two GPIO pins of ...
0
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0answers
36 views

ckt flicker removed with hand touching drain

I have a boost circuit to control LED light. The circuit PI is controlled by microcontroller through software. This circuit works fine till some current at load but as I increase current after some ...
8
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2answers
434 views

Choosing and biasing a MOSFET controlled by a microcontroller, does current matter?

I need some help choosing a MOSFET for the circuit that I described here, which I originally designed using a BJT but decided that FETs make more sense in this case. The FET will be controlled by a ...
0
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0answers
39 views

MOSFET gate Charge curve doubt

We are understanding Gate charge characterstics... In this, when Vgs reaches Vgs(th), Id starts increasing and Vds is still at VD. Once Vgs reaches Miller value then Vds starts reducing. But in ...
4
votes
2answers
475 views

Reduce noise from a Hall effect sensor

I am currently working on a magnetic levitation project using a Hall effect sensor for distance measurement. I drive the coil using two 12 V car batteries in series to form a 24 V DC source, ...
0
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2answers
58 views

Output Impedance of BJT/Mosfet amplifiers

I have heard in lectures that the desired output impedance for the BJT/Mosfet Amplifiers is LOW. But these transistors are Transconductance amplifiers 'by birth'. I mean they give output current ...
0
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0answers
72 views

Dual redundant 1.5V battery power system?

I'm trying to build an efficient way to connect two 1.5V alkaline batteries in a redundant configuration for my circuit. I only want one battery to be supplying power to the circuit at any given time. ...
0
votes
1answer
31 views

NEC 2SK3919 MOSFET replacement [closed]

A few MOSFETS have failed on my motherboard. And I was looking on the web to find a replacement for the ones that have died. The ones that are currently on my motherboard are NEC 2SK3919. The only ...
0
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2answers
29 views

Need help reading mosfet Safe Operating Area graph

Im trying to figure out the current limitations of a mosfet(SISA18ADN) I'm planning to use to check how much headroom I have. The datasheet states Continuous Drain Current that it can handle as ...
1
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2answers
100 views

Powering and controlling multiple 12V LED strips with Arduino LilyPad USB

I'm trying to use an Arduino Lilypad USB to control several separate 12V white LED strips. I am however struggling to work out how to power them. The LilyPad only operates at 3.3V and I thought a ...
0
votes
2answers
129 views

Why do I need I large resistor to the GATE of my MOSFET?

I tried to control the brightness of a LED using a Linear Hall Effect Sensor fed to an Arduino, and PWM output to the gate of a MOSFET connected to a 12V battery. The LED was flickering a lot, and ...
0
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2answers
47 views

IRF740 datasheet. Error in the datasheet or I'm interpreting it wrong?

According to the IRF740 data-sheet from IR or from Vishay (they are nearly the same, the Vishay is better to read), the Qg is specified as 63nC under Id = 10A Vds = 320V and Vgs = 10V. But at page 4, ...
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0answers
23 views

Charge sharing in MOS logic

I am currently studying for a test in Integrated Circuits and i am not sure if i solved the following problem correctly. The node Y is on an initial potential of 0V and CLK is V_DD, so that Y is ...
1
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3answers
117 views

How safely to send signal between logic and higher current pcb?

I'm designing a PCB with 4 FETs. These are driven in the same board by totem pole drivers, and their load are about 5A total. I am using PWM at 1000Hz. The signal comes from a logic IC in another ...
-1
votes
1answer
43 views

mosfet (n or p) as switch on vcc [duplicate]

In my case i am using the shematics in a truck, i have the ground everywere on the truck body. I would like to control a led strip using mosfet (N or P) as a pwm switch on VCC (transistor beetween ...
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2answers
49 views

Solenoid Driver Circuit

I want to drive a solenoid (12V load and 20A rating) using a MOSFET and an Arduino. What kind of switching circuit should I use?